When I first learned about the Foundation’s information and diet twenty years ago, I was very skeptical. I had conventional university training as a nutritionist. I couldn’t imagine the Weston A. Price Foundation’s dietary philosophy as being right. However, I just kept reading and eventually realized—it is right. One thing I learned was that I needed a lot more vitamin A in my diet. I needed other things as well, but I think vitamin A was one of the big pieces I was missing. Why do we— myself and the Foundation—care so much about a single vitamin?
Vitamin A is necessary for almost every single function in the body. According to J. Timoneda, a researcher in the field of vitamin A, it is the most multifunctional vitamin in the human being.1 Commentators claim that deficiencies are rare in developed nations, but this is not true. Moreover, vitamin A is one of the most difficult nutrients to absorb and utilize. And Americans, or so-called “modern” people, don’t eat the best food sources anymore. Unfortunately, in my observations, most health care experts don’t think vitamin A deficiency is a problem and would prefer their patients not take any vitamin A nor consume any foods that are rich in it.
In his book Nutrition and Physical Degeneration, Dr. Weston A. Price emphasized the importance of vitamin A, noting that the diets of traditional healthy people he observed contained ten times more vitamin A than those of people he saw in the United States.2
VITAMIN A FOR EVERYTHING
Why do we say that vitamin A is needed for almost every function in the human body? We first think of it for vision and eye health. The true form of vitamin A is called retinol as its name corresponds to its importance for the retina of the eye. However, apart from vision, we need vitamin A for every surface of our body including our skin, eyes and gut.
Vitamin A keeps us from getting sick; it keeps our immune system from overreacting; it is necessary for growth and reproduction. We need vitamin A for building bones and teeth, and for the actions of our hormones. These are major roles, ones we’ve known about for a very long time, but there are others.
How does vitamin A do so much? It regulates the action of over five hundred genes in the body, which makes it a major regulator of all of our cells and how they function. Starting at conception vitamin A orchestrates the proper division and differentiation of every cell in the body. When cells differentiate properly, they are doing what they are supposed to do. You might say that vitamin A keeps our cells “behaving.”
How does vitamin A influence our genes? It works through something called nuclear hormone receptors—more precisely, retinoic acid receptors and retinoid X receptors. These receptors travel in the nucleus of the cell, binding and forming combinations with each other and with other compounds, like vitamin D and thyroid hormones. These receptors act to influence the action of our genes, which then influence which proteins are made, and ultimately, our whole metabolism.
By the way, every time we use a vitamin D molecule in the body, we use a vitamin A molecule also. That is why we must always think of these two nutrients together.
Without understanding anything about vitamins, traditional people always knew that special foods, ones that we now know are rich in vitamin A, were important to their health. Before the 5th century BC, vitamin A-containing foods such as liver were consumed and applied to the eyes and skin for healing purposes. Even Hippocrates documented this practice.
Scientists McCallum, David and Mendel discovered and named vitamin A in 1913. Dr. Price began his work less than two decades after this discovery, so he was acutely aware of the importance of vitamin A. However, not long after Dr. Price’s day, interest in vitamin A waned. Fortunately, there has been a resurgence of interest in vitamin A, with exciting discoveries in the fields of auto-immune disease, neurology, energy metabolism, cancer, stem cells and epigenetics.
According to Norwegian researchers Blomhoff and Drevon, authors of an important textbook on vitamin A, “After a period of rather low interest in the fat-soluble vitamins (we know as vitamin A, D, E, and K) we are now in the midst of a new wave of research on these vitamins with a large number of reports in influential national journals.. . . Suboptimal status has been linked to several diseases.”3
DEFICIENT OR SUBOPTIMAL?
Note that these vitamin A experts do not say that “deficiencies” are linked to several diseases. These authors say “suboptimal status.” So what does suboptimal mean?
We live in an industrialized nation where health authorities commonly believe that we don’t have a problem with vitamin A deficiency—that deficiencies are limited to the developing world. A few years ago, I testified to the FDA to protest the fact that they were taking vitamin A off the mandatory food labeling requirement and replacing it with vitamin D. The “experts” don’t think vitamin A is that important anymore. Even when vitamin A labeling was required, most of the vitamin A in the foods labeled probably wasn’t true vitamin A but precursors such as beta-carotene, from fruits and vegetables.
The current thinking is that vitamin D is more important than vitamin A. However, we definitely see vitamin A deficiency, even in the United States, and this has been an ongoing problem for a very long time. In developing countries where there is often not enough nutritious, high-quality food, true vitamin A deficiency is very common, leading to much blindness. Almost a half million children in the world go blind every year and half of them die within a year of becoming blind. The United Nations and the World Health Organization are actively working on this along with organizations, like the Bill & Melinda Gates Foundation.
In the U.S. we define vitamin A intake in terms of micrograms of “retinol activity equivalents.” (See Table 1.) Note that requirements for men are higher than those for women, although for lactation, it increases to 1,200 or 1,300 micrograms. The Recommended Dietary Allowances (RDA) is actually higher for small infants than children one to three years of age. Babies need more vitamin A as their cells are dividing and growing extremely rapidly. According to the National Academies of Sciences, Engineering, and Medicine, the organization that sets the RDA for all the vitamins, 95.7 percent of the population will meet its needs by taking this much per day.
It is critical to understand that the RDA was set to take care of the nutrient requirements we have for vision. But there are so many other things that vitamin A plays a part in, and experts in the field are right to ask, does the RDA cover everything that vitamin A is required for?
How are we doing in the United States? According to data from the National Health and Nutrition Survey for the years 2009-2012, between 35 and 65 percent of Americans have intakes “below the EAR.” The Estimated Average Requirement (EAR) is different than the RDA, as the EAR is set to meet the needs of half of the population. The EAR is much lower than the RDA—500 micrograms (1,665 IU) for a woman and 625 micrograms for a man (2080 IU). The assumption is that if everyone in the population consumed that much on a daily basis, half of the people would be okay and half would not be getting enough. But the EAR is a very low bar to meet. In fact, 65 percent of the population doesn’t meet the EAR from food alone. That is 65 percent of people who don’t consume enough vitamin A without non-fortified foods. If you add the fortified foods, we are down to 35 percent not getting the amount specified in the EAR.
