Not everyone will experience the full range of symptoms, but lactose intolerance often causes bloating, discomfort, and stomach pain. And if you look outside the U. Of course, there are lactose-free milk products available, and the USDA has now expanded their dairy recommendations to include fortified soy products.
Fortified plant milks are optional, says Ludwig and Susan Levin, the director of nutrition education for the Physicians Committee for Responsible Medicine PCRM , an organization that advocates for plant-based diets and animal rights. Some studies indicate that dairy consumption, including whole milk , is closely linked with rates of prostate cancer, as Willett and Ludwig noted in their review. Dairy consumption was also associated with endometrial cancer, especially in older women not receiving post-menopause hormone therapy.
Much of the concern around milk revolves around the growth hormones it contains, most of which occur naturally because it comes from a lactating female cow. And one possibility is that it could increase the risk for cancer. Even less definitive is the much-debated link between cow's milk and breast cancer, as well as other cancers.
Research has been mixed, and the quality of studies that deal with life-threatening, long-term diseases like cancer are often limited by the time constraints of traditional studies. According to the review from Ludwig and Willett, studies connecting low-fat milk with reduced blood pressure have been inconsistent, and neither whole or low-fat milk has been clearly linked to heart disease or stroke.
Willett says drinking three glasses of full-fat milk a day would probably add too much saturated fat to a diet. But he says three glasses of any type of milk is probably too much in the first place.
For instance, drinking low-fat milk might actually leave children feeling less full at mealtime, causing them to compensate with more of other foods. He says more research is needed to draw conclusions between milks of varying fat levels and any potential role they play in heart or blood pressure issues. Because health and health disparities are closely linked to race in the U.
The fact is that mother's milk contains nutrients that benefit animals other than that mother's babies — and it would be unnatural for those other animals to ignore that discovery. Is Drinking Milk Unhealthy? Just about anything can be consumed in quantities or contexts that make it harmful. But are dairy products bad for you when they are consumed in the context of a balanced and nutritious diet? Do they cause heart disease, cancer, or other diseases?
Diane specifically mentioned a correlation between dairy consumption and osteoporosis. But just because two things occur simultaneously does not mean that one thing causes the other. In this case, there are several more likely explanations for why these populations might have higher rates of osteoporosis, including genetics, activity levels, and other aspects of diet and lifestyle.
When we compare people within these populations instead of across them , milk and dairy consumption are associated with better bone health — which makes sense, because milk is an excellent source of absorbable calcium, vitamin D, and other nutrients that help to build strong bones.
Others have claimed that drinking milk causes breast cancer, an argument based mostly on animal or test tube studies and observations gleaned from a single highly unrepresentative population. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Discover World-Changing Science. Fiber 2. In , Harvard University nutritionist Mark Hegsted wanted to find out.
There was, however, a practical complication that prevented him from experimenting on the general population to understand this paradox: After a person cuts back on calcium, it can take months or years for the change to show up in the body.
So Hegsted went looking for a chronically calcium-deprived population. He found one at the Central Penitentiary of Lima, Peru. Inmates locked up in the grim, year-old stone prison subsisted on a rice-and-beans diet that was extremely low in calcium. They typically drank milk once a week. Hegsted got permission from prison officials to monitor the calcium intake of 10 volunteers. Americans kept on drinking their milk and eating their dairy, with plenty of encouragement from the government.
Once called the Food Pyramid, these guidelines have been renamed MyPlate. They determine which agricultural sectors benefit from taxpayer-funded nutrition campaigns and how the billions of dollars in federal food aid flow each year to needy Americans through programs like the Special Supplemental Nutrition Program for Women, Infants, and Children WIC. Since , the dietary guidelines have advised adults to consume the dairy equivalent of three cups of milk per day—a full cup more than was previously recommended.
This winter, the USDA is set to publish new guidelines based on advice from a panel of scientists who have reviewed the latest research—but most experts expect no change in the dairy recommendations. A cup of yogurt has milligrams, and an ounce of Swiss cheese has But outside the dairy family, calcium is harder to come by.
The scientist behind much of the new dairy research is Walter Willett, who leads the nutrition department at Harvard. Willett grew up on a dairy farm and did his graduate work in the s at Harvard under Hegsted. Less clear, however, was the chemical pathway that explained this finding. Milk, which is designed to give young animals everything they need to grow, is a substance of beguiling complexity.
Willett is thin and tall, with hazel eyes and a handlebar mustache. Soft-spoken and serious, he is, at heart, a data nerd. In , he published the results of an eight-year survey focused on calcium consumption by more than 43, men.
A decade later, a roundup of all the available research—by then, eight epidemiological studies and five randomized, controlled trials— determined that calcium intake does not significantly decrease the risk of hip fracture in women or men.
Last year, another sweeping study came to the same conclusion—in fact, it found that women who drank two and a half or more glasses of milk a day had a higher fracture risk than their counterparts who drank less than one glass a day.
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