Got (enough) milk?

The dairy industry has been telling us for decades that cow’s milk is essential for healthy bones and helping children grow. It’s also a message backed by the federal government, which says that eating or drinking dairy is important for building and maintaining strong bones. But is cow’s milk really essential to a child’s growth? Should adults be drinking it for stronger bones too? How much milk and calcium do our bodies really need?

We spoke with experts about the role of dairy in bone growth and overall health. They agree that plain milk is a far more nutritional beverage than many flavored drinks offered to children. But experts say dairy milk isn’t as essential to overall health as many people believe. For adults or children who don’t like milk or have an intolerance, removing dairy from a healthy and varied diet is unlikely to cause any health issues.

How much calcium do we really need?

If you eat a healthy and varied diet, then you’re likely getting calcium from many foods, not just milk. Calcium can be found in beans, vegetables, whole grains, fish, nuts, seeds, tofu, fortified plant and soy milks, along with cheese and other dairy products.

Various health organizations make vastly different recommendations for how much calcium we need. In the United States, the Department of Agriculture recommends calcium intake of between 1,000 and 1,300 milligrams a day for most of the population, and two to three cups of dairy a day for most children and adults. But the World Health Organization says you only need 500 mg of calcium daily. One cup of cow’s milk contains about 300 mg of calcium.

In general, clinical trials have found that assigning adults to take calcium supplements does not reduce their likelihood of suffering bone fractures. At the same time, studies show that countries with the highest intakes of milk and calcium — like Sweden, Denmark and other countries in northern Europe — paradoxically have the highest rates of hip fractures.

Calcium intake is needed for bone growth and bone mineral density. But studies suggest that the threshold is not as high as traditionally thought. In one randomized controlled trial, researchers recruited boys and girls between the ages of 8 and 16, some of whom were given three servings of milk or dairy every day for 18 months. The study found the extra dairy and calcium intake had no impact on the children’s bone mineral density.

If you don’t want to consume milk or dairy, you can load up on beans, leafy greens, fortified plant milks and other foods high in calcium. If you’re worried about calcium, Walter Willett, a professor of epidemiology and nutrition at Harvard’s T.H. Chan School of Public Health, recommends taking a calcium supplement that contains vitamin D. The dose he recommends is 500 mg of calcium with around 600 IU of vitamin D. “If someone has a good diet, then they probably don’t need a supplement,” Willett said.

How much milk should children be drinking?

In 2019, four leading health organizations — the Academy of Nutrition and Dietetics, American Academy of Pediatric Dentistry, American Academy of Pediatrics, and American Heart Association — came together to publish a consensus recommendation stating that plain water and plain, pasteurized milk are the best two beverages for children 5 and younger, but recommended amounts vary by age.

■ 12 months or younger: No cow’s milk. Up to one cup of water a day.

■ Ages 1 to 2 years: Two to three cups a day of whole milk. One to four cups of water daily.

■ Ages 2 to 3 years: Up to two cups a day of skim (fat-free) or low-fat (1 percent) milk. One to four cups of water daily.

■ Ages 4 to 5 years: Up to 2.5 cups a day of skim (fat-free) or low-fat (1 percent) milk. Up to five cups of water daily.

Willett emphasized that milk is a “complete food” that can provide a lot of nutrients, especially for people who have poor diets. “A lot of people around the world are consuming diets that are 70 to 80 percent starchy staples like rice or corn, and in that situation milk can fill a lot of nutritional gaps,” he said. “But that’s not an optimal diet.”

Does milk make you taller?

In a 1976 British study, 581 elementary-school children living in a low-income area were randomly assigned to receive either school lunch with milk or lunch without milk. After 21 months, the children who got free milk had grown, on average, just 1/10 of an inch taller. The effect was so small, experts say it’s not a clinically meaningful difference for most kids.

“The effect appears to be more pronounced when there’s very deficient nutrition than in other settings,” says Jorge E. Chavarro, a physician and professor of nutrition and epidemiology at the T.H. Chan School of Public Health. If you’re growing well already, “it’s not going to make you super tall.”

Drinking cow’s milk increases your levels of hormones like IGF-1, which promotes the growth of bone and muscle tissue, Willett said.

But Willett, who grew up on a dairy farm in the Midwest, said that any extra growth that may be gained with heavy milk consumption is a double-edged sword. Longer bones are more likely to break, which might explain the higher fracture rates in milk-drinking countries.

Should we be concerned about hormones in milk?

Cow’s milk naturally contains a lot of anabolic hormones for the benefit of newborn calves. “You want calves to be able to get up and run within hours, so there’s all these growth hormones in milk,” Willett said.

Commercial cow’s milk contains sex hormones such as progestin and estrogen because cows on factory farms are pregnant for most of the time they’re milked. Some evidence suggests that these hormones could stimulate the growth of cancers: Large observational studies have linked milk and dairy intake to higher rates of breast, prostate and testicular cancers.

But these studies show only correlations, not cause and effect. Other studies have cast some doubt on these findings, and at the same time many observational studies have found that milk and dairy consumption lowers your risk of developing colorectal cancer. Some researchers speculate that the calcium in dairy has a protective effect on the large intestine.

What if a child doesn’t like milk or can’t tolerate it?

The consensus statement does not recommend plantbased milks for children 5 and under because they are “not nutritionally equivalent to cow’s milk” and may contain added sugars. For children who are lactose intolerant or allergic to milk, or whose families are eating a plantbased diet or avoiding milk for any other reason such as environmental impacts, many experts recommend fortified soy milk, which is considered the most comparable nutritionally.

In a review article, Willett and Harvard physician David Ludwig concluded that “normal growth and development can be obtained throughout childhood without dairy products if attention is given to diet quality, including the use of supplemental B12 in diets that include few animal products and vitamin D to compensate for low sun exposure.”