So, a third of the U.S. population, eating the standard American diet (or whatever they eat) do not get the EAR of vitamin A—and remember that the EAR is a very low bar to meet. For some reason this isn’t considered a national problem. Has anybody heard of this as a problem? We’ve all heard about vitamin D as a problem, but have we heard anything about vitamin A? Now this doesn’t include intake from supplements, and that does make a difference. But if you’re looking just from all foods eaten, 35 percent of people don’t meet that very low EAR number. This is not limited to the U.S. Twenty percent of people in the developed world don’t meet two-thirds of the recommended intake of vitamin A. They also have lower-than-normal blood levels.
You may wonder how you would know whether you are getting enough vitamin A. The first question to ask is whether your diet contains any vitamin A-containing foods (See sidebar, page 16). If you eat liver once a week, you are probably fine. Historically, people would eat liver about once a week, as there is only so much liver in an animal. You wouldn’t be able to eat liver every day unless it was specifically set aside for you. You’d have to eat it less often than the other parts of the animal, although there are other animal parts that are good sources of vitamin A—such as the eyes. We tend not to eat the eyes in this country but you could put them into soup. The flesh behind the eyes of fish is rich in vitamin A, so fish head soup would be a good source.
Daily consumption of cod liver oil is very important. Its regular consumption started in the 1800s. You can meet your needs of vitamin A with a good-quality cod liver oil daily. A vitamin supplement that contains the retinol form of vitamin A with at least 3000 IU per day would also work for most people, depending on the diet, but if you consume liver or cod liver oil, you don’t need to supplement. Another strategy is to consume two to three servings of pastured dairy, two to four egg yolks, and several servings of red and orange vegetables (orange and red work better than green). That may meet your vitamin A needs but not as consistently as liver or cod liver oil.
We also need to remember that vitamin A is one of the most difficult nutrients to absorb and utilize. Both endogenous (inside the body) and exogenous (outside the body) factors affect how we absorb and utilize dietary sources of vitamin A.
An important question to ask is whether you are eating a lot of lean protein. Are you drinking a lot of protein shakes? Are you exceeding one gram per kilogram of lean protein without the fat-soluble vitamins in it? Too much protein will increase your need for vitamin A. Also, are you taking a supplemented amount of vitamin D on a consistent basis, more than 2000 IU per day? And do you consume a high amount of polyunsaturated vegetable oils? All these will increase your need for vitamin A.
Do you eat lots of high-fiber foods or take fiber supplements? These will bind vitamin A and take it out of your body. And what about vitamin A from fruits and vegetables? These contain beta-carotene, not vitamin A. Our bodies can convert some of the beta-carotene in our diet into vitamin A, but ironically large amounts of beta-carotene can create compounds that oppose the action of vitamin A at the cellular level. This is unlikely to happen with dietary beta-carotenes, but it is possible with supplements. In addition, some medications, like steroids, will increase your vitamin A needs.
BETA-CAROTENE VERSUS VITAMIN A
It is important to understand the difference between carotenoids and retinol. Retinol is the physiologically essential, or true vitamin A. It occurs only in animal foods, in the form of retinyl esters, which means the retinol molecule is joined to a fatty acid.
Colorful plant foods are full of a variety of carotenoids, many of which can be precursors to vitamin A. Beta-carotene is the most important of these; it must be enzymatically split down the middle to yield true vitamin A. It may seem like you would get two molecules of retinol from one molecule of beta-carotene, but you actually need twelve molecules of beta-carotene to get one molecule of retinol, due to limited absorption from diet and the inefficiency of this conversion. Carotenes split first to yield retinal and then are converted into either retinol or retinoic acid, depending on the needs of the body. (See Figure 1). Retinoic acid is the one that has the most effect at the cellular level through its action on our genes. Retinal is the form of vitamin A that functions in our vision.
It’s hard to believe that university classes in nutrition still teach us that we can get vitamin A by eating lots of carrots and colorful fruits and vegetables. I’ve had clients tell me they eat plenty of raw carrots so they are getting all the vitamin A they need. The truth is, you’d be really lucky to get a meaningful amount of vitamin A out of raw carrots; it is very hard for the intestines to extract it from the plant matrix, and on top of that you’d need to be a really good carotenoid converter. It’s even harder to get vitamin A from green vegetables. Dr. Alfred Sommer, one of the internationally renowned scholars on vitamin A, says in studies where people eat green leafy vegetables for a few months, vitamin A levels don’t even budge.4 So don’t depend on leafy greens, even if you think you are a good carotenoid converter.
Not only is converting carotenoids to vitamin A difficult, it is also difficult to extract the carotenoids from vegetables that are raw. It is easier to extract them from cooked vegetables, and easier to make the conversion if you put butter or cream or other traditional fats on your cooked vegetables. A good source of pro-vitamin A is unrefined palm oil—the orange palm oil—where the carotenoids are in the fat. Low-protein diets, lowfat diets, high-fiber diets and diets high in raw plant foods all make this conversion difficult.
Iron and zinc deficiency also inhibit the conversion of carotenoids to vitamin A. Iron is needed to convert beta-carotene into retinol, and zinc is needed for all aspects of vitamin A metabolism, including its transport around your body. If you have a lot of toxins in your body, especially toxic metals, conversion will be difficult.
Gut dysbiosis inhibits conversion. If you have had your gallbladder removed, conversion will be difficult because you don’t have much bile, and you need bile to convert carotenes to vitamin A. If you have hypothyroidism, if you are very old or very young, or you’re supplementing with another source of carotenoids such as lycopene, these can also block the conversion.
In my practice, I find that only a minority of my patients do well without including vitamin A as retinol in their diet. However, about one in every three or four of my patients has physical signs of vitamin A deficiency despite consuming colorful vegetables routinely. Because the conversion rate of carotenoids to vitamin A can be as low as 10 percent or less, this does not surprise me.
