Is butter back? Not if you want to eat to beat diabetes. Even a modest extra daily serving of butter, which is rich in saturated fat, is linked to increased risk of developing type 2 diabetes in middle-aged and older men and women at high cardiovascular risk, according to new research.

But whole-fat milk and full-fat yogurt, also rich in saturated fat, are a whole other story.

Background: How saturated fat affects the risk of developing type 2 diabetes is hotly debated. One reason for different results from research studies is that many kinds of food supply saturated fat in our diets, including dairy products, meats, processed meats and eggs. Each may affect risk differently. Even foods within the dairy food group may have different effects on risk. The new research set out to untangle the confusion.

Study: Over more than four years, 3,349 people, working with nutritionists, tracked their diets. The men were 55 to 80 years old…the women 60 to 80 years old. None had type 2 diabetes at the beginning of the study, although many had risk factors such as smoking, obesity, an unhealthy cholesterol profile or a family history of cardiovascular disease. Each year, their diets were reassessed and their blood sugar levels were carefully tested to see if they had developed diabetes. Over the course of the study, 266 did develop the disease. The researchers adjusted for caloric intake so they could focus just on the effects of different sources of saturated fat on diabetes risk.

Findings: Participants whose diets had the most saturated fat were twice as likely to develop diabetes as those whose diets had the least saturated fat. But when the researchers broke the risk down by actual food types, the story was more nuanced—and perhaps surprising…

• The more butter and cheese, the more diabetes—for example, for each additional three pats of butter (12 grams) in the daily diet more than doubled diabetes risk. Each additional ounce of cheese (30 grams) raised risk by about one-third.

• But the consumption of whole-fat milk had no effect on diabetes risk. Neither did consuming eggs.

• Red meat and processed meat weren’t associated with increased diabetes risk in this study, either, although the researchers note that other studies have indeed found such a link.

• Whole-fat yogurt was associated with a reduced risk for diabetes. For each four-and-a-half-ounce daily serving of whole-fat yogurt, compared with eating no yogurt, diabetes risk went down 35%. While this study didn’t look at how foods affect risk, the beneficial bacteria in fermented dairy may play a role in diabetes protection.

Surprising finding: The total amount of fat in a diet had no statistical association with diabetes risk. But participants who ate the most animal-based fats, versus those who ate the least, had double the risk for diabetes.

Bottom line: Since this study didn’t cover the diabetes risk associated with calorie intake or body weight, it’s not a carte blanche to eat even “healthy” high-fat foods with abandon. It does suggest healthier choices among high-fat foods, however. To reduce your risk of developing diabetes, go easy on the butter and cheese, and favor plant-based sources of fat such as olive oil and nuts.  You also might want to keep your coffee and tea dairy-free, suggests Bottom Line contributing medical editor Andrew Rubman, ND. Casein, the protein in dairy, neutralizes the beneficial polyphenols in those drinks. But there’s no reason to shy away from whole milk on your oatmeal. And it’s a good idea to swap that low-fat yogurt, especially if it’s full of sugar, for a more filling full-fat version. To learn more, see Bottom Line’s article, “The Truth About Yogurt.”

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