If you lived your life simply by following the health headlines, you may have switched from skim milk to whole-fat milk and back again -- in the span of two days.
A study published in the Annals of Internal Medicine on Monday found that those who ate the most high-fat dairy products, like whole milk, butter, and cheddar cheese, had about a 60 percent lower risk of developing adult-onset diabetes over 14 years than those who opted for skim milk and fat-free yogurt. On the flip side, a study out today in the Journal of the American Dietetic Association suggests that seniors over 70 who eat a low-fat diet with lots of fruits and vegetables have a 40 percent lower risk of dying within the next 10 years than those who eat the most whole milk, butter, and cheddar cheese.
Death or diabetes? Not a great choice since diabetes also increases your risk of dying years ahead of those who don't have the condition, not to mention increasing your risk of heart, vision, and kidney problems. To me, these two studies basically tell us that there's a whole heck of a lot that nutrition researchers don't know when it comes to dietary fat.
"The bottom line is that we shouldn't change our dietary habits based on one study," says Dr. Dariush Mozaffarian, an asssociate professor of medicine at Brigham and Women's Hospital. He led the study linking high-fat dairy foods to lower diabetes risk and says most of the diabetics he sees are utterly confused when it comes to fat.
"I ask them what they're eating, and they tell me Corn Flakes with skim milk, rice, white bread and turkey, and potatoes." he says. "It's mostly carbohydrates, little protein, and almost no fat."
That's bad, very bad for their blood sugar levels. Adequate amounts of fat are necessary, he explains, to slow digestion, increase satiety, and prevent dangerous spikes in glucose that can cause complications with the heart, kidneys, eyes, and nervous system.
Many of Mozaffarian's patients don't realize that there are good fats -- olive oil, nuts, avocados rich in monounsaturated fats -- and bad fats -- trans fats found in hydrogenated oils and saturated fats found in red meat and egg yolks.
The fats he looked at in his study, called trans-palmitoleic acid, appear to have beneficial effects in the body, but no one knows for certain since they haven't been well studied. What's more, whole milk dairy foods are also high in saturated fat, which is known to raise "bad" LDL cholesterol levels. So whether the fat content in, say, whole milk is a net positive or a net negative remains murky, which probably explains the conflicting studies.
At this point, Mozaffarrian says, it's too early to know whether it's wise to choose full-fat dairy foods over the low-fat versions. Your best bet then is to aim to get two to three servings a day of dairy foods, and if you like the taste of whole-milk cheddar over fat-free American cheese, go for it!
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