On the other hand, there are people who make this conversion very effectively, up to 90 percent in some cases; I suspect this is not common in my own patient population because the majority do better when their diet or supplement regimen includes a source of retinol.
Genetics definitely play a governing role in our ability to convert carotenoids. The list of all the genes that affect your vitamin A metabolism and how you carry it through your body is a long one. The inability to convert carotenoids seems to be more common among those of European descent.
DETERMINING VITAMIN A DEFICIENCY
Blood tests for serum or plasma retinol are not very helpful because the liver stores 70-90 percent of the body’s vitamin A and keeps blood levels tightly regulated between 45-65 μg/dL. This number does not indicate your overall vitamin A status—or how much vitamin A you have in reserve. Your blood level of retinol will not drop below 20 μg/dL unless you are severely depleted. Blood testing can indicate only whether liver stores are either depleted or filled to capacity.
To determine either deficiency or excess states, you should measure both serum retinol (or serum vitamin A) and serum retinyl esters (serum A palmitate); serum retinol should ideally be in the middle or upper half of the reference range and not less than 30 μg/L, and the serum retinyl esters should not be above 10 percent of the sum of the retinol and retinyl esters. Measuring fasting retinyl esters is done to check whether the capacity of the liver to store vitamin A has been exceeded, an uncommon but possible occurrence.
Figure 1. Chemical Structures
Obesity causes blood levels to rise even during a physiological tissue deficiency, while infection and inflammation can depress blood levels. Vitamin A levels in blood vary with “fed” status, that is, how recently you ate. If you are going to get tested, please get tested while fasting. However, I don’t recommend testing as I think it is unnecessary unless you suspect someone is deficient and you want to confirm that. Keep in mind you might be disappointed as blood levels can often be in the normal range despite someone having what appears to be a vitamin A deficiency.
There are better ways to determine deficiency than a blood test. Ask yourself (or your loved one) these questions: are you having a hard time seeing in the dark? Do you dislike or even avoid driving at night because you can’t see well? This is probably a sign of vitamin A deficiency.
More good questions: do you have little bumps on the back of your arms, on your legs or other places on your skin? Are your eyes dry or do you often use eye drops? Do you have frequent colds or infections? Do you have any sort of seasonal, environmental or food allergies? Do you have problems sleeping? Are you forgetful? Do you always need sunglasses when you’re outside in bright light? Do you have chronically dry skin?
Just because you have these symptoms doesn’t necessarily mean you have vitamin A deficiency, but you should suspect it. You can then confirm the deficiency by adding vitamin A-rich foods to your diet. It is always safe to consume a few servings of vitamin A-rich foods each week, including one or two servings of liver and see what happens.
All these signs of deficiency are linked with medical diagnoses. How many ads are there on TV for dry eyes? For allergies? For insomnia? There are now multiple creams targeted just for “bumpy” skin, or hyperkeratosis. These are medically treatable problems that may largely be the result of vitamin A deficiency.
Night blindness is considered the first clinical sign that somebody is potentially vitamin A-deficient. This is the way scientists measure the frequency of vitamin A deficiency in a population, by determining how many people are night blind. Night blindness is pretty common in developing nations. It is also something to watch out for in women of childbearing age. If it is severe enough, you could go completely blind. They say that doesn’t happen in this country, but who knows?
The reason people become night blind is because they don’t have enough vitamin A to recycle the visual pigment, called visual purple or rhodopsin, which allows you to see in the dark. When a very bright light shines in your eye, adjusting to low levels of light takes even longer. People have told me that it is hard to see for a few seconds when they are driving and a bright headlight gets in their eyes—it is scary! This is a classic sign of vitamin A deficiency and responds rapidly to vitamin A replacement. In fact, whether or not someone responds well to supplementation is a very good way to know whether someone is vitamin A deficient.
I saw a client recently whom I had not seen for several months. I asked how his night vision was. He said, “What do you mean?” At his initial visit, I had noted a few classic signs of vitamin A deficiency and I had given him a product containing vitamin A at a dose of 25,000 IU daily for a few weeks. “Oh yeah,” he said. He had forgotten about his night blindness. Improvement doesn’t happen overnight in every case, but it does happen, and then people often forget they had a problem.
Researchers in developing countries use a machine to test what they call dark adaptation: a bright light is flashed and then the subjects are timed to measure how long until they can see a second, dimmer light. A long wait indicates a vitamin A deficiency.
EYES, SKIN AND BONES
Why do we lose our night vision before our day vision? One theory holds that since losing your day vision would be much worse than losing your night vision, the cones for day vision get first dibs on vitamin A and the rods that function for night vision get it only if there is enough.
Unfortunately, there is an aspect of our day vision that gets affected with suboptimal vitamin A status without our noticing. If we don’t have enough vitamin A, then we can’t fully sense bright blue light, the natural daylight affecting our circadian rhythms. If we aren’t fully sensing that blue spectrum, our brain may not be fully aware it is daytime. This may affect our ability to sleep as our circadian rhythms are now disrupted. Interestingly, a few small studies have shown that in some individuals “color blindness” improved by taking larger amounts of vitamin A to correct what appeared to be a vitamin A deficiency.
Another thing that happens when you have vitamin A deficiency is that your eyes may become very dry. This happens when keratin-producing cells replace the mucus-producing cells in the eye. Bitot spots are the next progression and eventually irreversible blindness. Bitot spots are white, keratinized spots like little saucers on top of the eye.
Hippocrates mentions rescuing vision with liver applications. There are medical drops containing vitamin A that you can use for night vision problems and dry eyes—probably more acceptable than using liver! But you need to be careful with topical application of vitamin A, as there can be side effects.
