True vitamin A is a vitamin that occurs only in animal fats. In indigenous societies, pregnant women consumed special foods rich in vitamin A–such as liver, spring butter and fish eggs–in a conscious effort to produce healthy, well-formed children. Modern research completely validates these traditions.
In a recent paper,1 Maija H. Zile, of the Department of Food Science and Human Nutrition, Michigan State University, details the role of vitamin A in fetal development. Working with bird and mouse embryos, she and other researchers have determined that the vitamin A requirement begins at the time of formation of the primitive heart and circulation, and the development of the hindbrain, a period that corresponds to weeks 2-3 in humans. Without vitamin A, the embryo succumbs to gross abnormalities of the heart and is aborted.
Each organ system begins development during a specific window of time. Vitamin A regulates the differentiation of the primitive cells into cells specific to each organ system, in essence signaling to the genes their marching orders so they “know” where to locate themselves and what kind of tissues to become. If vitamin A is lacking during any of these windows, the organs develop abnormally or not at all.
The major target tissues of vitamin A deficiency include the heart, central nervous system, the circulatory, urogenital and respiratory systems, and the development of the skull, skeleton and limbs. Vitamin A deficiencies during the period when any of these systems begin specialization can result in abnormalities and defects.
According to Zile, even partial vitamin A deficiency affects the sensitive developing central nervous system; it plays a key role in the development of the visual system, the retina, the inner ear, the spinal cord, the craniofacial area including the pharyngeal and branchial arches and the thymus, thyroid and parathyroid glands.
During mid-gestation, vitamin A is required for fetal lung development. In vitamin A-deficient animals, congenital malformations in the urogential system occur.
Most interesting is new research on the effect of vitamin A on kidney development. Vitamin A deficiency results in a reduced number of nephrons in the kidney. Lower numbers of nephrons mean the kidneys will not work at optimal levels and may doom the individual to dialysis later in life.2
Another fascinating avenue of research has shown that vitamin A holds the key to what scientists call the “holy grail” puzzle of developmental biology: the existence of a mechanism that ensures that the exterior of our bodies is symmetrical while the inner organs are arranged asymmetrically. Researchers at the Salk Institute have found that vitamin A provides the signal that buffers the influences of asymmetric cues in the early stages of development, and allows these cells to develop symmetrically. In the absence of vitamin A, the exterior of our bodies would develop asymmetrically, with the result being that our right side would be shorter than the left side.3
After the formation of all the organ systems, vitamin A supports their growth. Chronic vitamin A deficiency during pregnancy compromises the liver, heart and kidney and impairs lung growth and development during the last weeks of gestation.4
Unfortunately, FDA and other agencies warn pregnant women to avoid foods like liver and cod liver oil, claiming that too much vitamin A from these foods can cause birth defects. The study usually cited in support of these warnings was carried out in 1995 at the Boston University School of Medicine and published in the New England Journal of Medicine.5 In the study, researchers asked over 22,000 women to respond to questionnaires about their eating habits and supplement intake before and during pregnancy. Researchers found that cranial-neural crest defects increased with increased dosages of vitamin A; but neural tube defects decreased with increased vitamin A consumption, and no trend was apparent with musculoskeletal, urogenital or other defects.
This study is a poor rack on which to hang the myriad warnings that have kept pregnant women from eating liver and taking cod liver oil. Researchers made no distinction between synthetic vitamin A derived from multivitamins and processed food like margarine, and natural vitamin A from food; nor did they take blood samples to determine vitamin A status. Food recall surveys are a notoriously inaccurate method of determining nutrient intake.
Subsequent studies found that high levels of vitamin A did not increase the risk of birth defects. A 1998 study from Switzerland looked at vitamin A in pregnant women and found that a dose of 30,000 IU per day resulted in blood levels that had no association with birth defects.6
A 1999 study carried out in Rome, Italy found no congenital malformations among 120 infants whose mothers consumed an average of 50,000 IU of vitamin A per day.7 Some participants consumed up to 300,000 IU vitamin A daily during pregnancy with no birth defects in the offspring. An average of 50,000 IU vitamin A per day is consistent with our recommendation of cod liver oil to supply 20,000 IU per day plus additional vitamin A in liver, butter, seafood and egg yolks.
