Milk has long been associated with good health and is one of the most consumed beverages throughout the US and Europe. It is thought that the ability to digest the milk sugar lactose beyond infancy first evolved in dairy farming communities in central Europe around 7500 years ago.
Popular sayings and slogans such as "Milk: it does a body good" and "Got Milk?" have brought milk into the mainstream media and further propelled the notion of milk being a healthful choice.
Milk can come from many different species of animal, with cow, sheep, and goat milk being the most popularly consumed. There are also many "milk alternatives" available now, such as soy milk, almond milk, coconut milk, hemp milk and more. Even cow's milk comes in many varieties including flavored varieties like strawberry or chocolate, lactose-free milks, milk with added omega-3s, hormone free or organic milks and reduced fat milk.
This MNT Knowledge Center feature will focus solely on cow's milk and is part of a collection of articles on the health benefits of popular foods. If you have an allergy or intolerance to cow's milk, we have an article covering some of the milk alternatives that you may want to consider.
Nutritional breakdown of milk
One cup of milk is considered one serving. The nutritional breakdown of milk depends on the fat content. Whole milk, with 3.25% fat contains 146 calories, 8 grams of fat, 13 grams of carbohydrate and 8 grams of protein in one cup. One cup of nonfat or skim milk has about 86 calories, 0 grams of fat, 12 grams of carbohydrate and 8 grams of protein.
Some important nutrients that all milk provides are:
Calcium's primary job is the development and maintenance of healthy bones and teeth.
Calcium: Dairy products like milk are the best dietary sources of calcium. Calcium has many functions in the body but its primary job is the development and maintenance of healthy bones and teeth. Calcium is also important for blood clotting and wound healing, maintaining normal blood pressure, and muscle contractions including heartbeat. It is important to try to pair calcium-rich foods with a source of vitamin D, as vitamin D helps the small intestine to absorb calcium. There are 306 milligrams of calcium in one cup of skim milk.
Choline: Milk is also one of the best sources of choline; an important nutrient found that helps with sleep, muscle movement, learning and memory. Choline helps to maintain the structure of cellular membranes, aids in the transmission of nerve impulses, assists in the absorption of fat and reduces chronic inflammation.4
Potassium: High potassium intakes are also associated with a reduced risk of stroke, heart disease, high blood pressure, protection against loss of muscle mass, preservation of bone mineral density and reduction in the formation of kidney stones. A high potassium intake is associated with a 20% decreased risk of dying from all causes.3 The recommended daily intake of potassium for all adults is 4700 mg per day.
Vitamin D (fortified): Vitamin D is important for bone health, aiding in the formation, growth, and repair of bones. Vitamin D also plays an important role in calcium absorption and immune function. Vitamin D deficiency has been associated with osteoporosis, depression, chronic fatigue, muscle pain, PMS, hypertension, and breast and colon cancer.
Milk also provides magnesium, phosphorus, vitamins A, riboflavin, vitamin B-6 and vitamin B-12.
Possible health benefits of consuming milk
Bone Health: Everyone has heard that milk is good for the bones. That is because of its powerful duo of calcium and vitamin D. However, it is equally important to have an overall balanced and healthy diet, as adequate calcium and vitamin D alone are not enough to prevent osteoporosis. Regular physical activity and strength training, along with not smoking and eating a diet low in sodium and high in potassium also contribute to overall bone health and a decreased risk of osteoporosis.
Blood pressure and heart health: An increased potassium intake can play a huge role in improving vasodilation and lowering blood pressure.
An increase in potassium intake along with a decrease in sodium intake is the most important dietary change that a person can make to reduce their risk of cardiovascular disease, according to Mark Houston, M.D., M.S., an associate clinical professor of medicine at Vanderbilt Medical School and director of the Hypertension Institute at St. Thomas Hospital in Tennessee.3
In one study, those who consumed 4069 mg of potassium per day had a 49% lower risk of death from ischemic heart disease compared with those who consumed less potassium (about 1000 mg per day).3
Unfortunately, according to the National Health and Nutrition Examination Survey, fewer than 2% of US adults meet the daily 4700 mg recommendation.3 Incorporate more potassium-rich sources such as milk, oranges, tomatoes, lima beans, spinach, bananas, prunes and yogurt into your daily diet to increase your potassium intake.
Cancer: The risk of dying from colorectal cancer is highest in geographic locations that receive the least amount of sunlight. Some research suggests that one reason for this is that vitamin D might play a role in cell growth regulation and cancer protection.
According to the National Cancer Institute, "research results overall support a relationship between higher intakes of calcium and reduced risks of colorectal cancer, but the results of studies have not always been consistent."2
Some studies have suggested an increased intake of calcium and lactose from dairy products may help to prevent ovarian cancer.2
Dairy proteins support muscle growth and repair.
Depression: Adequate vitamin D levels support the production of serotonin, a hormone associated with mood, appetite and sleep. Vitamin D deficiency has been associated with depression, chronic fatigue and PMS.
Muscle building and weight loss: Milk is a great source of natural, high quality protein. Maintaining a healthy amount of muscle is important for supporting metabolism and contributing to weight loss and weight maintenance. A diet that is sufficient in protein is needed to preserve or increase lean muscle mass. Dairy proteins support muscle growth and repair. According to Today's Dietitian, a recent analysis of over 20 clinical trials suggested that an increased milk intake can boost muscle mass and strength during resistance exercise in both younger and older adults.6
Recent developments on the possible health benefits of drinking milk from MNT news
A glass of milk a day' may delay knee osteoarthritis in women - knee osteoarthritis currently has no cure but researchers say drinking milk every day has been linked to reduced progression of the disease. Their research was published in the American College of Rheumatology journal Arthritis Care & Research.
Concerns and Precautions
Lactose intolerance is a condition in which a person lacks the enzyme to break down the sugar found in milk for proper digestion. Those with lactose intolerance may experience bloating, flatulence or diarrhea when consuming milk and milk products. Drinking lactose-free milk, which has added enzymes to help with lactose digestion, may ease or eliminate these symptoms.
Milk allergy or hypersensitivity is different from lactose intolerance and refers to an abnormal immunologic reaction in which the body's immune system produces an allergic antibody, called immunoglobulin E (IgE) antibody, which results in allergy symptoms such as wheezing, diarrhea or vomiting. Milk allergy can be manifested as asthma, eczema (an itchy rash), rhinitis (inflamed nose), and gastrointestinal distress, as well as bleeding, pneumonia, and even anaphylaxis (shock).
Consuming too much potassium or phosphorus, both of which are high in milk, can be harmful for those whose kidneys are not fully functional. If your kidneys are unable to remove excess potassium or phosphorus from the blood, it could be fatal.
Consuming an excess amount of calcium is also dangerous. You are unlikely to exceed calcium intake limits with food, however taking an excess amount of calcium via supplements can cause unwanted side effects such as constipation, kidney stones or kidney failure. The tolerable upper intake level of calcium is 2.5 grams per day for healthy individuals over the age of 1 year.
High calcium intakes have been linked with an increased risk of prostate cancer in some studies, however others have found no associations between prostate cancer and calcium intake.2
Written by: Megan Ware, RDN, LD, registered dietitian and nutritionist