In the United Kingdom, a teenager went blind recently, possibly from what could have been a serious vitamin A deficiency. All he ate was processed foods. Processed foods are poor sources of vitamin A unless they are enriched, and most are not. Fried foods are full of damaged polyunsaturated oils that cause you to need more vitamin A. It is a tragedy, but a very predictable tragedy. In the U.S., conventional milk is fortified with vitamin A so that often supplies enough to prevent frank deficiencies in children—and I worry about children who are not given milk. Children who consume raw, pastured dairy products rich in butterfat along with a serving of liver weekly or cod liver oil daily will get their vitamin A naturally. In fact, during World War II, the government of the United Kingdom had a program to make sure all of the children got their daily cod liver oil, and this continued for two or three years after the war.
I read an old report by a medical doctor who treated Civil War soldiers on the Confederate side. Due to a lack of food, they had very nutrient-deficient diets. Many of them were night blind. They also had an intolerance to daylight as their night blindness got worse. The doctor noted that they had persistently dilated pupils, which explains the photophobia. If your pupils can’t contract, then daylight will be very painful. This could be another possible sign of vitamin A deficiency to look for.
What happens to your skin if you are vitamin A deficient? A key sign is follicular hyperkeratosis, namely bumps where the hairs come out of the follicle. Hyperkeratosis is just a buildup of keratin, a hard substance similar to what is in our nails. We need a little keratin in our skin, but “hyper” means we have too much.
Dry skin, eczema, flaky scalp and acne are all signs of vitamin A deficiency. Anyone who has acne should consider vitamin A deficiency and get some vitamin A-rich foods in the diet. If you are vitamin A deficient, your hair and nails might not grow very well. Poor wound healing is another sign. In hospitals, they know that patients with wounds need vitamin A.
In my practice, one in every three or four clients has a certain degree of follicular hyperkeratosis. In his book Functional Medicine, Dr. Alan Gaby reports his own frequent finding of mild follicular hyperkeratosis on the extremities of both children and adults. Most of the patients I’ve seen have never even looked at their arms or considered what those bumps signify, and their doctors dismiss them as well.
Why does our skin need vitamin A? Vitamin A has anti-keratinizing properties as it helps differentiate our skin cells into what they are supposed to look like. All of the surfaces of our body come in contact with the environment every day and need vitamin A to deal with that contact. Many skin diseases are marked by the occurrence of hyperkeratosis, including psoriasis and acne. When we look at patients with acne, they have lower serum or plasma vitamin A and often zinc will be low. Zinc allows us to use our vitamin A so we also have to consider zinc deficiency with skin diseases, especially if someone is on a more plant-based diet or avoiding red meat or other foods that are good sources of zinc.
A colleague reported to me that the bumps on the back of her arms did not clear up until she began taking desiccated oyster, which is full of zinc. Her diet was rich in vitamin A and she ate red meat, but she still had the bumps until she got more zinc in her diet.
In moderate amounts, UV exposure from sunlight is great for skin cells, but excessive UV exposure will lower the vitamin A content of your skin. Sensible sun exposure is fine and good for your skin, but you don’t want to overdo it.
Vitamin A upregulates the collagen-specific genes that govern healing. You cannot form collagen without the right amount of vitamin A.
A possible indicator of vitamin A status is salivary pH. I see a fair number of patients with low pH (less than 6.8) in the saliva, which could indicate vitamin A deficiency. Vitamin A deficiency will lower the ability of the saliva to contain the minerals needed to buffer the acidity. This will result in acidic saliva and a tendency to form cavities. In children the tooth enamel will not form well without vitamin A. Vitamin A-deficient children will have softer teeth and greater susceptibility to cavities.
Vitamin A has a reputation for causing bone loss. A handful of observational studies have found that a higher intake (greater than 5,000 IU per day) or higher blood levels of vitamin A are associated with lower bone mineral density (BMD) or increased fracture risk.
In one study involving thirty-six thousand women, the treatment group received 400 IU of vitamin D and 1000 mg of calcium carbonate for five years. After seven years they showed a slight improvement in BMD but no statistical difference in hip fractures. Surprisingly, the treatment group had 17 percent more kidney stones.5
Other studies indicate that vitamin A is associated with a reduction in fractures. The discrepancy can be explained by the fact that vitamin A contributes to osteoporosis only in cases of vitamin D deficiency or when the ratio of vitamin A to D is massively out of balance. In animal studies, both high and low vitamin A intakes reduce BMD.
Vitamin A is important for bone synthesis; vitamin A deficiency can cause impaired bone remodeling due to unchecked function of osteoblasts as osteoblast production is decreased. In a case study of a teenager lacking vitamin A due to a very poor diet starting in early childhood, it was determined that his vision loss was due to the compression of the optic nerve from excessive bone growth in his skull. Interestingly, he did not have night blindness or eye dryness, which seems to be absent in about 5 percent of children with severe vitamin A deficiency.6
THE IMMUNE SYSTEM
One of the most important roles of vitamin A is support of the immune system. When vitamin A supplements or cod liver oil are given to populations with low vitamin A status, there is a reduction of mortality and morbidity from measles, tuberculosis, diarrheal diseases and malaria.7-11 A lot of the benefit applies to children, but researchers also observed immune support in adults as well. Most of these illnesses actually use up one’s vitamin A in the process of combatting the disease. One vitamin A researcher has recommended that the RDA of vitamin A should be set according to the amount needed for the immune system, not for vision.12 And regarding this idea of “Recommended Dietary Allowance,” I think it is better to have a little more than we need, to err on the side of having enough, than having barely what we need, but always balanced with vitamin D such as in cod liver oil.
Your immune system has three basic lines of defense. First comes the outer barrier, mainly the skin and mucosal lining of the respiratory and intestinal tracts. This is the “castle and moat,” keeping viruses and other microbes from getting into the body—our skin, the cilia in our lungs and the tight junctions in our gut keep things from entering the bloodstream.
Secondly come the cells that act quickly on a foreign invader or an antigen. I call these the “patrol officers” because they are always out there ready to grab and arrest the bad guys. These include natural killer cells, macrophages, neutrophils and dendritic cells. These first two lines of defense, called the nonspecific or innate part of the immune system, act quickly, responding in a day or two.
