Is Milk Bad for You? Here's What the Science Says

From milk and bone strength to lactose intolerance, explore the ongoing debate whether cow’s milk is bad for you. If dairy isn’t for you, experts discuss alternative plant based milk options.

By Sophie Putka
Oct 27, 2023 2:30 PMMar 25, 2024 5:46 PM
Woman hand in deny, saying no to drinking dairy milk.  Lactose intolerance and dairy problem concept
(Credit: ThiagoSantos/Shutterstock)


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If you grew up in the 1990s and 2000s, you couldn’t turn on the TV or open a magazine without seeing these two words: Got milk? And let’s not forget about the milk mustaches.

Even supermodel Gisele Bündchen donned one in this 2001 ad, posing with a glass of milk in hand, next to floating text that reads: “Want strong bones? Your bones grow until about age 35 and the calcium in milk helps. After that, it helps keep them strong. Which means milk is always in fashion. Got milk?” 

The iconic campaign was created for the California Milk Processor Board and was later licensed to other players in the dairy industry. But times have changed, and the public’s attitude toward milk has soured. 

You’ve surely heard claims that cow's milk is unnatural to drink (especially beyond childhood), or that milk consumption actually does more damage than good. But are any of these true?

“What are the unique nutrients that dairy has that nothing else has? Nothing,” says Christopher Gardner, a professor and nutrition researcher from the Stanford Prevention Research Center. “It is true calcium is easier to get from milk than just about anything else. That is totally true. But you can get calcium from lots of other things.” And while not everyone should rush to dump their dairy, there are risks that come from drinking milk excessively.

Is Milk Good for You?

Milk can be a nutritious and healthy part of your diet, but that depends on various factors, including your dietary preferences, nutritional needs, and any potential allergies or intolerances. Milk, as we’ve heard over and over, is a good source of calcium, as well as protein and other nutrients like vitamin D and potassium. 

Why Do People Say Milk Is Good for You?

The federal government is milk’s main champion. As early as the 1940s, milk was touted as a guaranteed path to strength, health, and happiness. A poster from the Works Progress Administration era, commissioned by the government to promote milk, shows a grinning couple, dressed in white, playing tennis and golf alongside the slogan “Milk: For Health, Good Teeth, Vitality, Endurance, Strong Bones.” 

Dairy is still featured prominently on the government’s “My Plate” guide, in the corner above a circle neatly divided into four food groups. Even today, the U.S. Department of Agriculture (USDA) and the Department of Health and Human Services say in their dietary guidelines that dairy, especially milk, is an essential part of daily meals. Americans are told that drinking three glasses of milk a day is the best way to meet their calcium requirements. But ultimately, it’s a little more complicated than that.

How Much Calcium Is in Milk?

Depending on the type of milk, a 250 milliliter glass of milk can provide approximately 276 to 293 milligrams of calcium or more. 

The nutrition label on the milk container shows the calcium content, as it can vary between brands. Calcium-fortified milk, for example, may contain more calcium than other products.

Does Milk Contain Vitamin D?

Yes, milk is a natural source of vitamin D. Vitamin D content in cow's milk can vary, but it's a natural component of milk, and it's often added to milk during processing to ensure consistent levels. Vitamin D is essential for calcium absorption and plays a crucial role in bone health. 

When you consume milk, you can also benefit from the vitamin D it provides, contributing to your overall nutritional intake. However, the vitamin D content can vary depending on factors such as the type of milk and any fortification that has been applied to it.

Does Milk Make Your Bones Stronger?

The idea that milk makes your bones stronger is a common belief, but it's somewhat more complex than that. Milk and dairy products are excellent sources of calcium and vitamin D, which are essential for bone health. But they are not the only sources. 

Does Drinking Milk Make You Taller?

Evidence shows that drinking milk does increase height in children. After all, dairy milk is designed to help baby cows grow rapidly, says David Ludwig, an endocrinologist at Harvard T.H. Chan School of Public Health. “Its evolutionary purpose is to drive fast growth in grazing animals that are at risk for predation,” he says. “So if you were a buffalo on the grasslands, a baby buffalo, you'd want to grow as fast as possible so as to not be eaten by a lion.” 

