Dairy: Health food or health risk?

When I was a growing teenager, I drank as much milk as possible (often straight from the carton while standing in front of the open fridge, much to my mother's chagrin). I'd seen the TV ads — milk and other dairy foods were the express ticket to stronger bones and bigger muscles.

But today dairy's nutritional reputation is as clear as, well, a glass of milk. Dairy is either good or bad for you depending on the latest diet trend or recent study. So what is the truth — is dairy healthy, or a health risk? "Dairy isn't necessary in the diet for optimal health, but for many people, it is the easiest way to get the calcium, vitamin D, and protein they need to keep their heart, muscles, and bones healthy and functioning properly," says Vasanti Malik, nutrition research scientist with the Harvard T.H. Chan School of Public Health.

Dairy products as a source of calcium and protein

Dairy products like milk, yogurt, cheese, and cottage cheese, are good sources of calcium, which helps maintain bone density and reduces the risk of fractures. Adults up to age 50 need 1,000 milligrams (mg) of calcium per day. Women older than 50 and men older than 70 need 1,200 mg. (For comparison, a cup of milk has 250 mg to 350 mg of calcium, depending on the brand and whether it's whole, low-fat, or nonfat. A typical serving of yogurt has about 187 mg of calcium.) Milk is also fortified with vitamin D, which bones need to maintain bone mass.

Older adults also need protein to protect against sarcopenia, the natural age-related loss of muscle mass and strength, and dairy can be a decent source. The recommended amount for older adults is 0.8 grams per kilogram of body weight. A 180-pound man would need about 65 grams of protein per day, and a 140-pound woman would need about 50 grams.

Still, when it comes to the direct health impact of dairy, the existing science is mixed. Some research warns against consuming too much dairy, while other studies show some benefits from regular dairy consumption.

Is one form of dairy better than another?

The American Heart Association still recommends adults stick to fat-free or low-fat dairy products. But new research suggests full-fat dairy might not be much of a threat to heart health. A report presented at the 2018 Congress of the European Society of Cardiology looked at 20 studies involving almost 25,000 people, and found no association between the consumption of most dairy products and cardiovascular disease. The exception was milk, but the results showed that only very high milk consumption — an average of almost a liter a day — was linked with a higher risk of cardiovascular disease.

Some science has even suggested that the right kind of dairy may prevent heart disease. A study involving 2,000 men published by the British Journal of Nutrition found that those who ate plenty of fermented dairy products like yogurt and cheese had a smaller risk of coronary artery disease than men who ate less of these products. This supports earlier studies that showed that fermented dairy products have more healthful effects on blood lipid profiles and the risk of heart disease than other dairy products.

Another proposed benefit, however, has not panned out. "Despite the push by the US dairy industry to promote dairy products, especially milk, as a weight-loss tool, research hasn't supported that except when also restricting calories," says Malik.

The bottom line

When it comes to overall health benefits, it seems that dairy is neither a hero nor a villain. Adding some dairy to your daily diet — a splash of milk in your coffee or a cup poured over your breakfast cereal, or a slice of cheese on a sandwich — can help you get some of the vital nutrients you need. "But keep in mind that eating a well-balanced diet that includes plenty of green leafy vegetables and nuts can better help you get the calcium and protein you need rather than relying too much on dairy," says Malik.

Malik still prefers most people stick with low-fat dairy, as this helps reduce your intake of saturated fat but still offers good amounts of nutrients. Alternatively, you can choose almond and soy milk substitutes — but be aware that they have lower amounts of protein than regular milk. For a single go-to dairy source, Malik recommends plain Greek yogurt. (Avoid flavored versions, which are high in sugar). "It has more protein than regular yogurt and contains probiotics that help with gut health. And it's quite versatile, as you can eat it alone or add it to other dishes like smoothies and use it as a substitute for cream in recipes."