Dairy foods include a range of food and beverage products that make up classic combinations: cereal with milk, cheese and crackers, yogurt and berries, ice cream sundaes. While ice cream and cream cheese are examples of indulgent dairy foods that are viewed as every-so-often treats, a lack of clarity exists over other dairy foods that offer protein, calcium, vitamin D, and other healthful nutrients. Is cheese a healthy food? Is non/low-fat milk and yogurt better for the heart than full-fat versions? Traditionally, whole milk dairy products have been viewed as the less healthful choice because of their predominant type of fat—saturated fat.
Saturated fats were targeted in the 1970s and 1980s as potentially causing harm to health. The Dietary Guidelines for Americans in 1980 recommended choosing non/low-fat dairy foods in place of full-fat versions (except for young children). In 2010, the Healthy, Hunger-Free Kids Act required schools in the U.S. to replace whole milk with non/low-fat unflavored milk or non-fat flavored milk. Sales of low-fat and fat-free milks, yogurts, and cheeses skyrocketed despite complaints about their lack of flavor and satisfaction. The 2015-2020 Dietary Guidelines recommend three 1-cup (8 ounce) servings of non/low-fat milk or similar amounts of low-fat cheese, yogurt, or other dairy foods for adults and children over 9 years old to increase calcium intake and reduce the risk of bone fractures. [1]
To the surprise of many, research in the 2000s defied these longstanding guidelines to suggest that full-fat dairy foods might be just as healthful as their lower-fat counterparts, provoking scientists to look more closely at all dairy products. Upon closer examination, they realized that dairy foods are not one and the same. The fermentation process required to make cheese and yogurt may impart unique health benefits as well as improved digestibility from a lower lactose content. That said, how people eat dairy is important to consider. Take cheese for example: is it consumed melted on fast-food burgers, pasta, and pizza that are already high in refined carbohydrate, sodium, and saturated fat? Or is it served in thin wedges, eaten with fresh fruit as a snack or dessert? Another key point is frequency and amount. If people drink several glasses of low-fat milk or snack on reduced-fat cheese throughout the day, they might end up eating as much saturated fat (or more) than if they had consumed one glass of whole milk or serving of full-fat cheese.
These questions are important to consider when reviewing scientific research on dairy foods.
What is lactose, and what causes lactose intolerance?
Lactose is the naturally occurring sugar found in milk and all dairy products. The body breaks down the sugar molecule and digests it with the help of an enzyme called lactase. Some people have low levels of lactase due to genetics, digestive problems, or gastrointestinal surgeries that interfere with its production. Without lactase, the undigested lactose passes into the small intestine where bacteria ferment it, producing symptoms of gas, bloating, diarrhea, or constipation.
Dairy foods like milk, ice cream, cream, and soft cheeses like cottage and ricotta are high in lactose. Yogurt and aged cheeses are low in lactose because their production involves fermentation by natural bacteria that break down and consume the lactose. This is why some people with lactose intolerance may be able to safely consume some types of cheese and yogurt without side effects. Lactaid pills are a commercial product that contains the lactase enzyme that breaks down lactose, and can be taken before meals containing dairy to help reduce uncomfortable side effects. Lactaid milk is cow’s milk that contains the lactase enzyme so the product is very low in lactose.
Dairy and Health
The nutrients and types of fat in dairy are involved with bone health, cardiovascular disease, and other conditions. Calcium, vitamin D, and phosphorus are important for bone building, and the high potassium content of dairy foods can help lower blood pressure.
Studies on dairy have limitations that may be a cause of seemingly conflicting findings. In observational studies, people who consume a high amount of milk may be different from those who do not in ways that are not fully captured by statistical adjustments. Randomized clinical trials tend to be short in duration with a small number of participants, making it difficult to see possible effects of dairy intake on chronic diseases like heart disease and bone fractures that take years to develop. Thus, longer-term epidemiological studies may provide additional insights.
Bone health
The recommendations for dairy foods from the Dietary Guidelines for Americans 2015-2020 are based on short-term clinical trials that have shown that higher intakes of calcium result in small increases in bone mineral density. However, after one year the differences in bone density are not significant compared with a placebo. [2] Meta-analyses of prospective studies have not found an association of total dairy food intake and hip fracture risk. [3,4]
The effects of dairy foods are of special interest with children due to calcium and vitamin D playing an important role in bone growth. These nutrients are essential, but the critical question is the amount needed to minimize bone fracture risk.
A randomized controlled trial followed 240 girls and boys between the ages of 9-16 years for 18 months who had a lower dairy intake at baseline (less than 800 mg of calcium daily). It found no differences in bone mineral density in children who ate up to 3 servings versus 2 servings of dairy daily. [5] These findings suggest that more than two servings per day will not increase bone mineral density.
