Dairy fat: Newfound friend or (still) a foe?

For decades we've believed it's a no-brainer when it comes to choosing lower fat dairy options like skim milk over their full-fat counterparts. And even the most recent dietary guidelines for Americans still emphasizes people choose fat-free or low-fat dairy as part of a healthy eating pattern. Do so and you'll trim your calorie and saturated fat intake but still take in important nutrients like calcium. But studies have emerged which call into question that dairy fat is a health boogeyman. In fact, some data even suggests it could do a body good. So should you be guzzling whole milk and spooning up full-fat yogurt?

Among the studies leading to a pendulum shift in how we view full-fat yogurt and cheese is a 2018 investigation in the American Journal of Clinical Nutrition which found among 2,907 older adults there was no link between blood levels of three fatty acids known to correspond with dairy fat intake and any cause of death, including from heart disease or stroke. In fact, one type of saturated fatty acid -- heptadecanoic acid -- in dairy was associated with lower risk of stroke-related death.

Another study in the journal Circulation discovered those who had higher circulating blood levels of fats associated with dairy intake, on average, had a 46 percent lower risk of developing diabetes over a 15-year period than those with lower levels. More good news for blue cheese lovers: A recent University of Texas study reported that the substitution of 2 percent of daily calorie intake from meat-based saturated fat with calories from dairy-based saturated fat was associated with a 25 percent lower heart disease risk in 5,209 people over a decade.

And despite the extra calories it introduces, the fat in dairy may help, not hurt, in the battle against the bulge. A Harvard observational study of more than 18,000 middle-age women found that a greater intake of high-fat dairy products, but not the consumption of low-fat dairy items, was associated with less risk of weight gain over an 11-year period.

The studies don't answer the question of why eating richer dairy products may be less hazardous than once thought. But there are several theories. "Whole fat dairy contains various types of fat and some are less problematic than others," says Joan Salge Blake, R.D., a clinical associate professor of nutrition at Boston University. For instance, she points out that conjugated linoleic acid, which is greatly reduced in low-fat dairy, may help slow the progression of heart disease. It's also possible that the unique make-up of fats in dairy may be acting directly on cells to improve insulin sensitivity and other health measures.

Some of the negative effects of dairy saturated fat might be neutralized when eaten as part of the complex "food matrix" formed by dairy foods. Whole milk dairy foods are more than vehicles for fat. "Calcium, vitamin D and potassium are three prevalent nutrients in milk that most Americans don't get enough of," notes Salge Blake. Certain dairy foods, like yogurt, kefir and aged cheese, are fermented, meaning they supply beneficial microbes that may help in the battle against certain diseases. And there are those who would argue that if someone is choosing to skip whole-fat dairy in favor of low-fat or fat-free versions that are full of added sugars, they're hardly better off. It is important to study the effect of food as a whole and not just its specific nutrients.

In the battle of the bulge, higher fat dairy may have more immediate calories, but if they boost satiety through slower digestion and improved taste and texture satisfaction in the end overall daily calorie intake might be slashed resulting in slimmer waistlines.

But just because there's evidence against dairy fat being a health villain, it doesn't mean you shouldn't attempt to exercise restraint instead of smearing butter on everything. "People should still follow guidelines of limiting overall saturated fat intake to 10 percent of total calories," advises Salge Blake. And that is hard to do when you drown your cereal in whole milk and reach for a second serving of glistening pizza. Keep in mind that a number of large studies continue to show that replacing some of the saturated fat in a typical American diet from sources like dairy and meat with unsaturated sources is strongly linked to better long-term health. So while full-fat dairy may be compatible with a heart-healthy diet, there are other fatty foods that may contribute more strongly to longevity, such as fish, seeds, nuts and olive oil.

So, how to proceed? The body of data that is starting to show the need for you to drop only lesser fat dairy products in your shopping cart has reached its expiration date. So if you prefer to spoon up full-fat yogurt or nibble on quality aged cheese as part of your recommended three dairy servings a day, go ahead. But only do so with an eye on portions and what else you're eating. "If you're going to include full-fat dairy products in your diet you should balance things out by eating other foods like fish and legumes that are lower in calories and saturated fat," Salge Blake says. Eating too much full fat dairy that comes bundled with sugar, refined carbohydrates, and other saturated fats, as with ice cream, pizza and fast food, is bound to backfire.

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