What’s causing obesity? I can’t believe it’s not butter.

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January 11, 2013 by lschoenfeld

One of the major themes I heard come up over and over during our three days in Washington D.C. was the emphasis on “science-based” nutrition policy. From the Dietary Guidelines themselves, to the policies created to enact the guidelines, to the food manufacturers’ efforts to create product based on those guidelines, it would seem that taking an evidence-based approach is the gold standard for nutrition in our country. After all, why would we want to enact national nutrition policies that cost billions of dollars but don’t actually work?

The major issue I saw over the three days was that most of the speakers were under the impression that their understanding of nutrition science was infallible and completely up-to-date. I heard statements like “the tenets of nutrition are stable,” that “the science of what we should eat is almost irrelevant,” and that “we know what people should be eating, but we don’t know how to get them to eat that way.” It seems that most nutrition professionals, at least in the public health and policy world, assume that our understanding of what makes a nutritious human diet is 100% accurate and complete, and that the only issue is that Americans are ignoring our perfectly sound advice. But is this the total reality of the situation? Personally, I think not.

I would argue that one of the biggest problems facing nutrition in this country is the fact that not only do we not understand what dietary factors truly cause obesity, but that we are enacting nutrition policy based on dietary beliefs that are outdated and, frankly, often inaccurate. An example that was used consistently this week was the issue of dairy fat, and how policy makers and public health nutritionists are doing their best to ensure that Americans, particularly children, are only consuming low fat or fat-free milk. These professionals believe that full fat dairy products, and saturated animal fats in general, are completely unhealthy and are significantly contributing to the obesity and chronic disease epidemic in this country. This could not be farther from the truth.

Dairy Fat: Public Health Enemy #1?

A recent article in Today’s Dietitian, the magazine published by the Academy of Nutrition and Dietetics, explained that the saturated fat found in dairy may actually be health promoting, and that the message to drink low-fat milk products is inaccurate. There are hundreds of compounds in milk fat, such as distinct fatty acids and fat-soluble vitamins, that may play a role in supporting our health. For example, trans-palmitoleic acid, a fatty acid found in full fat milk, cheese, yogurt, and butter, may substantially reduce the risk of type 2 diabetes and other metabolic disorders. Other research has found that that people with the highest levels of milk fat biomarkers in their blood, suggesting they consumed the most dairy fat, were actually at a much lower risk of heart attack.

Furthermore, dairy is a food recommended by the dietary guidelines due to its high calcium content. But research shows that calcium requires both vitamin D and vitamin A, as well as a newly emphasized form of vitamin K (called vitamin K2), to properly assimilate the calcium for the promotion of bone growth. Did you know that dairy fat, particularly from grass-fed cows, is one of the highest sources of vitamin K2 in our diet? Vitamin K2 is an essential fat-soluble vitamin that works synergistically with vitamins A and D to create calcium binding proteins, which ensure the proper placement of calcium in our bones rather than our soft tissues (eg. our arteries), preventing both atherosclerosis and osteoporosis. Without adequate vitamin K2, we cannot properly use the calcium found in dairy for healthy bone growth, and that unused calcium may end up hardening our arteries instead.

It is important to note that vitamin K2 specifically, and not the vitamin K1 found in leafy greens and other plant foods, that is protective against atherosclerosis and osteoporosis. So I would like to question policy makers where they expect our nation’s children to get vitamin K2 from if dairy fat is stripped from our diets. Will we be serving goose liver in school lunches? How about natto? Maybe copious amounts of egg yolks? Could it be that the deficiency of vitamin K2 in children’s diets is causing toddlers to display signs of cardiovascular disease at such young ages? Perhaps not, but we don’t know for sure.

As you can see, the evidence strongly supports the health protective effects of dairy fat. And yet our nutrition policies are pushing hard to get dairy fat out of our diets, and particularly out of children’s diets. The belief that dairy fat is directly contributing to childhood obesity, or that switching to skim milk after age 2 will improve our children’s health in any way, requires blatant denial of the scientific evidence supporting the consumption of whole-fat dairy products. Or perhaps just ignorance of human nutrition and biochemistry.

While there’s no way to know what the health impact of eliminating dairy fat, and other animal fats, from the American diet will be, I think it brings up another important theme that came up several times over the three days: the law of unintended consequences. For as much as public health nutritionists honestly believe they’re helping their constituents lead healthier lives, many of the nutrition policies developed in the past 20-30 years have not only not made us any healthier, but may have even left us worse off than we started before the Dietary Guidelines existed. It doesn’t seem like anyone in the government is actually evaluating the long term health effects of the shift in our diet composition as a result of the recommendations they’ve made. Why have obesity rates increased in velocity ever since the Dietary Guidelines were enacted? Sure, correlation doesn’t prove causation, but it’s definitely something to consider. Why do we continue promoting the same policies if they’ve never actually worked, and may actually be causing harm?

Thanks to fellow UNC student Adele Hite, MPH-RD for this image.

Since saturated fat and dietary cholesterol have never been shown to cause heart disease, diabetes, or obesity, why are we still working so hard to reduce Americans’ intake of these nutrients? Since the evidence shows that dairy fat is health-protective, why aren’t we providing whole milk – not high sugar flavored skim milk – in our children’s school lunches? Some research even shows that calorie restriction and long term dieting actually leads to weight gain over time, thanks to the chronic psychological stress it causes, so why are we pushing our clients to count calories so meticulously? Why are nutrition professionals resting on their laurels and not questioning their understanding of human nutrition as the available science continues to improve?

The most important thing I learned this week is that there is a serious knowledge deficit in the world of public health when it comes to understanding what constitutes a truly health-promoting diet. I realized this week that if our country’s overall health is ever going to seriously change, we need to challenge conventional ‘wisdom’ about what a nutrient-dense diet is. Believe it or not, animal foods – and animal fats – can be highly nutrient-dense as well, not just fruits and vegetables. The truth is, the world of obesity research is ever changing and expanding, and scientists are constantly learning more about the factors that truly contribute to obesity and its related diseases – and I can tell you pretty confidently, it’s not saturated fat, dietary cholesterol, or full-fat dairy products.

If public health nutritionists continue their misguided attack on certain innocuous dietary components, I believe the health of our country will continue to suffer, and will likely even get unintentionally worse. Therefore, I see it as my responsibility, as some of the speakers pointed out, to continue to be persistent and advocate for better nutrition guidelines based on evidence rather than conjecture or conventional (but incorrect) belief. I hope that my role as a public health nutritionist will be to eradicate misconceptions and misunderstandings about what constitutes a healthy diet, and find a way to better educate my colleagues about the ever-changing world of nutrition science. It worries me that a marketing executive knows about our country’s dietary choline deficiency but that as an MPH-RD student, I’ve never even heard choline discussed as an essential nutrient in class.

I hope one day, when I’ve entered the world of public health nutrition, I can help to address that gap in knowledge, and ensure that Registered Dietitians are truly the nutrition experts we purport to be.