According to a new study, we're focusing on the wrong fat.
A review of past research just published in the medical journal BMJ found that eating a diet rich in saturated fat — found mostly in meat and full-fat dairy — is not linked to cardiovascular disease, coronary heart disease, ischemic stroke, type 2 diabetes or overall mortality in healthy adults.
By contrast, trans fat, which is found in processed food, was associated in the analysis with a 21 percent increased risk of coronary heart disease, a 28 percent increased risk of death by coronary heart disease and a 34 percent increase in death by any cause.
This latest paper marks the seventh meta-analysis in 10 years to show that saturated fat intake is not linked to chronic disease. So why are nutrition scientists still recommending that the nutrient be limited? According to experts, these study results don't tell the whole story.
Saturated Fat Still Isn't 'Good' For You
The Dietary Guidelines Advisory Committee, which is tasked with advising the federal government on food policy, still recommends that Americans limit saturated fat intake to no more than 10 percent of daily calories in order to keep chronic illness at bay.
It turns out, there's a good reason for that: Randomized trials, which provide stronger evidence of cause and effect, show that lowering saturated fat intake reduced the risk of a cardiovascular event by 17 percent. That's because saturated fat is thought to raise LDL cholesterol levels in the blood, which can build up in your blood vessels and raise your risk of heart attack.
What's more, saturated fat often keeps bad company. It's very easy to find it in processed foods, explained Frank Hu, a professor of nutrition and epidemiology at the Harvard School of Public Health who also served on the DGAC.
"Those nutrients can be easily added to the food supply and can affect the quality of overall diet,” Hu said.
Instead of exonerating individual types of fat, we should focus on a dietary pattern rich in vegetables, fruit, whole grains, fish, legumes and nuts. Meanwhile, foods like dairy products should be eaten at a moderate level, and red and processed meats, sugar-sweetened food and drink and refined grains should be the smallest part of one’s diet. These recommendations, which are part of DGAC’s 2015 report, contain hard limits on only three nutrients: saturated fats, added sugars and dietary sodium.
Just as important is a consideration of what should replace them. Hu and his colleagues on the DGAC recommend replacing saturated fat with sources of unsaturated fat like seafood, nuts, seeds and olive oil.
We Already Knew That Trans Fats Are Bad
Analyses like the one published in BMJ are almost passé when it comes to cutting edge nutritional advice.
"I don’t know how this stuff keeps getting published,” said Christopher Gardner, a nutrition scientist at Stanford University.
For one thing, the dangers of trans fat are already well known. In order to reduce coronary heart disease and fatal heart attacks in the U.S., the FDA announced last June that they are requiring food manufacturers to significantly reduce trans fat levels in foods within the next three years. The trans fat reduction will mostly affect companies that make highly processed foods like cookies, frozen pies, fast food, frozen pizza, ready-to-use frosting and refrigerated biscuit and cinnamon roll doughs.
We're Asking The Wrong Questions
Focusing dietary advice on nutrients like saturated fat rather than real foods is a surefire way to make different versions of the same mistakes, according to Gardner.
“Just focusing on one nutrient at a time is America’s way of oversimplifying and trying to game the system,” explained Gardner.
In the 1980s, scientists told the public to steer clear of the saturated fat and cholesterol in meat and dairy foods, which prompted Americans to fill up on cereals and refined grains. The focus on nutrients also gave processed food companies a way to manipulate their products to be more appetizing while claiming that their snacks were “fat free." Since then, Americans have gotten heavier -- and rates of chronic disease like diabetes have doubled since 1988.
“Nutrients allow the packaged processed food folks to say, ‘Ah! Let’s take our chip, let’s take our cookie, let’s take our breakfast cereal and remove that one nutrient that folks are interested in. Now we have a health food!’” said Gardner. "But we don’t. We still have junky cookies and chips and breakfast cereals that are mostly sugar and artificial things, because they just removed the trans fat, or they just removed the saturated fat.
Charles Mueller, an associate professor of clinical nutrition at New York University, agreed. While he praised the BMJ study for its sound methodology, he said that studies that focus on specific nutrients could be confusing to the general public.
"They are informative, but they are misleading,” said Mueller. The reason? Whole foods are so much more than the sum of their nutrient parts. For example, there are so many reasons that broccoli is good for us. Boiling down the vegetable's effect on our health by reducing it to its fiber or its minerals or its complex carbohydrate status would be to miss the totality of the food itself. There are many studies that talk about food rather than the nutrients, Mueller pointed out, and these are the research papers Americans should be more focused on.
"Nutrients do not equal food,” said Mueller. "We shouldn't be telling people what nutrients to eat, we should be telling people what kind of food to eat."
Thankfully, there are signs that Americans are starting to get the message about eating whole, real foods, as opposed to obsessing over one nutrient. For instance, Americans are drinking way less soda than ever before, and consumers are telling food companies that they are willing to pay more for fresh, whole foods that can prevent disease.
The bottom line? Don’t pay too much attention to studies that zoom in on singular nutrients and their effect on human health. Like the one published in the BMJ, focusing on one or two nutrients while not accounting for the effect whole foods have on health don’t have much more to offer us in 2015.