The third line of defense is called the adaptive immune system—I think of this third line as the “special ops”. The lymphocytes, our adaptive response, know what they are looking for and how to get rid of it. The T-cell lymphocytes perform a direct kill and B-cell lymphocytes mark the invader with an antibody. Both of these create memory cells so the next time they encounter the same pathogen they can act much more quickly. The adaptive response takes at least a week to happen if the memory cells don’t exist from a previous encounter.
Here is what happens to your immune system when you lack vitamin A. The first line of defense becomes compromised. Your skin and all the mucosal tissues become dry so they don’t create a barrier anymore—the barrier isn’t as moist and smooth as it should be. In addition, the cilia (hairs) lining our respiratory tract aren’t created normally so they don’t work well. The number of goblet cells, which produce mucus, is reduced. Our mucus becomes thicker, and that can breed germs. There is a compound in the mucus called lysozome, which is antibacterial. When we lack vitamin A, the synthesis of lysozome is reduced.
In the second line of defense, the number of natural killer cells, macrophages and neutrophils, are all reduced when you lack vitamin A—you don’t have to be deficient but just insufficient for the production of these to be reduced. Also, the ability of the macrophages to capture offenders declines and the microbicidal activity of neutrophils is reduced.
Natural killer cells are very cool. They sound tough, and they are. They are often the first cells on the job, going after invaders. Their sole purpose is to kill abnormal cells. The more vitamin A you have, the more natural killer cells you have, and the better they work. Natural killer cells are a type of lymphocyte that provides protection against viral infections and cancer. With adequate vitamin A, they can work within three days to destroy targeted cells, including cancer cells. Does this mean that all we need is natural killer cells? Certainly not! The immune system is much more complicated, but we really do want our natural killer cells to be on the job.
As for the third part of the immune system, the adaptive immune system, vitamin A increases the number of B-cells by supporting their maturation and their survival. This is essential for production of all the antibodies. It helps you convert T-cells into T-regulatory cells. These T-regs activate B-cells. Vitamin A induces gut homing, which helps your T-cells know it is time to go to the gut and take care of business there.
There is a special type of antibody called secretory IgA found in our saliva and all of our mucus. It traps pathogens and toxins by grabbing them quickly. Newborns get secretory IgA from breast milk where it is attached to the good bacteria. You can see why it is so important to breastfeed a newborn.
On top of that, vitamin A itself maintains healthy gut bacteria. In studies where they’ve made the mice vitamin A- and zinc-deficient, researchers observed that they produced lower secretory IgA. We don’t want babies born to mothers who are deficient in vitamin A and certainly, we want to encourage breastfeeding. We want the mothers to have plenty of vitamin A so their breast milk can support good immunity and gut health for their babies.
Speaking of gestational vitamin A deficiency, when mice were made vitamin A-deficient, their offspring were born with smaller lymph nodes. That is where all the T- and B-cells are made. As adults, the mice had impaired immune response, indicating that vitamin A deficiency effects are persistent into adulthood. It is hard to measure this type of thing in humans as there are so many different factors at play, but we certainly know this is happening in animals because of animal studies.
Besides keeping our immune system prepared to deal with pathogens, vitamin A allows our immune system to be tolerant. We want a tolerant immune system that doesn’t overreact to things. We want it to know when it should do its job and when it should lie low. We want it to recognize ourselves as ourselves, so we don’t develop autoimmune diseases. We want it to know when something is a non-threatening outsider because if we don’t, we get allergies. Vitamin A helps us do that by keeping our immune system from overreacting. It does the majority of this work in the gut because the gut is one of the first places where our bodies make these decisions.
Without adequate vitamin A, the body makes fewer T-reg cells and more Th17 cells, which has a proinf lammatory effect. One nutritionally-oriented doctor I follow says he uses 12,500 IU of vitamin A daily to treat allergies and autoimmune disease. I think that is a good amount. Of course, the vitamin A should never be given alone but with sources of vitamin D and zinc.
You also need to think about having a healthy gut microbiome, as this works in conjunction with secretory IgA. If you’ve got vitamin A deficiency, you’ll have a higher propensity for autoimmune disease, partly because you don’t have as many T-regulatory cells.
What else happens in your gut when you don’t have enough vitamin A? Physical changes occur. The villi become shorter and thicker. You have reduced enzyme activity, such as the disaccharidases. Do you have problems digesting carbohydrates? We need disaccharidases to digest carbohydrates so they don’t ferment, and we need vitamin A to produce disaccharidases. And with inadequate vitamin A, we make fewer goblet cells that secrete “mucins” essential in forming the mucus layer that protects our gut.
In studies of vitamin A-deficient animals, scientists have observed inflammation in the large intestine that looks like colitis, accompanied by an altered gut microbiome. Ulcerative colitis is limited to the colon but Crohn’s disease can be anywhere throughout the digestive tract, even up into the mouth. Eventually you get the transportation of toxins through the gut—the so-called leaky gut. If you have inflammatory bowel disease—either ulcerative colitis or Crohn’s disease—you don’t want to be vitamin A-deficient.
In one study patients with ulcerative colitis received 25,000 IU of vitamin A per day. They had started with a Mayo Clinic score of six to twelve, indicating moderate to severe disease progression based on the number and degree of their symptoms. There were significant decreases in symptoms in one out of three patients, and one in five had complete mucosal healing. I would not suggest that vitamin A supplementation is all a patient with ulcerative colitis should do, but it would be an important part of the protocol.
Unfortunately, these conditions are becoming more and more common these days. Have you noticed how many immuno-suppressive medications, often injectables, are advertised for these conditions? It is outrageous and scary. These are serious diseases; people’s lives are affected. They get on these medications right away, allowing almost no chance to test whether or not something as simple as vitamin A therapy plus sauerkraut or other probiotic support might have worked. Their immune systems are now suppressed instead of overreacting, but that is not the same as healing.
