The new USDA/HHS Guidelines are not entirely bad —for example, they recommend limiting added sugars, tossing the hydrogenated oils, and even limiting fruit juice, and they advocate sidewalks, parks, and safe neighborhoods as ways to provide people with opportunities to increase physical activity — but they provide an awfully strange definition of the phrase “nutrient dense” that leads them to advocate a diet that is anything but.
The term “nutrient dense” indicates that the nutrients and other beneficial substances in a food have not been “diluted” by the addition of calories from added solid fats, added sugars, or added refined starches, or by the solid fats naturally present in the food.
So what, then, are the “nutrient-dense” foods?
All vegetables, fruits, whole grains, fat-free or low-fat milk and milk products, seafood, lean meats and poultry, eggs, beans and peas (legumes), and nuts and seeds that are prepared without added solid fats, sugars, starches, and sodium are nutrient-dense.
Somehow “the solid fats naturally present in the food” reduce the food’s nutrient density by this definition, so suddenly meats are only nutrient-dense if they are lean and milk products are only nutrient-dense if the are fat-free or low-fat.
It would seem that the term “nutrient-dense” should refer to the density of nutrients in a food, adjusted for bioavailability. This could be measured per gram, per calorie, or per unit volume, depending on a person’s particular needs. Since nutrients are essentially worthless if they aren’t absorbed and utilized, the term should incorporate bioavailability.
The USDA considers other factors that have nothing to do with nutrient content or bioavailability to trump these issues.
A strong body of evidence indicates that higher intake of most dietary saturated fatty acids is associated with higher levels of blood total cholesterol and low-density lipoprotein (LDL) cholesterol. Higher total and LDL cholesterol levels are risk factors for cardiovascular disease.
Notice the careful wording. Associated with. Risk factors.
The use of this careful wording is somewhat ironic, because the document provides a clear warning against confusing association with causation.
When considering the evidence that supports a recommendation, it is important to recognize the difference between association and causation. Two factors may be associated; however, this association does not mean that one factor necessarily causes the other. Often, several different factors may contribute to an outcome. In some cases, scientific conclusions are based on relationships or associations because studies examining cause and effect are not available. When developing education materials, the relationship of associated factors should be carefully worded so that causation is not suggested.
So it is important to use careful wording so as not to confuse association and causation, but not so important to recommend dietary changes that are based on solid evidence of causation? But I digress.
There are, of course, nutrients within the water-soluble fraction of milk and within lean meat that would be “diluted” by the inclusion of their natural fats, but there are also unique nutrients that are found in these fats, and the fats help increase the bioavailability of fat-soluble nutrients.
Although there is no one source from which Americans get most of their saturated fat, the leading source according to this document is cheese.
As discussed in the Rotterdam Study, the main source of vitamin K2 in modern diets is also cheese. In my 2007 article, “On the Trail of the Elusive X Factor,” I reviewed a number of lines of evidence suggesting that vitamin K2 is a potent weapon against heart disease.
The clear association between vitamin K2 and “the solid fats naturally present in the food” can be seen by looking at the vitamin K2 content in various types of dairy products.
Similar results would be found for other fat-soluble nutrients.
Fat also increases the absorption of fat-soluble nutrients. For example, a 2006 study found that a bagel with low-fat cream cheese containing 2.4 grams of fat (6% of calories) increased the absorption of vitamin E from fortified apples, while a bagel with regular-fat cream cheese containing 11 grams of fat (21% of calories) increased it even more.
A 2004 study found similar results for carotene absorption from a salad using fat-free, low-fat, or regular-fat salad dressing. The regular-fat dressing added 28 grams of fat to the salad, so the calories in the meal must have been mostly from fat.
Black triangles represent the fat-free salad, while white circles represent the low-fat salad and black circles represent the regular-fat salad.
These studies provide no evidence of a “ceiling” to the fat effect. The highest fat meal in both studies provided the best absorption of fat-soluble nutrients.
An 2000 animal study found that carotene absorption was nearly two times higher with olive oil than with corn oil, suggesting perhaps that the polyunsaturated fatty acids in corn oil promote oxidative stress in the intestine and thereby decrease carotene absorption. So much for the case against “solid fats.”
To its credit, the USDA and HHS do list eggs among its nutrient-dense foods, and eggs are one of the best sources of choline.
But how much credit do these institutions deserve? Not much.
Although eggs are considered nutrient-dense, that doesn’t mean we should eat much of them, they say. This document recommends we eat 0.4 ounces of eggs per day, which allows us about one egg every five days.
Dietary cholesterol has been shown to raise blood LDL cholesterol levels in some individuals. However, this effect is reduced when saturated fatty acid intake is low, and the potential negative effects of dietary cholesterol are relatively small compared to those of saturated and trans fatty acids. Moderate evidence shows a relationship between higher intake of cholesterol and higher risk of cardiovascular disease. Independent of other dietary factors, evidence suggests that one egg (i.e., egg yolk) per day does not result in increased blood cholesterol levels, nor does it increase the risk of cardiovascular disease in healthy people. Consuming less than 300 mg per day of cholesterol can help maintain normal blood cholesterol levels. Consuming less than 200 mg per day can further help individuals at high risk of cardiovascular disease.
Actually, consuming three to four eggs per day has little or no effect on blood cholesterol levels in about 70 percent of people. In nearly 30 percent of people, total cholesterol increases, but HDL-cholesterol increases as much as LDL-cholesterol, and LDL particle size improves. A 2006 review of randomized controlled trials feeding eggs suggested that three to four eggs per day made blood lipid profiles less “atherogenic” in about 99 percent of healthy adults (ethical considerations, of course, would demand you only feed this “extreme” number of eggs to healthy people).
An egg every five days? So much for the choline.
It would seem that a diet lacking in organ meats, egg yolks, and saturated fats would be missing some key nutrients, and could hardly be considered “nutrient-dense” unless one simply ignored the whole class of fat-soluble nutrients.
But hey, if we’re going to confuse association with causation and redefine nutrient density to incorporate factors that have nothing to do with nutrient density, we might as well start ignoring nutrients too.
But if we’re going to do that, why reinvent the wheel? It would be more efficient to just use the system for ranking nutrient density that Dr. Joel Fuhrman already developed.
Read more about the author, Chris Masterjohn, PhD, here.