Is Milk Bad for You? Health Benefits and Side Effects

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Milk contains essential vitamins and minerals and offers several health benefits as part of a nutritious diet. Humans have been drinking cow’s milk throughout history, with studies tracing consumption back to the Middle Neolithic period, about 6,000 years ago. But drinking milk may also have harmful effects for some people.

Cow’s milk is not ideal for everyone. This article explains the pros and cons of dairy in your diet and who should stick to dairy-free alternatives.    

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Milk Nutrition Facts

Milk is rich in protein and contains 18 of 22 essential nutrients, so it is often recommended as part of a balanced diet.

The Nutrients in Milk

According to the United States Department of Agriculture (USDA), an 8-ounce glass of reduced-fat (2%) milk contains:

Calories

The amount of calories per serving of milk depends on its fat content. Eight ounces of full-fat milk has 146 calories compared to 83.6 calories in nonfat. Milk is a good energy source.

Carbohydrates

The lactose in milk makes it a rich source of carbohydrates. The body breaks these down into glucose (blood sugar), which it converts into energy. Some dairy products have added sugars, increasing their carb content.

Protein

Milk also contains high levels of protein, making it a good source of this essential nutrient. About 20% of the protein in milk is whey, a soluble protein that the body digests faster. The remaining 80% is casein protein, an insoluble protein. Dairy protein contains all nine essential amino acids, which help with protein, neurotransmitters (brain chemicals), and hormone production.

Fats

Milk is categorized by fat content, so it’s easy to sort out what type will have more or less of this nutrient. Full-fat milk contains 7.8 g per 8-ounce serving, whereas nonfat milk has only trace amounts. About 70% is saturated fat (which can build up in your arteries when consumed in excess), and the rest is unsaturated.

Vitamins and Minerals

Milk is a significant source of several essential vitamins and minerals, including:

Benefits of Milk

There’s a reason you may remember public health campaigns encouraging people to drink milk. Researchers have found that dairy consumption offers numerous health benefits.  

Appetite Control

Studies suggest that milk’s high protein, lactose, and fat content keeps you full for longer and can help with appetite control. In a study of children with obesity from 2018, full-fat milk was found to suppress hunger for up to four hours.

Bone Development

Milk contains many vitamins and minerals necessary for bone formation and growth, including protein, calcium, phosphorous, magnesium, manganese, and zinc, as well as vitamins D and K. In children and adolescents, studies have linked dairy intake with healthier bone development.

High in Protein

Milk is a rich source of protein, containing about 8 g per one cup (8-ounce) serving. This results in several health benefits, including:

  • Bone density: Researchers found that protein interacts with other minerals in milk to preserve bone density as adults age.
  • Healthy teeth: Comprising 80% of dairy’s protein content, casein may protect your teeth, and studies have associated milk consumption in children with fewer cavities.
  • Muscle development: Milk protein can also help build and maintain muscles; researchers found that drinking milk after resistance training spurs anabolism, the process of repairing and building muscle tissues.   

Bone and Dental Health

There’s something to the public health campaigns that connected milk with strong teeth and bones. Research has found that nutrients in milk, including phosphorous, vitamin D, calcium, magnesium, and protein, play a role in bone development for both children and adolescents. Some evidence also indicates that it helps adults in this respect, too.

Milk and Smiles

There’s significant evidence that drinking milk promotes dental health. Milk’s calcium and phosphate content helps teeth retain strength and protects them from cavities.  

Heart Health

The relationship between milk consumption and heart health is complicated, with positive and negative effects. Some studies have consistently connected low-fat, high-calcium dairy products to lower blood pressure. This reduces the risk of hypertension (high blood pressure), protecting the body from heart issues and stroke (a dangerous interruption of blood flow in the brain).

Diabetes Prevention and Management

In several ways, drinking milk can help the body fight diabetes, a chronic inability to effectively metabolize sugar. Studies have found high dairy consumption reduces the chances of developing childhood obesity (excess weight), a significant risk factor for diabetes. Furthermore, researchers have noted that consuming milk on a calorie-restricted diet can help facilitate weight loss, which helps to manage diabetes.

Negative Side Effects of Milk

Though milk drinking can yield many positive health effects, it can also come with potential downsides. Some people are allergic or intolerant to dairy. Dairy consumption has also been linked with certain conditions.

Acne

Acne (acne vulgaris) occurs when hair follicles get plugged up with oil or dead skin, causing pimples or bumps on the skin. In a broad-ranging review of data from over 78,000 children and adults ages 7–30, consuming dairy—drinking milk and eating cheese—increased the chances of breakouts. Researchers aren’t sure why this happens but believe an inflammatory (immune) response to dairy may be to blame.