The other thing that we think of with an overactive immune system is allergies. We know that people with allergies often show lower levels of vitamin A in their blood. Getting adequate vitamin A during pregnancy can prevent allergies in offspring, a big problem with children today. Vitamin A along with other antioxidants such as vitamins C and E may help control asthma symptoms as well.13 One of the reasons vitamin A is effective in treating allergies is that it suppresses the activities of mast cells. Those are the ones that release the histamine that triggers an allergic response. Functional medical doctors will want to consider vitamin A as part of their protocol. A good daily protocol would be a moderately high amount of vitamin A (10,000- 20,000 IU); an appropriate amount of vitamin D (1,000-5,000 IU), depending on the patient’s sun exposure; a therapeutic probiotic (spore-based or Sacharomyces boulardii and/or fermented foods); raw milk, colostrum and/or lactoferrin; plus zinc and other needed nutrients.
An example of how vitamin A supports the immune system comes from a study on Ebola. The researchers studied patients after they were admitted to the hospital. They immediately treated some of them with 200,000 IU of vitamin A. The treated group had a mortality rate of 55 percent and the untreated 72 percent. These are significant results for such a virulent virus.
VITAMIN A AND CANCER
I don’t work with patients with active cancer diagnoses, but I think it is a good idea to make sure cancer patients are getting enough vitamin A. At the least, vitamin A will help reduce your risk for cancer—after all, vitamin A is the main nutrient for keeping cell differentiation in line. Some recent studies indicate an important role for vitamin A in preventing and treating cancer.
Colon cancer often recurs when a group of persisting cancer cells in the colon begin to multiply again. Scientists recently identified a biological mechanism that can be used to counteract these relapses. The approach activates a protein that is lost in the persisting cancer cells. The scientists were able to reactivate this protein with vitamin A, thus eliminating the cancer cells and preventing their spread. In mice with colon cancer, treatment with a form of vitamin A called retinoids blocked tumor progression and returned the colon to its normal healthy state.14
A recent study using human breast cancer cells found that vitamin A turned pre-cancerous cells back to normal healthy breast cells.15
People whose diets included high levels of vitamin A had a 17 percent reduction in risk for getting the second-most-common type of skin cancer, as compared to those who ate modest amounts of foods and supplements rich in vitamin A.16
Vitamin A also shows promise in the treatment of pancreatic cancer. In a healthy pancreas, cells called stellate cells exist in a dormant state, storing abundant supplies of vitamin A. As colon cancer progresses, these stellate cells become activated in response to signals from the tumor and lose their vitamin A content. These activated stellate cells form dense connective tissue around the tumor, which is then used by cancer cells to spread to other parts of the body. The tissue also limits the ability of cancer-fighting drugs to penetrate the tumor. In the new study, researchers found that it was possible to switch off these stellate cells, potentially preventing the formation of the tissue around the tumor, through a process involving vitamin A.17
In another pancreatic cancer study, the addition of high doses of a form of vitamin A made chemotherapy more successful. The results were so promising that a clinical trial is now underway. According to the lead author, “Pancreatic cancer is extremely hard to treat by chemotherapy, so this finding is important because vitamin A targets the non-cancerous tissue and makes the existing chemotherapy more effective, killing the cancer cells and shrinking tumors.”18
These studies used only vitamin A, and not vitamin A combined with vitamin D, as in cod liver oil or liver, which one might expect would be even more effective.
VITAMIN A AND METABOLISM
An explosion of research during the past few years has revealed some new roles for vitamin A. For example, we have learned that as an electron-carrying compound, vitamin A plays a key role in glycolysis, the creation of energy from glucose. A lot of us are trying to be fat burners, and that’s great, but we should still be able to do glycolysis well. In animal studies, when animals are deficient in vitamin A, they have reduced levels of ATP, the currency of energy. In addition, vitamin A deficiency reduces the storage of glycogen in the liver, which is going to make you more prone to hypoglycemia and/or more frequent hunger, as your body isn’t able to draw glucose from your glycogen when you need it.
Gestational vitamin A deficiency in animals reduces the beta cell mass of the offspring. The beta cells are where we make insulin. You don’t want to be behind the eight ball, born with fewer insulin-producing cells. That’s just a recipe for diabetes in the future and could partly explain the recent increase in lean individuals who are developing type 2 diabetes.19
You need vitamin A for making thyroid hormones and without vitamin A you can’t use those hormones as effectively.
Your sex hormones need vitamin A. Males need vitamin A to make testosterone and females need vitamin A to make progesterone. Your growth hormones need vitamin A. That is because hormones work in the nucleus of the cell, interacting with and being regulated by vitamin A. Vitamin A is basically like a hormone. Boys who are not growing well need to be on vitamin A and iron, and sometimes zinc so they can make testosterone and growth hormones; this nutrient combination has been show to be as effective as the administration of testosterone.
Finally, vitamin A might actually have something to do with preventing Alzheimer’s and maintaining cognition. This discovery comes from preliminary research on animals, but the relevance to people is clear. In fact, problems can start as early as in the gestational period; vitamin-A deficient offspring may lack good memory skills and the ability to learn, which persists into adulthood.
VITAMIN A FOR PREGNANCY
You definitely want to have plenty of vitamin A during pregnancy! Unfortunately, most health practitioners are afraid of vitamin A during pregnancy. This fear is based on a 1995 study by Rothman and others, which suggested that over 10,000 IU of vitamin A daily in the first eight weeks of pregnancy increases risk of neural crest defects. All seven cases involved intakes of over 10,000 IU from supplements, not from food, with an average intake of 21,000 IU.20 Chris Masterjohn21 and Mary G. Enig22 have written about the flaws in the Rothman study and noted other studies that indicate that adequate levels of vitamin A during pregnancy result in fewer birth defects. But the Rothman study set the stage for the current fear of vitamin A for pregnant women, and it has resulted in practitioners saying that pregnant women should get no preformed vitamin A at all—and this in the teeth of all we are learning about the need for vitamin A for normal fetal development. For this unfounded reason, almost all prenatal vitamins contain only beta-carotene, not retinol.
