What's the deal with dairy and heart health?

A Heart Letter reader asked about a short piece in our December 2021 issue, which noted that full-fat dairy products may be less harmful to heart health than experts have assumed. How does that square with advice from nutritionists and the American Heart Association, who have long recommended low-fat or fat-free dairy products? "I'd appreciate a 'thumbs up' or 'thumbs down' on dairy fat," he wrote.

As is true for most dietary advice, the answer isn't a simple yes or no; rather, it depends on a host of factors. These include the amount and source of the dairy fat (which could be butter, cheese, or Greek yogurt, for instance) and perhaps most importantly, what you would eat instead of dairy fat, along with the overall quality of your entire diet. The latest research suggests that either full-fat or low-fat dairy can be included in heart-healthy dietary patterns (see "Dairy and heart disease: What's the link?")

Dairy decisions

"I think that full-fat dairy in moderation can be part of a healthy diet," says Dr. JoAnn Manson, professor of medicine at Harvard Medical School and chief of preventive medicine at Brigham and Women's Hospital. Milk, yogurt, and cheese all count toward the three daily servings of dairy products that federal guidelines recommend. Calcium, one of the key nutrients in dairy products, is important for controlling blood pressure as well as maintaining healthy bones. Note that butter and cream aren't classified as dairy products in the federal dietary guidelines, even though they're made from milk, because they contain little or no calcium. However, soy milk and soy yogurt are classified with dairy products because they're fortified with calcium as well as vitamin D. (The latter is also added to traditional dairy products.)

The low-fat rationale

What's the reason behind the low-fat or fat-free dairy advice? Cow's milk and related products contain saturated fat, and too much saturated fat in the diet can boost blood levels of LDL (bad) cholesterol and, in turn, heart disease risk.

But there's no need to completely avoid saturated fat. The average recommended limit for the general population is around 18 grams per day. People with heart disease should aim for about half that limit, or about 9 to 10 grams per day. Because one serving of full-fat dairy has about 5 grams of saturated fat, most people could certainly consider using whole milk or 2% milk on their morning cereal, if they choose, or snacking on full-fat yogurt — if the rest of their diet has little saturated fat, says Dr. Manson.

Healthier choices

Low-fat dairy products have fewer calories as well as slightly more protein and calcium compared with their full-fat counterparts (see "Dairy decisions: Calories and beyond"). More important, however, is what you eat when you cut back on calories from saturated fat. "Often, people replace those lost calories with sugar and refined carbohydrates, and that does not lead to a lower risk of heart disease," Dr. Manson explains. What may help is replacing dairy and other sources of saturated fat with foods rich in unsaturated fat, such as nuts, avocados, or olive oil.

If you like dairy, enjoy it with other healthy foods. Plain, full-fat yogurt topped with fresh fruit is better than nonfat or low-fat yogurt that comes with added fruit, since that addition comes in the form of sugary jam. Cheese, on the other hand, is often eaten with refined grains and meat — think pizza, burgers, macaroni and cheese, and Mexican food. Instead, have a small piece of cheese with whole-grain crackers or fruit, or sprinkle cheese on a salad.

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