Other Skin Conditions

High dairy consumption has also been associated with inflammatory skin conditions. In some people, dairy consumption may trigger eczema (itchy, flaky skin) and rosacea (red, flushed skin) attacks. Even in those who don’t have an outright allergy, researchers noted that consumption can cause this response.

Allergies

Researchers estimate that up to 3% of toddlers and infants under 3 have some form of a milk allergy. This declines over time, and 80% of children with milk allergies outgrow them by age 16. These allergies arise as dairy triggers inflammatory responses. An allergic reaction to consuming can cause:

  • Hives or bumps developing on the skin
  • Upset stomach
  • Vomiting and nausea
  • Bloody stool
  • Anaphylaxis (a rare and severe onset systemic shock causing breathing difficulties)

Lactose Intolerance

As many as 68% of people have lactose malabsorption and lactose intolerance. These are problems digesting and breaking down lactose (milk sugar). Lactose intolerance can cause bloating, nausea, diarrhea, gas, abdominal pain, a grumbling stomach, and vomiting.

Bone Fractures

Though milk consumption has been linked with bone development and maintenance, it may also increase the risk of breaking your bones. In a wide-ranging study assessing data from over 100,000 participants, researchers found that increased intake in women between the ages of 39 and 79 led to a higher incidence of bone fracture.

Cancers

The evidence regarding milk consumption and cancers is mixed, with some studies finding it protective against colorectal cancer. In several studies, dairy intake increased prostate cancer risk in men and ovarian cancer in women. Researchers have also connected dairy consumption with increased breast cancer risk, though further studies to confirm this remain necessary.

Heart Disease

Though dairy intake has been associated with reducing high blood pressure and boosting heart health, it may also bring about negative side effects. Full-fat milk can cause spikes in low-density lipoprotein (LDL, or “bad”) cholesterol, which increases heart disease risk. However, studies have yet to consistently link increased dairy consumption with this issue.

How Much Milk Should You Drink a Day?

Barring milk allergy or lactose intolerance, most nutritional guidelines recommend regularly including dairy in your diet. It’s an excellent source of animal fats, calcium, and vitamin D, among other nutrients. According to the USDA, recommended daily amounts are:

  • Three servings (3 cups of milk or yogurt; 3 ounces of cheese) for adults
  • Three servings for children ages 9–18
  • Up to 2.5 servings for toddlers and infants under 2

However, all of this comes with some controversy. Citing potential links to diseases and the disproportionate lactose intolerance among non-White populations, the American Medical Association (AMA) urged the USDA to revise these guidelines and indicate that dairy is optional.

Who Should Avoid Cow’s Milk?

As much as dairy products can be part of a nutritious diet, they aren’t right for everyone. Those who have milk allergies or display symptoms of milk allergies—especially infants and toddlers—should avoid milk. Another reason to avoid dairy products is lactose intolerance. Compared to White people, this issue is more common among African Americans, Native Americans, Asian Americans, and Hispanic Americans.

Talk to a healthcare provider if you or your child is experiencing digestive symptoms or hives after drinking milk. They can determine if you have lactose intolerance or a dairy allergy.

Alternatives to Cow’s Milk 

If cow’s milk isn’t a good option for you, many plant-based alternatives exist. These come from four different sources:

  • Grain milks like oat or rice milk
  • Legume milk, such as soy or pea milk
  • Nut milks like almond, cashew, and coconut milk
  • Seed-based milk, such as hemp or flax milk

However, it’s important to remember that the nutritional content of soy, almond, oat, and other dairy alternatives varies and may not match that of milk. Of all the possible types of milk, only soy milk fortified with calcium, vitamin D, and vitamin A is considered comparable to dairy milk in the USDA’s dietary guidelines.

When choosing alternatives to cow’s milk, check the milk’s nutrition facts label. Look for other options that are high in protein and low in saturated fats and don’t have added sugars or saturated fats. If you’re on a diet, be aware that some plant-based milks have more calories than low-fat or skim milk.     

Summary

Though it isn’t suitable for everyone, milk can be a healthy, nutritious part of your diet. Dairy products are rich in necessary vitamins and minerals and are good sources of protein, offering many health benefits. However, some people are allergic to milk or have lactose intolerance, and consuming milk can lead to specific health problems. Plant-based alternatives, such as soy milk, may not have the same nutritional content as milk. Talk to a healthcare provider about whether to include milk in your diet.

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