Are pregnant women in danger of getting too much vitamin A or too little? A recent study showed that one-tenth of women at delivery in Nebraska were frankly deficient in vitamin A. That to me is significant. In Brazil, the number was one-fifth, so the U.S. is not that different from a Third World country.23 If you look at the numbers, vitamin A status of our mothers is not much better than in Nigeria. We have 73 percent of infants, born deficient. It isn’t abnormal to have low vitamin A in infants but if you look at the mothers, 10 percent of them were deficient in vitamin A at birth, and 41 percent were insufficient, so 50 percent had less than sufficient amounts in their bodies at birth.
Dr. Price knew that vitamin A was necessary for reproduction in animals and, without it, bad things happen in people, such as miscarriage or even complete infertility. Low vitamin A also leads to all sorts of birth defects. This is from the Nutrition and Physical Degeneration.
One of the big concerns with vitamin A deficiency during pregnancy is lung problems in the babies, which can persist for life. Both early and late gestational vitamin A deficiency have negative effects, such as defective alveoli and a predisposition to respiratory diseases. Human lung development starts in the fifth week of gestation and continues during the first few years.
In the gut, vitamin A deficiency during gestation results in the production of fewer villi, which can presage digestive problems throughout life.
Embryonic vitamin A deficiency causes “grossly thinned ventricular wall with concurrent defects in ventricular septation [in hearts of newborn mice].”24 The prevalence of this type of defect is increasing—today afflicting about 1 percent of all babies. It often requires surgery to correct the ventricular septal defect—basically a hole in the heart. The other thing that you see is premature babies having bronchopulmonary dysplasia, where the lungs don’t work well and the baby needs oxygen. This also is associated with vitamin A deficiency.
After birth, babies must get vitamin A from breastmilk as they are generally born with low liver stores. Colostrum will be rich in vitamin A only if the mother has good intake. The mom’s colostrum is supposed to be a rich shot of nutrients, and it is supposed to be full of vitamin A. If that mom doesn’t have it then neither does the colostrum.
After weaning, the infant is at greater risk of vitamin A deficiency. If the baby is born to a mother with low vitamin A, then it is only going to get worse. Unfortunately, we don’t know how this will affect the baby. We do know that the secretory IgA in the gut needs vitamin A.
They used to give mothers in developing countries 200,000 IU of vitamin A right after birth, but they no longer do that. Supplementation of lactating women with β-carotene has relatively little effect on breastmilk vitamin A content. In infants of mothers supplemented with 200,000 IU true vitamin A after birth, there was a significantly lower incidence of respiratory tract infections and fever.25
Vitamin A deficiency can lead to complete lactation failure in animals. Could this be a reason why some mothers are not able to produce enough or any milk?
In spite of the Rothman study, a number of researchers have expressed concern about vitamin A deficiency in pregnant women. “Vitamin A is essential for reproduction, and deficiencies and excesses may result in embryonic loss and/or congenital defects. Retinoids [vitamin A] are recognized as important regulators of vertebrate development, cell differentiation and tissue function. Previous studies, performed both in vivo and in vitro, indicate that retinoids influence several reproductive events, including follicular development, oocyte maturation and early embryonic development.”25
“The question about the safety of vitamin A use in pregnancy remains a complex and unresolved issue, even though it is recognized that vitamin A plays an important role in normal embryonic growth and development.”26
“Of particular concern are [pregnant women] in the latter half of pregnancy when nutritional demands are high…and the risk of developing night blindness and other adverse health outcomes is greatest. . .”26
Liver is an ideal food for pregnant women. No birth defects have been reported with higher intakes of vitamin A from food sources. It is really important to know that there has never been a report of fetal malformation or birth defect from a woman eating liver. Now with that said, I wouldn’t encourage women to eat liver daily but only once a week. Four to six ounces is plenty. Vitamin A from liver produces a smaller and delayed rise in serum retinol levels versus vitamin A from retinyl esters.27
For women who refuse to eat liver or other vitamin A-rich foods, the evidence suggests that a low-dose vitamin A supplement may be protective against birth defects.28 An intake of 2,500-5,000 IU per day will support a healthy pregnancy in a woman who has been following an overall nourishing diet prior to conception.29 Women need vitamin A early in pregnancy, not just toward the end, when they are getting ready to lactate.
Vitamin A and D together are best; the combination is more effective at supporting robust immunity and reduces any potential toxicity of either one at higher intakes. In addition, vitamin K2 (from food) enhances the protective actions of A and D.30
In my practice I work with regular people, mostly women, for whom sources of vitamin A are seldom included in the diet. It’s rare to find a client who knows about the Wise Traditions diet. Not many people eat liver or take cod liver oil. People are afraid to eat eggs because they contain a lot of cholesterol, and they avoid butter because it contains saturated fat. Of course, I encourage my clients to eat these foods, even more so if they are trying to conceive, are pregnant or are lactating.
Can we get too much vitamin A? Yes, that is possible. I don’t think you need to eat liver more than once a week, unless you know that you are actually deficient in vitamin A. If you have fatty liver, you are probably not going to be able to store any more vitamin A in your liver, so limit your preformed vitamin A intake to at most 3,000 IU per day. If you have elevated triglycerides or have taken a lot of supplements containing around 50,000 IU of vitamin A for a few years, you could be getting too much. Be careful if you are doing water-miscible or emulsified forms as they can be toxic at one-tenth the recommended dose.
What are the signs of vitamin A excess? They include nausea, fatigue, headaches, dry skin, joint pain, muscle pain, anorexia, hair loss, brittle nails, elevated liver enzymes, high blood calcium and bone abnormalities. The risk of vitamin A toxicity is higher in situations of liver disease or protein and zinc malnutrition. Fortunately, these symptoms are reversible with discontinuation of vitamin A sources.
