There are many different types of milk, all with varying levels of healthfulness.
In western cultures, milk is commonly seen as a vital part of a balanced diet, providing essential nutrients such as calcium, protein, and vitamin D.
Sources of milk and milk products include cows, sheep, camels, goats, and others. "Milk alternatives" include soymilk, almond milk, flax milk, coconut milk, and hemp milk.
This article will focus on cow's milk.
Fast facts about milk
- Milk is a great source of Vitamin D, potassium, and calcium.
- It boasts possible health benefits for the bones, brain, and heart.
- However, milk can aggravate allergies and intolerances to lactose.
- Anaphylactic shock from a milk allergy aggravation can be fatal.
Types of milk and milk products
Milk's healthfulness depends on the individual and the type of milk being consumed.
Pasteurized milk that is high in protein, low in fat, and free of unnecessary additives can be healthful for many people. Flavored milks that contain as much sugar as a can of soda are not.
Present-day cow's milk is not a single product. It can be fresh or long-life, fat-free, lactose-free, fortified with added omega-3s, hormone free, organic, raw, among other options.
Nutritional content
The nutritional breakdown of milk depends on the fat content.
One 244-gram (g) cup of whole milk with 3.25 percent fat and added vitamin D contains:
- 149 calories
- 8 g of fat
- 12.32 g of sugars
- 7.69 g of protein
- 276 milligrams (mg) of calcium
- 205 mg of phosphorus
- 322 mg of potassium
- 124 IU of vitamin D
One 245-g cup of nonfat or skim milk with added vitamins A and D has about:
- 83 calories
- 0.2 g of fat
- 8.26 g of protein
- 12.47 g of sugars
- 299 g of calcium
- 247 mg of phosphorus
- 382 mg of potassium
- 115 IU of vitamin D
Milk also provides choline, magnesium, vitamins A, riboflavin, vitamin B6 and vitamin B12.
Calcium
Calcium has many functions in the body. Its primary job is to develop and maintain healthy bones and teeth.
It is also important for blood clotting and wound healing, maintaining normal blood pressure and muscle contractions, including heartbeat. It may help reduce the risk of some types of cancer.
It is important to try to pair calcium-rich foods with a source of vitamin D to improve absorption.
The National Institute of Health (NIH) recommends 1,000 mg a day of calcium for individuals over 18 years of age. British experts recommend 700mg calcium per day.
Choline
Choline is known as a "vitamin-B like factor." It is an important nutrient that helps with sleep, muscle movement, learning, and memory.
It contributes to:
- maintenance of the structure of cellular membranes
- transmission of nerve impulses
- absorption of fat
- reduction of chronic inflammation
Potassium
High potassium intakes are 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 diet is associated with a 20 percent lower risk of dying from all causes.
The recommended daily intake of potassium for all adults is 4,700 mg per day, but fewer than 2 percent of Americans are estimated to meet this requirement.
Vitamin D (fortified)
Vitamin D is important for the formation, growth, and repair of bones. It also plays a role in calcium absorption and immune function.
Deficiency has been associated with osteoporosis, depression, chronic fatigue, muscle pain, PMS, hypertension, and breast and colon cancer.
Health benefits
The nutrients in milk can benefit the body in various ways.
Bone health
Milk can be good for the bones because it provides vitamin D and calcium. This has been thought to make milk and milk products, such as yogurt, useful in helping to prevent osteoporosis.
However, Harvard research reveals that high calcium intake, even from dairy, is not associated with lower risk of fractures or osteoporosis.
In fact, in countries with some of the lowest calcium intake, around 300mg per day, such as Japan, India, and Peru, bone fractures are lower than in the US.
Other strategies to boost bone health include regular physical activity and strength training, avoiding smoking and eating a diet low in sodium and high in potassium.
Brain health
Researchers from the University of Kansas have found that older adults who consume more dairy products have a higher amount of glutathione, a powerful antioxidant, in the brain.
Those who consumed three daily servings of milk and milk products had antioxidant levels that were approximately 30 percent higher compared to adults who had less than half a serving.