A large cohort study following 96,000 men and women over 22 years did not find that greater intakes of milk during teenage years was associated with a lower risk of hip fractures later in life. [6] In fact, each additional glass of milk per day during teenage years was associated with a 9% greater risk of hip fracture in men. Part of this risk was related to a taller height, an independent risk factor for hip fractures. No association was found in teenage girls.
Sometimes research looks at calcium intakes compared with calcium balance (how much calcium is eaten from foods and supplements compared with how much calcium is lost by the body). Calcium balance is positive during growing phases, such as in childhood and adolescence. Calcium balance is negative in the elderly, when the risk of bone loss increases. Studies have found that amount of calcium needed to achieve positive calcium balance varies among groups of people. Although the U.S. recommendation of about 3 cups daily of milk or dairy foods daily provides about 900-1000 mg calcium, some studies have shown that children and adults can achieve positive calcium balance with as little as 400 mg daily. [7,8]
Cardiovascular disease
More than half of the type of fat in dairy is saturated, which is a known risk factor for heart disease and the reason why the Dietary Guidelines for Americans recommends only non/low-fat dairy products. However, removing one type of food from the diet usually means replacing it with another. Swapping saturated fat with low-fat foods but also possibly more refined carbohydrates may help to lower LDL “bad” cholesterol but can raise triglycerides, a different risk factor for cardiovascular disease. High blood levels of triglycerides can lead to hardening of the arteries.
Based on large cohort studies, dairy foods appear protective from cardiovascular disease compared with similar servings of red meat or refined carbohydrates. However, an increased risk of cardiovascular disease is seen eating dairy foods in comparison with fish, nuts, or unsaturated fats. The results were similar with full-fat versus low-fat dairy. [9-11]
The PURE (Prospective Urban Rural Epidemiology) study, a large multinational cohort following more than 136,000 participants from 21 countries for nine years looked at the relationship between dairy intake and mortality and cardiovascular disease. [12] It found that a higher intake of dairy (2+ servings daily), specifically milk and cheese, compared with no intake was associated with a 17% lower risk of death from any cause and 14% lower risk of cardiovascular disease and 34% lower risk of stroke. A higher intake of saturated fat from dairy sources was not associated with death or CVD. The PURE study included primarily low-income and middle-income countries where refined carbohydrates are a greater part of the diet and dairy foods are less commonly eaten. Therefore, in countries where food variety is more limited, adding a moderate amount of dairy may show a benefit with cardiovascular health if it replaces carbohydrate in the diet.
Diabetes
The evidence on dairy foods and their relation to type 2 diabetes mellitus (T2DM) is inconclusive. While population studies on total dairy intake tend to show little or no association with T2DM, closer evaluations of specific foods like yogurt suggest a possible protective effect. The protein and probiotics in yogurt may help to lower blood glucose and affect gut microbiota that prevents weight gain. [13]
A meta-analysis of 22 cohort studies with more than 579,000 individuals found a weak association between higher total dairy intake (both full-fat and low-fat types) and lower risk of T2DM. [14] When specifically looking at yogurt, the study found a stronger association of reduced diabetes risk with moderate intakes.
A prospective study of three large cohorts of 194,458 men and women from the Health Professionals Follow-up Study and the Nurses’ Health Study I and II found that total dairy intake including high and low-fat dairy was not associated with risk of T2DM. [15] However, one serving of yogurt daily was associated with a 17% reduced risk of diabetes.
The types of saturated fats in dairy have also gained greater attention, as some types of saturated fatty acids in dairy are different than those in red meat, and may have a more neutral effect on blood cholesterol. A study of 3,333 adults from the Nurses’ Health Study and Health Professional’s Follow-up Study assessed the participants’ blood levels of various dairy fatty acids. [16] It found that higher blood levels of these saturated fatty acids were associated with less incidents of T2DM. However, it is possible the metabolic abnormalities that precede the diagnosis of T2DM by many years may have affected the blood levels of these fatty acids.
Weight
It has been speculated that although full-fat dairy contains more calories and fat than reduced-fat dairy, full-fat versions may taste better and be more filling. This in turn might prevent extra snacking between meals or even eating less over the course of a day. However, randomized clinical trials have not shown an overall effect of dairy foods on weight loss or body weight changes. [17] In a large prospective study of three cohorts of men and women, intakes of low-fat and whole milk and cheese had no association with weight changes, though yogurt in the diet was associated with less weight gain over time. [18]
Cancer
The fat in dairy foods contains estrogenic hormones that are associated with a higher risk of some hormone-related cancers. High amounts of dairy foods in the diet have been associated with certain cancers, including endometrial and prostate, but with a lower risk of colorectal cancer. Findings for breast cancer have not been consistent [8].
A prospective study of 68,019 women found that total dairy intake was associated with a greater risk of endometrial cancer among postmenopausal women who were not receiving hormone therapy, [19] a finding possibly related to the sex-hormone content of dairy products.
