Cow’s milk, a drink people often associate with good health, is one of the most popular beverages in the United States and Europe.
Milk is a natural food source for mammals. Animals, including humans, produce milk to feed their young until they are ready for solid food.
Research about milk is conflicting, however, with different studies claiming milk is either good or bad for the body.
This article looks at the potential health benefits of cow’s milk and discusses alternatives.
Official sources, such as the Dietary Guidelines for Americans 2015–2020, recommend that adults eat about 3 cup-equivalent of low fat or fat-free dairy each day as part of a healthful diet.
This amount can include milk, yogurt, cheese, and fortified soy beverages.
The following sections look at the possible benefits of milk for human health.
Calcium is an essential nutrient for strong bones and teeth, muscle movement, and nerve signals. Health authorities recommend getting enough calcium to help prevent bone fractures and osteoporosis.
Milk offers a rich source of calcium. Manufacturers fortify cow’s milk with vitamin D, another nutrient that benefits bone health.
While calcium is important, not all studies agree that milk is good for preventing osteoporosis or fractures, as a 2019 review discusses. Due to this discrepancy, scientists still need to do more research.
Milk is a source of potassium, which can help the blood vessels dilate and reduce blood pressure.
Getting more potassium while also reducing sodium (salt) intake can lower blood pressure, reducing the risk of heart disease and stroke.
Many people in the U.S. do not get their recommended daily requirement for potassium of 3,400 milligrams (mg) in males and 2,600 mg for females.
Other potassium-rich foods besides milk include:
Cow’s milk also contains a high amount of saturated fat and cholesterol, which can increase the risk of heart disease, so people should eat dairy in moderation.
Milk contains calcium and vitamin D, two nutrients that may help protect against cancer.
Vitamin D might play a role in cell growth regulation. It may help protect against colon cancer, and possibly prostate and breast cancer. However, research has also linked high vitamin D levels to an increased risk of pancreatic cancer.
Many factors affect cancer risk. Likewise, cancer can take a long time to develop, so it is difficult to study its causes and risk factors.
Scientists still need more long-term research to establish the facts with any certainty.
Manufacturers often fortify cow’s milk and plant milk with vitamin D.
Cow’s milk helps baby cows grow fast, so it makes sense that cow’s milk can aid muscle growth. Cow’s milk is a rich source of high quality protein, containing all essential amino acids.
Whole milk is also a rich source of energy in the form of saturated fat, which can prevent muscle mass from being used for energy.
Low fat milk can provide the benefits of milk while supplying less fat.
Osteoarthritis of the knee currently has no cure, but researchers say they have linked drinking milk every day to reduced progression of the disease.
Their research appeared in the American College of Rheumatology journal Arthritis Care & Research.
According to the Dietary Guidelines for Americans 2015–2020, the dairy group includes cow’s milk and soy milk. The group contains the following key nutrients:
- vitamin A
- vitamin D (in fortified products)
- vitamin B-12
The nutritional breakdown of milk depends on the fat content.
A 100-gram (g) serving of whole milk with 3.25% fat contains:
- 61 calories
- 4.8 g of carbohydrate
- 3.25 g of fat
- 3.15 g of protein
A 100-g serving of low fat milk contains:
- 43 calories
- 4.97 g of carbohydrates
- 0.97 g of fat
- 3.48 g of protein
A 100-g serving of soy milk contains:
- 33 calories
- 1.67 g of carbohydrates
- 1.67 g of fat
- 2.92 g of protein
Some important nutrients that all milk provides include:
Dairy products, including milk, are among the richest dietary sources of calcium. Calcium is essential for bone and tooth health, blood clotting, and blood pressure.
Pair calcium-rich foods with sources of magnesium and vitamin D, as vitamin D supports calcium absorption in the small intestine, and magnesium helps the body incorporate calcium into the bones.
Choline is an important nutrient for sleep, muscle movement, learning, and memory. It also helps with nerve signals, fat absorption, and inflammation.
Potassium is vital for heart health, which includes reducing the risk of stroke, heart disease, and high blood pressure.
A 100-g serving of cow’s milk contains around 162 mg of potassium, slightly more than in many soy milk beverages.
In the case of lactose intolerance, however, a symptom such as diarrhea can lead to potassium depletion.
Fortified vitamins and minerals
Manufacturers fortify most milk, including cow’s, soy, almond, and others, with additional vitamins and minerals that are not present naturally. These added nutrients include vitamin A, riboflavin, vitamin B-12, and pyridoxine.
Exposure to light destroys some vitamins, especially A and riboflavin, so milk that people store in transparent containers will have lower nutrient levels.
The following sections look at the possible adverse health effects of drinking milk.
Dairy is high in saturated fats. The American Heart Association (AHA) point out that eating too many saturated fats can increase cholesterol levels, raising the risk of heart disease and stroke.
The AHA recommend that people get no more than 5–6% of their total calories from saturated fats.
Lactose intolerance is a condition where the body does not produce lactase, an enzyme it needs to break down a sugar called lactose that occurs in milk.
A milk allergy, or hypersensitivity, is different from lactose intolerance. In an allergy, the body reacts to the proteins, not the sugars, in milk.
A cow’s milk allergy can cause symptoms, such as wheezing and asthma, diarrhea, vomiting, and gastrointestinal distress. Severe allergies can lead to anaphylaxis, a life threatening allergic reaction.
Too much potassium or phosphorous
Getting too much of certain nutrients can be harmful. Overconsumption from diet alone is rare, but certain medications or medical conditions can make it more likely.
If a person has kidney problems, too much potassium or phosphorous can be harmful. Too much potassium is known as hyperkalemia.
Too much calcium
Too much calcium, or hypercalcemia, can cause constipation, kidney stones, or kidney failure. It is rare for this to happen from diet alone, but it can be a risk when a person is taking calcium supplements.
Hormones and antibiotics
Cow’s milk may contain residues of hormones and antibiotics, as well as dioxins and polychlorinated biphenyls (PCBs).
These residue substances can have a negative impact on human health, including adverse effects on the nervous system, reproductive system, and immune system. They may potentially raise the risk of certain types of cancer.
While calcium and vitamin D from cow’s milk can benefit bone health, there is also some evidence that animal proteins in the diet, for example, from cow’s milk, have an acidifying effect.
According to Harvard researchers, this could harm bone health by causing the body to pull calcium from the bones to restore optimal blood pH levels. Not all agree with this, however.
As such, the net benefit of calcium in cow’s milk may be lower than expected.
The Centers for Disease Control and Protection (CDC) say that infants should not drink cow’s milk before 12 months of age. This is because cow’s milk has too many proteins and minerals for an infant’s kidneys to handle and may put them at risk of intestinal bleeding.
Anyone who has an allergy or intolerance to cow’s milk, or who is considering avoiding cow’s milk for ethical or environmental reasons, can try milk alternatives.
According to the Dietary Guidelines for Americans, soy beverages fortified with calcium, vitamin A and vitamin D are part of the dairy food group as they have similar nutritional composition to milk.
Other milk alternatives made from plants may contain calcium but are not part of the dairy group as their nutritional profile is not similar to soy milk or cow’s milk.
Cow’s milk is a good source of calcium, protein, and other important nutrients that can have benefits for health.
According to one Harvard researcher, however, dairy is not necessary for optimal health. Many others recommend it, though, and many people find cow’s milk an easy way to get essential nutrients, including calcium, vitamin D, and protein.