- J Nutr. 2001;131:705-708.
- Nephr Dial Trans. 2002 Sept;17(Suppl9):78-80.
- Brit J Nutr. 2000 July;84(1):125-132.
- NEJM. 1995 Nov 23;333(21):1414-5.
- Int J Vit Nutr Res 1998;68(6):411-6.
- Teratology. 1999 Jan;59(1):1-2.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Summer 2005.🖨️ Print post
” Researchers made no distinction between synthetic vitamin A… and natural vitamin A from food”
So it sounds as if the synthetic Vitamin A may have been a contributing factor to the neural defects? If so there should be warning for pregnant women on the cod liver oils listed on this site under “good” as they contain synthetic vitamin A. Also, even though there is no conclusive evidence that high dose vitamin A causes defects in pregnant women, high doses of vitamin A does cause defects in pregnant animals (teratology.org).
From what I remember Weston Price did his studies on based on the vitamins in food. Not synthetic vitamins. This along with the fact that high levels of EPA (found in cod liver oil) when not balanced with arachidonic acid may cause hemorrhaging would make me put a blazing red warning about cod liver oil for pregnant women.
Why not just recommend a good food-based prenatal like Vitamin Code and encourage meat, eggs, and sunshine?
I would appreciate a reply!
As a nutritionist, one reason I would not encourage women to rely on prenatal vitamins alone for vitamin A is that they contained only precursors to vitamin A, or beta carotene. Many people cannot make the conversion from those precursors to usable vitamin A for various reasons. The risks for vitamin A deficiency outweigh the risks of high doses of true viamint A from animal foods, in my opinion (I am currently pregnant myself). But really women just need the information so that they can make the decisions themselves.
As to the animal studies, they can give us a glimpse into possible human outcomes, but that isn’t always the case. For instance, mice don’t metabolize certain things in the way humans do — they lack some of the same pathways. So there are limitations in those studies unfortunately.
I started taking Vitamin A several months ago. I was taking 25,000 IU of synthetic Vitamin A each day then I found out I was pregnant. I immediately stopped taking them because my doctor told me that it would cause deformations to the fetus. I am currently pregnant and hoping that everything is okay. What is your opinion?
If you are eating meat, eggs, and butter, you will obtain plenty of arachidonic acid. I think it makes more sense to recommend a surf and turf style diet. Take your cod liver oil from the sea animals while obtaining the dairy and meat from the land animals.
Crystal Hewitt says
Please, show me how to get 20,000 IU of vitamin a ?
Casey wan says
It’s so refreshing to read about Dr Price’s work and his foundation but, it’s a crying shame that the medical field of science even, to this day of advanced technology strongly abide to, and fiercely protect the official guidelines that’s already drawn up and laid down to follow for the gullible public. I’m getting carried away so I best terminate for now and thank you!
Can one relies on EPA (100mg) and DHA ( 480mg) vitamin from a good brand ( eg brand MorDHA) instead of an intake of Cod liver oil which is indeed not recommended by doctors in Sweden ? They also don’t recommend liver but I kept having it once a month during my pregnancy .. I would appreciate an answer – many thanks
Maureen Diaz says
We do not recommend relying on isolated nutrients, nor those which are synthetically produced. Thus we strongly recommend acquiring our nutrients from traditional food sources, including high-quality cod liver oil.Unfortunately the medical and pharmaceutical industries have hijacked good, sound nutritional advice in favor of allopathic modalities which come with many concerns for health outcome. You can find several articles covering the benefits of cod liver oil by searching our website, including this article which is a great starting point!
Avigail Roberg says
Thank you. I loved the article as cod liver oil is a subject that I constantly research as I (as a mother of nine) have developed a pure, premium and kosher cod liver oil.
So thanks for th aarticle and just thought you may appreciate knowing about the Vassaburg Kosher Cod Liver Oil.
Hello, I am 5 months pregnant I have been taking carlson norwegian cod liver 1tea spoon a day. After reading articles regarding the retinyl palmitate and how its processed. Should I be worried?