Although people tend to accept that fruits and vegetables are healthful options, other food groups, such as dairy, spark more discussion and seem to have conflicting recommendations.
The United States Department of Agriculture (USDA) Choose My Plate recommendations state that adults should consume 3 servings of dairy products per day. Children should consume around 2 or 2.5 servings per day, depending on their age.
Examples of typical servings of dairy include:
- 1 cup of milk
- 1 cup of yogurt
- 1 ounce of hard cheese, such as cheddar or Monterey Jack
- half a cup of cottage cheese
For decades, the USDA have advised people to consume milk every day. However, some health advocates believe that people do not need to eat dairy to be healthy. Others believe that dairy may even be bad for health if people consume too much of it.
These mixed messages can be confusing. In this article, we break down what the evidence says.
Calcium is a necessary mineral. It helps build strong bones and is necessary for other functions, such as muscle contraction and nerve transmission.
Dairy products are a good source of calcium, and this is one of the main reasons that the USDA and the National Institutes of Health (NIH) recommend that people consume dairy.
Without enough calcium, a person may be at risk of osteoporosis. This condition causes bones to weaken and leaves them prone to breaking. The National Osteoporosis Foundation explain that people need adequate calcium and vitamin D to prevent bone loss and osteoporosis.
Although dairy products may contain more calcium than many other foods, evidence suggesting that consuming dairy can prevent bone fractures seems conflicting.
For example, one systematic review and meta-analysis suggests that as dairy intake increases, the risk of osteoporosis and hip fracture decreases in some studies. However, this was not the case in all the studies included in the analysis.
It is also important to explain that many other factors can affect bone health, including exercise, smoking status, alcohol use, and changes in hormone levels during aging.
One long term Swedish study that involved more than 61,000 women and 45,000 men found a potential link between higher milk intake and higher mortality and higher incidence of bone fractures.
However, this association does not indicate a "cause and effect" relationship. For example, the women who had hip fractures and higher milk intake may have been drinking more milk because they were at risk of hip fractures.
The study authors caution that the results do not take into consideration other lifestyle factors and health conditions.
Another long term study of 94,980 Japanese people found the opposite association, with a lower risk of mortality tied to increased milk consumption.
Overall, the majority of research on dairy suggests that milk is beneficial for bone health and cardiovascular health.
One thing that is clear is that calcium and the other nutrients that milk provides are necessary for bone health.
Those who cannot or choose not to consume dairy should consume other calcium-rich foods or speak to a doctor about whether they need a calcium supplement.
Saturated fats are present in full fat dairy products such as whole milk, butter, and cream, and to a lesser extent, in reduced fat dairy products such as 1% milk. Saturated fats are also present in meat, some processed foods, coconut oil, and palm oil.
The American Heart Association (AHA) say that saturated fats can lead to high cholesterol and heart disease. As a result, many full fat dairy products do not appear in heart-healthy diet recommendations.
The AHA advise people to choose fat free or low fat dairy products to obtain calcium without the saturated fat. The National Heart, Lung, and Blood Institute also recommend that people choose low fat or fat free dairy products as part of a healthful diet.
However, recent evidence suggests that the link between saturated fat and heart disease is not as strong as people once believed. One review states that some people have exaggerated the role of saturated fat in heart disease. Again, many other lifestyle factors are important when it comes to evaluating heart disease risk.
A team of cardiologists wrote an article stating that eating foods with saturated fat does not clog the arteries, as people once believed. They contend that the "fat free" movement caused higher intakes of carbohydrate foods, including sugars. This might explain why rates of heart disease have increased.
Another article states that numerous analyses and reviews do not support the belief that eating saturated fat is linked to heart disease. The article also mentions that saturated fat could lower the risk of obesity-related diabetes in some cases.
Although the links between full fat dairy and heart disease are no longer clear, there are other things a person can do to adopt a heart-healthy lifestyle, including:
- eating plenty of fruits and vegetables
- exercising regularly
- not smoking
- limiting alcohol consumption
- getting adequate amounts of sleep
- controlling blood sugar levels, if they have diabetes
People should also speak with a health professional about how often they need blood pressure checks, cholesterol and glucose tests, and other measures that can predict heart disease risk.
Diabetes is a common health condition, with diabetes and prediabetes affecting more than 100 million people in the U.S. Although many factors influence whether or not a person will develop diabetes, diet is one important aspect.
The Mediterranean diet emphasizes the consumption of healthful fats from olive oil and fish, as well as fruits, vegetables, whole grains, and moderate amounts of dairy.
A meta-analysis found that consuming dairy, particularly yogurt, could have a protective effect against type 2 diabetes. Another study found that the people who consumed the most high fat dairy products had a 23% lower risk of developing type 2 diabetes than those who consumed the least amount of high fat dairy.
Dairy may fit into a healthful diet for many people who have type 2 diabetes. As each person is different, it is best to speak with a doctor or nutritionist about diet recommendations for good blood glucose control and management of diabetes.
Milk contains a number of nutrients that are beneficial to health. It contains a complete protein, which means that it contains all the amino acids that are essential for health. It also contains other vitamins and minerals that other foods provide limited amounts of.
One cup of fortified whole milk contains:
- Calories: 149
- Protein: 7.69 grams (g)
- Carbohydrate: 11.7 g
- Fat: 7.93 g
- Calcium: 276 milligrams (mg)
- Vitamin D: 3.7 international units (IU)
- Vitamin B-12: 1.1 mcg
- Vitamin A: 112 IU
- Magnesium: 24.4 mg
- Potassium: 322 mg
- Folate: 12.2 IU
- Phosphorus: 205 mg
Most milk manufacturers fortify their products with vitamins A and D. A person can see whether milk is fortified by reading the ingredients label. The label will list the added vitamins, such as vitamin A palmitate and vitamin D-3, as ingredients.
Milk is a nutrient-rich drink, offering many nutrients that other beverages such as sports drinks, sodas, and other nondairy milk substitutes are lacking.
Dairy products contain a sugar called lactose. To digest lactose, a person's small intestine must produce an enzyme called lactase.
Without enough lactase, a person will not be able to digest dairy products that contain lactose. This leads to symptoms of lactose intolerance, which may include:
- stomach pain
Lactose is also present in human breast milk. Most babies are able to digest it without issues. In fact, lactose intolerance in infancy is a rare disorder.
However, many people become lactose intolerant as their body slows down its production of lactase. About 65% of the world's population have a "reduced ability to digest lactose after infancy."
Some dairy products that are fermented, such as yogurt and certain hard cheeses, contain lower amounts of lactose than a glass of milk. These types of fermented products may be suitable choices for some people who are sensitive to lactose.
Other people find that almost any amount of dairy causes symptoms. People who cannot digest dairy may wish to consume lactose reduced dairy milk or fortified soy milk alternatives. Other nondairy milk alternatives do not provide similar nutrition.
The majority of reliable evidence suggests that dairy can be an important nutrient-rich choice for a healthful diet. However, it is up to each individual to decide whether or not to consume it.
People who do not or cannot consume dairy should obtain calcium from other sources, such as fortified nondairy soy milk, leafy green vegetables, and other calcium-rich foods.
People may wish to speak with a health professional about their dietary needs based on their health history and lifestyle.