With more research, this study could suggest a new benefit of milk consumption.
Blood pressure and heart health
The high potassium levels in milk can help to protect the heart.
A higher potassium intake and a lower sodium intake are important for reducing the risk of cardiovascular disease, according to the AHA.
In one study, those who consumed 4,069 mg of potassium per day had a 49 percent lower risk of death from ischemic heart disease than those who consumed about 1,000 mg of potassium per day.
Leafy greens like spinach and kale are also good sources of potassium, along with citrus fruits, bananas, tomatoes, and prunes.
However, too high an intake of full-fat dairy products can also increase the risk of atherosclerosis and heart disease.
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 in adults.
Milk provides vitamin D, and it is a good source of calcium. Calcium in milk helps the body absorb vitamin D.
Muscle building and weight loss
Milk is a natural source of high-quality protein, necessary for preserving or increasing lean muscle mass.
A healthy amount of muscle supports metabolism and contributes to weight loss and weight maintenance.
A high-protein diet appears to lead to greater muscle mass and weight loss, but further research is needed to confirm the long-term benefits.
Excess protein can increase acid production and use more calcium from bone to neutralize the acids. This can be detrimental to bone health.
Research from the Nurses' Health Study showed that women who ate 95 grams of protein were more likely to have a broken wrist than women who ate a moderate protein intake of 68 grams per day.
Risks
Some people choose to not consume dairy to follow a vegan diet, a paleo diet, or to try to reduce acne and other conditions.
Some argue that humans are the only species who continue to drink milk after being weaned, indicating that milk consumption is unnatural.
Others have read conflicting research and question the importance of dairy in their long-term health.
Some people avoid milk because it triggers an allergic reaction, or they have a lactose intoleranceor sensitivity.
Allergies, intolerances, and sensitivity
Lactose intolerance can lead to gastrointestinal distress after drinking milk.
A lactose intolerance happens when a person does not have enough of the enzyme needed to break down the sugar found in milk for proper digestion.
For these people, consuming milk and milk products can lead to bloating, flatulence, or diarrhea.
Lactose-free milk has added enzymes to help with lactose digestion. This may ease or eliminate these symptoms.
Levels of lactose intolerance vary between individuals.
One person may tolerate products with low levels of lactose, such as yogurt and hard cheeses. Another may be unable to tolerate even a small amount of milk in their coffee.
A milk allergy is different from lactose intolerance. It refers to an abnormal immunologic reaction, in which the body's immune system produces allergic antibodies, such as immunoglobulin E (IgE).
Symptoms include:
- gastrointestinal distress, with vomiting and diarrhea
- asthma
- eczema
- bleeding
- pneumonia
A severe reaction can trigger sudden anaphylactic shock, which can be fatal.
Those with a milk allergy must strictly avoid milk and dairy in any form, including butter, whey, milk, yogurt, and cheese.
Sensitivity to casein, a protein in milk, is different from an allergy and lactose intolerance. It can trigger inflammation throughout the body, producing symptoms such as sinus congestion, acne flares, skin rash, and migraines.
Many people can consume dairy products without experiencing an adverse reaction.
Anyone who suspects that dairy could be causing symptoms can ask a dietitian to guide them in an elimination diet or recommend food sensitivity testing.
This can help determine whether a dairy-free diet may be appropriate.
Cancer risk
High calcium intake from dairy products is associated with a possible increased risk of ovarian cancer in women, and high calcium intake from any source can cause prostate cancer in men.
Flavored milks
Flavored milks with added sugar, syrups, artificial sweeteners, binders, and other ingredients are not generally a healthful option.
Checking the ingredients on the label can help the consumer to check what it is in the pack.
While research supports long-term calcium intake from a variety of sources for overall health, it remains unclear if more than one serving of dairy a day is necessary or beneficial to reduce bone fracture risk.
Each person needs to make their own, informed decision to follow a healthful diet.
What suits one person may not suit the next.
A registered dietitian can help an individual make the right decision.