Is Milk Good for Diabetics?

The relationship between milk consumption and diabetes, particularly type 2 diabetes mellitus (T2DM), is a subject of ongoing research and debate. A 2019 review of the potential role of milk proteins shows that increased dairy consumption has been associated with a lower risk of T2DM.

Is Milk Good for a Sore Throat?

Milk can be beneficial for a sore throat for some individuals. While there's a common belief that milk may increase mucus production and worsen a sore throat, the relationship between milk and mucus production is not well-supported by scientific evidence.

In a 2005 study involving individuals with a common cold, milk intake was not associated with increased nasal secretions or worsening of cold symptoms such as cough, nose symptoms, or congestion. 

Does Milk Reduce Heart Disease and High Blood Pressure?

When it comes to the actual cardiovascular benefits or risks of milk products, the research isn’t so clear-cut. U.S. dietary recommendations promote choosing reduced- or low-fat milk products over full-fat varieties, which contain more saturated fat and sodium — both risk factors for heart disease and other problems.

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.

Read More: Everything You Need to Know About Vitamin D

Is Milk Bad For You?

Milk can be a valuable source of essential nutrients for those who can tolerate it and have no dietary restrictions or allergies. However, it's important to consider your individual health and dietary needs when deciding whether milk is suitable for you.

Does Milk Strip Bones of Calcium?

Research on the topic of milk stripping bones of calcium has yielded mixed results. Some studies have found a positive association between milk consumption and bone health, while others have suggested that excessive milk consumption may have negative effects.

According to a 2018 Osteoporosis study of 70-year-old men and women, the consumption of dairy products, including milk, did not appear to have a detrimental effect on bone health.

Does Milk Cause Bone Fractures?

Some medical experts claim excessive milk consumption can lead to bone fractures. According to a 2020 review from Ludwig and Harvard University endocrinologist Walter Willett in the New England Journal of Medicine, countries that tend to consume the highest amounts of milk and calcium also have the highest rates of hip fractures. 

While milk might help kids get taller, those longer bones are more likely to break and are at risk for fractures, Ludwig added. “And tall stature is one of the greatest risks for bone fractures. The bigger they come, the harder they fall," he says. 

This doesn’t necessarily mean that the milk caused their fractures, but if low-dairy populations do not suffer from high rates of fracture, it could mean milk consumption is to blame.

The researchers concluded that while milk contains essential nutrients for humans, those nutrients can all be found elsewhere. In their work, they also opposed the government recommendation — three servings a day of milk and other dairy products — which they say is too high. Milk also might not seem like an essential part of diets if rates of lactose intolerance are considered.

Does Milk Make You Fat?

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. Ludwig also says that it’s important to consider what else is being consumed with milk. For instance, drinking low-fat milk might actually leave children feeling less full at mealtime, causing them to compensate with more of other foods. 

“Instead of the traditional glass of milk and one or two cookies that kids might have eaten in the 60s, now they drink the fat-free milk — which may be a sweetened variety like chocolate or strawberry milk — with four or five cookies to go along with it,” he says. “That's a potentially very bad trade-off for body weight, for cardiovascular disease risk factors, and for chronic disease.” 

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.

Read More: How Much Protein Do You Actually Need in Your Diet?

Does Milk Cause Cancer?

The relationship between dairy consumption and cancer risk is a topic of ongoing research, and findings can vary based on the type of cancer and the specific compounds in dairy products. 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. 

“Cancers are a disease of abnormal growth,” says Ludwig. “But the consequences of that growth-stimulating effect with long-term consumption [of milk] in humans is unclear. And one possibility is that it could increase the risk for cancer.” 

He emphasized that the link is not clearly proven and highlighted the need for more research. 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. 

  • Breast Cancer

Some studies suggest that the hormones and compounds found in dairy products, such as estrogens and insulin-like growth factor-1 (IGF-1), may increase the risk of breast cancer. In a  review published in the International Journal for Disease Reversal and Prevention, higher intakes of cow's milk were associated with a 50 percent increased risk for breast cancer. However, it's important to note that research on this topic can yield mixed results, and study limitations may play a role.