A prospective study of 926 men from the Physicians’ Health Study diagnosed with non-metastatic prostate cancer and followed for up to 10 years looked at dairy intake in relation to cancer deaths. [20] Men eating three or more servings daily of total dairy products had a 76% increased risk of deaths from all causes and 141% increased risk of death from prostate cancer compared with those who ate less than one dairy food a day. There was little difference in risk between high-fat and low-fat dairy.
A 2014 meta-analysis found that high intakes of dairy products, milk, low-fat milk, cheese, and total, dietary, and dairy calcium, but not supplemental or nondairy calcium, may increase total prostate cancer risk. According to the authors, the results suggest that other components of dairy foods rather than fat and calcium may increase prostate cancer risk. [21]
The World Cancer Research Fund reports strong evidence that dairy foods decrease the risk of colorectal cancer. This is likely due, at least in part, to their high content of calcium. [22] A study following 477,122 men and women for 11 years looked at whole-fat and low-fat dairy foods and colorectal cancer; it did not find a difference in the apparent protective effect of dairy foods based on the fat content. [23]
In one prospective study of 52,795 North American women, higher intakes of milk (but not cheese or yogurt) were associated with greater risk of breast cancer. [24] However, in another study of diets in adolescents, milk intake was shown to be unrelated to a future risk of breast cancer. [25]
For Your Health and the Planet’s Health
The production of dairy foods places considerable demand on land, water, and other natural resources, and dairy-producing ruminant animals like cattle, sheep, and goats generate methane—a powerful greenhouse gas. In identifying a dietary pattern both healthy for people and sustainable for the planet, the “planetary health diet” sets the target for dairy foods at 250 grams per day (with a range of 0 to 500 grams per day). 250 grams is about one (8-ounce) cup of milk, yogurt, or equivalent amounts of cheese (because milk is about 90% water, this amounts to about 1 oz of hard cheese). If everyone were to consume 2 servings of dairy per day, climate change would be difficult to control. [26]
Bottom Line
Both full-fat and non/low-fat dairy foods can be good sources of protein, calcium, B vitamins, and vitamin D. Dairy foods that undergo fermentation, such as yogurt and some cheeses, are lower in lactose and contain healthful gut bacteria that may benefit digestive health. However, the nutrients in milk can be found in other foods and therefore it is not an essential food even for the normal growth and development in children and for the prevention of health conditions like bone fractures.
Although full-fat dairy foods are high in saturated fat, whether full-fat dairy is more harmful (or more beneficial) to health than non/low-fat dairy will depend on the sources calories that replace the dairy fat. If this is sugar there may be little difference, but if this is unsaturated fat (such as in nuts or plant oils), the lower fat version would be better. The total amount of dairy consumption is also important; at only one serving per day, the amount of fat would not be important, whereas it would with 3 or more servings per day. Thus, while more research emerges, the type of dairy one incorporates into their dietary pattern can be a matter of personal preference. Some people enjoy using non-fat milk in their cereal or eating a low-fat Greek yogurt. Others may find that choosing a richer full-fat yogurt as an afternoon snack works well to prevent extra snacking before dinner. The overall dietary pattern is key, and creating a balanced plate allows for 0 to 2 servings daily of dairy (of any type) can be healthy.
Learn more about some specific types of dairy foods:
Research on milk and health often produces contrary findings. Some reasons may be the wide range of different nutritional qualities in milk and how milk intake is measured. Learn more about this popular beverage.
Countries around the world have experimented with cheese-making, varying the types of milk, how long the cheese is allowed to age and ripen, and using different additives like salt or acid to produce unique textures and flavors.
References
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Dehghan M, Mente A, Rangarajan S, Sheridan P, Mohan V, Iqbal R, Gupta R, Lear S, Wentzel-Viljoen E, Avezum A, Lopez-Jaramillo P. Association of dairy intake with cardiovascular disease and mortality in 21 countries from five continents (PURE): a prospective cohort study. The Lancet. 2018 Nov 24;392(10161):2288-97.
Chen M, Sun Q, Giovannucci E, Mozaffarian D, Manson JE, Willett WC, Hu FB. Dairy consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis. BMC medicine. 2014 Dec 1;12(1):215.*Disclosure: DM is a member of the Unilever North America Scientific Advisory Board.
Gijsbers L, Ding EL, Malik VS, De Goede J, Geleijnse JM, Soedamah-Muthu SS. Consumption of dairy foods and diabetes incidence: a dose-response meta-analysis of observational studies. The American journal of clinical nutrition. 2016 Apr 1;103(4):1111-24.*Disclosure: SSS-M, KMG, and ELD reported receiving prior funding from one or more of the following: Dairy Research Institute, Global Dairy Platform, Dutch Dairy Association, and Dairy Australia. Any prior sponsors had no role in the design and conduct of the study, data collection and analysis, interpretation of the data, decision to publish, or preparation of this manuscript.
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Last reviewed October 2020
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