Deficiency is worse. All sorts of bad things can happen if a woman is deficient in vitamin A. I’ve seen this so many times in my own practice. Lots of things improve when women get adequate vitamin A. They get their periods back. Their cervical mucus returns. They are getting pregnant when they couldn’t before. Of course, we work on improving their intake of other important nutrients besides vitamin A, but we know these things are affected by whether or not a woman gets enough vitamin A. We need vitamin A to make progesterone, and I have seen that vitamin A can help treat endometriosis.
And if someone is considering in vitro fertilization (IVF) as a means to conceive, one study shows that women are more likely to have a better quality embryo if they have adequate levels of vitamin A in their bodies.31
During pregnancy, for those who won’t eat liver, I recommend somewhere between 2,500-5,000 IU daily from a supplemental source (vitamin A from fish liver oil, cod liver oil or desiccated liver supplements, for example). The Foundation recommends 20,000 IU daily from food sources (including cod liver oil) starting before pregnancy. As a licensed dietitian, I can’t recommend more than 10,000 IU in my practice because of the Rothman study and clinical guidelines. Therefore I tend to be fairly conservative, while teaching women how to top off their vitamin A stores prior to conception.
Vitamin A is truly A-Mazing! Unfortunately, due to a lot of misplaced fear and misinformation, people—especially pregnant women—are not getting enough. From my experience on the front lines of nutritional guidance, I believe that vitamin A is the single most important yet unrecognized nutrient. Its intake will determine whether we enjoy robust good health or suffer from the ongoing repercussions of borderline malnutrition.
- Timoneda J and others. Vitamin A deficiency and the lung. Nutrients. 2018 Aug 21;10(9).
- Weston A. Price. Nutrition and Physical Degeneration, 1945.
- Blomhoff R and Drevon CA. Fat-soluble vitamins in clinical practice. Tidsskr Nor Laegeforen. 1995;115(4):481-5.
- International expert on Vitamin A, Alfred Sommer, MD, Dean Emeritus, Johns Hopkins School of Public Health quoted in Vitamania: How Vitamins Revolutionized the Way We Think About Food by Catherine Price.
- Jackson RD and others. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006; 354(7):669-83.
- Zayed and others. Unilateral compressive optic neuropathy due to skull hyperostosis secondary to nutritional vitamin A deficiency. Clin Cases Miner Bone Metab. 2015;12(1):75–77.
- Villamore E and Fawzi WW. Effects of vitamin A supplementation on immune responses and correlation with clinical outcomes. Clin Microbiol Rev. 2005;18(3):446- 464.
- Mayo -Wilson and others. Vitamin A supplements for preventing mortality, illness, and blindness in children aged under 5: systematic review and meta-analysis. Br Med J. 2011;343:1-19.
- Vitamin A administration reduces mortality and morbidity from severe measles in populations nonendemic for hypovitaminosis A. Nutr Rev. 1991;49(3):89-91.
- Karyadi E and others. A double-blind, placebo-controlled study of vitamin A and zinc supplementation in persons with tuberculosis in Indonesia: effects on clinical response and nutritional status. Am J Clin Nutr. 2002;75:720–727.
- Semba RD. Vitamin A and immunity to viral, bacterial and protozoan infections. Proc Nutr Soc. 1999;58(3):719- 727.
- Ahmad SM and others. Markers of innate immune function are associated with vitamin A stores in men. J Nutr. 2009; 139:377-385.
- Riccioni G and others. Antioxidant vitamin supplementation in asthma. Ann Clin Lab Sci. 2007;37(1):96-101.
- Paloma Ordóñez-Morán and others. HOXA5 counteracts stem cell traits by inhibiting Wnt signaling in colorectal cancer. Cancer Cell, 2015; 28 (6): 815.
- Maria Arisi and others. All trans-retinoic acid (ATRA) induces re-differentiation of early transformed breast epithelial cells. International Journal of Oncology, 2014.
- Jongwoo Kim and others. Association of vitamin A intake with cutaneous squamous cell carcinoma risk in the United States. JAMA Dermatol, 2019.
- Antonios Chronopoulos and others. ATRA mechanically reprograms pancreatic stellate cells to suppress matrix remodelling and inhibit cancer cell invasion. Nat Commun, 2016; 7.
- Elisabete F. Carapuça and others. Anti-stromal treatment together with chemotherapy targets multiple signalling pathways in pancreatic adenocarcinoma. The Journal of Pathology, 2016 Jul;239(3):286-96.
- George AM and others. Lean diabetes mellitus: an emerging entity in the era of obesity. World J Diabetes. 2015;6(4):613-620.
- Rothman KJ and others. Teratogenicity of high vitamin A intake. N Engl J Med. 1995 Nov 23;333(21):1369-73.
- Hanson C and others. Status of retinoids and carotenoids and associations with clinical outcomes in materinal-infant pars in Nigeria. Nutrients. 2018; 10(9): 1286.
- Sucov HM and others. RXR alpha mutant mice establish a genetic basis for vitamin A signaling in heart morphogenesis. Genes Dev. 1994 May 1;8(9):1007-18.
- Allen LS and Haskell M. Vitamin A requirements of infants under six months of age. Food Nutr Bull. 2001;22(3):214.
- Tanumihardjo SA and otheres. Biomarkers of nutrition for development (BOND)-vitamin A review. J Nutr, 2016; 146(9): 186S-1848S.
- Dibley MJ and Jeacocke DA. Safety and toxicity of vitamin A supplements in pregnancy. Food Nutr Bull. 2001; 22(3).
- Khoury MJ and others. Vitamin A and birth defects [letter]. Lancet 1996;347:322.
- Teratology Society Position Paper: Recommendations for vitamin A use during pregnancy. Teratology. 1987; 35:269–275. Available at: https://www.teratology.org/pubs/vitamina.htm.
- Pauli SA et al. Analysis of follicular fluid retinoids in women undergoing in vitro fertilization: retinoic acid influences embryo quality and is reduced in women with endometriosis. Reprod Sci. 2013;20(9):1116-1124.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly journal of the Weston A. Price Foundation, Spring 2020