  • Prostate Cancer

The review also indicated that dairy consumption might be linked to an increased risk of prostate cancer. For example, the Physicians' Health Study found that men consuming 2.5 servings of dairy daily had a 34 percent higher risk of developing prostate cancer. Whole milk intake was associated with a risk of progression to fatal disease after diagnosis.

  • Ovarian Cancer

Lactose in cow's milk may be associated with ovarian cancer risk, as it can break down into galactose, which may interfere with hormones that regulate ovarian function. Studies suggest that high milk consumption may increase the risk of serous ovarian cancer.

  • Colorectal Cancer

There may be evidence regarding the relationship between dairy intake and colorectal cancer risk is mixed and inconsistent. This suggests that the link between dairy consumption and colorectal cancer is not well-established.

Read More: What Do Scientists Know About Vitamin D and Cancer?

What Is the Healthiest Milk?

When it comes to the healthiest milk, it’s important to consider the dietary restrictions you may have and the context of your diet. As Gardner puts it, “people don't just drink dairy alone. They drink dairy instead of something, or with something. They eat cheese instead of something, with something.”

For example, while someone who replaces sugary drinks with milk might be making a healthy choice, another person who already has a balanced, nutrient-rich diet and adds milk to it may not experience any added benefit. That’s why plant-based milks, much like dairy milk, are optional.

What Is Plant-Based Milk?

Plant milk is a non-dairy milk alternative made from various plant sources. It is often used as a substitute for traditional cow's milk by individuals who are lactose intolerant, vegan, or prefer plant-based options. 

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, say fortified plant milks are an option. Because their contents can vary, it’s important to check them for added sugars and nutrition content. 

What Are Examples of Plant Milk?

Some experts say other sources of calcium and protein that aren’t milk are equally acceptable to cow’s milk, such as the following:

  • Almond Milk

  • Soy Milk

  • Oat Milk

  • Coconut Milk

  • Rice Milk

  • Hemp Milk

  • Cashew Milk

Do Other Foods Have Calcium Besides Milk?

Milk is not the only food source we can get calcium from. Dietary calcium can come from leafy greens, soy, and other foods, “if you wanted to switch to plant milk … you'd be better eating the almonds than the almond milk, you'd be better eating the cashews than the cashew milk. 

But people are buying this to pour on their cereal, because they grew up putting a white thing on a breakfast grain,” Gardner says. In other words, humans enjoy nutrients that come in some forms more than others, and are not necessarily concerned with what will give them their daily allotment.

And though experts like Levin and Willett note that nutrients in plant-based milks, like calcium, are often comparable to those in dairy milk, there’s nothing special about milk beverages in general. Harvard’s Nutrition Source recommends calcium sources such as fortified orange juice, winter squash, edamame, tofu, and leafy greens.

Read More: People Went Crazy for Almond Milk in the Middle Ages

Is Lactose Intolerance an Allergy?

Lactose intolerance is not an allergy, it is a digestive disorder characterized by the body's inability to fully digest lactose, a sugar found in milk and dairy products. Not everyone will experience the full range of symptoms, but lactose intolerance often causes bloating, discomfort, and stomach pain. 

How Many People Are Lactose Intolerant?

According to a 2017 estimate, approximately 36 percent of Americans can’t digest lactose, a sugar found in dairy products. And if you look outside the U.S., rates of lactose intolerance are even higher. 

Is Lactose Intolerance Genetic?

Up to 65 percent of the world’s population is unable to digest lactose, largely because their ancestors didn’t evolve the genes that allow them to digest it into their adult years. “[Milk and dairy] is pretty much a Northern European tradition,” says Willett. “There are some nomadic [people] like Mongolian or Maasai that do drink milk, but most of the world's population does not consume milk after infancy.” 

What Is Lactose-Free Milk?

Lactose-free milk is a dairy milk product that has had lactose removed. The U.S. Department of Agriculture has now expanded its dairy recommendations to include fortified soy products. 

Read More: Lactose Intolerance Impacts Millions in the U.S.

This article was originally published on Jan. 26, 2021, and has since been updated with new information from the Discover staff.

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