Cow's milk is a staple for many and has been for millennia. It can provide protein, calcium, and vitamins B-12 and A, among other benefits. It can be a nutritious part of a varied diet. While it's still a popular food, recent studies suggest milk may have harmful effects on the body. Other research, however, points out the health benefits of dairy.
Nutritional Composition of Milk
Milk is considered a whole food. It provides 18 out of 22 essential nutrients. Milk nutrition varies. Dairy products provide a package of essential nutrients that is difficult to obtain in low-dairy or dairy-free diets, and for many people it is not possible to achieve recommended daily calcium intakes with a dairy-free diet.
Milk also provides:
- Iron
- Selenium
- Vitamin B-6
- Vitamin E
- Vitamin K
- Niacin
- Thiamin
- Riboflavin
Fat content varies. Whole milk contains more fat than other types:
- Saturated fats: 4.5 grams
- Unsaturated fats: 1.9 grams
- Cholesterol: 24 milligrams (mg)
Potential Health Benefits of Milk Consumption
Despite the established benefits for bone health, some people avoid dairy in their diet due to beliefs that dairy may be detrimental to health, especially in those with weight management issues, lactose intolerance, osteoarthritis, rheumatoid arthritis, or trying to avoid cardiovascular disease. This review provides information for health professionals to enable them to help their patients make informed decisions about consuming dairy products as part of a balanced diet. There may be a weak association between dairy consumption and a possible small weight reduction, with decreases in fat mass and waist circumference and increases in lean body mass. Lactose intolerant individuals may not need to completely eliminate dairy products from their diet, as both yogurt and hard cheese are well tolerated. Among people with arthritis, there is no evidence for a benefit to avoid dairy consumption. Dairy products do not increase the risk of cardiovascular disease, particularly if low fat. Dairy products have been an important part of the human diet for some 8000 years and are part of the official nutritional recommendations in many countries worldwide. They provide a package of key nutrients that are difficult to obtain in diets with limited or no dairy products, such as vegan or dairy restrictive diets. Indeed, dairy products are rich in calcium, protein, potassium and phosphorus. They contribute around 52-65 % of the dietary reference intake (DRI) of calcium and 20-28 % of the protein requirement, depending on the age of the consumer.
Read also: Milk on Carnivore: Benefits & Risks
Bone Development and Health
Milk may help improve weight and bone density in children, according to a 2015 study. It also reduces the risk of childhood fractures. Older research shows that pregnant women who ate a healthy diet that included plenty of dairy- and calcium-rich foods had children with better bone growth and mass, compared with women who followed less healthy diets. Milk also provides proteins that are necessary to build and maintain healthy bones, teeth, and muscle. A cup of milk provides around 7 to 8 grams of casein and whey proteins. A cup of milk contains almost 30 percent of the daily requirement of calcium for adults. Milk also contains potassium and magnesium. These minerals are important for healthy bones and teeth. Most milk has added vitamin D. A cup of fortified milk contains about 21 percent of the recommended daily amount. Vitamin D is an important vitamin that plays many roles in the body, including promoting calcium absorption and bone mineralization. There is growing evidence that the consequences of age-related or postmenopausal bone loss on fracture risk depend on the level of peak bone mass achieved during childhood and adolescence, as well as on the rate of bone loss. Maximizing peak bone mass may be an important contributor to fracture risk reduction in children as well as in the elderly. While 60-80 % of the variance in peak bone mass is explained by genetic factors, the remainder may be amenable to interventions aimed at maximizing it. Such interventions include increasing physical activity and decreasing exposure to risk factors such as cigarette smoking and excessive alcohol intake, as well as optimizing nutrition. The importance of dietary calcium for bone growth is evident even prior to birth. Diets rich in calcium and other micronutrients (as supplied by dairy foods, green leafy vegetables, fruits) given to pregnant women are associated with increased skeletal growth and/or bone mass/density in the offspring, with beneficial effects on bone size and BMD apparent up to the ages of 6-9 years. During childhood, the available data indicate that dairy products are important for growth and bone health. In growing children, long-term milk avoidance is associated with smaller stature, lower bone mineral mass, and increased fracture risk before puberty of around 2.7-fold higher than a matched birth cohort. The largest randomised controlled trial (RCT) with dairy products found significantly higher gains in height, body weight, bone mineral content (BMC) and BMD in school girls aged 10 years receiving milk on school days for 2 years compared with the control group. This significant increase in bone mass following calcium enrichment of the diet observed in pre-pubertal girls and boys was maintained for 1-3 years after the end of the trial, suggesting a possible optimization of peak bone mass when calcium supply is sufficient. Increasing dairy product consumption in girls aged 10-12 years was found to be more beneficial for cortical bone mass accrual than calcium supplementation in tablet form for the same calcium intake (1000 mg/d). In summary, numerous observational studies and RCTs have shown a favourable effect of dairy products on bone health during childhood and adolescence. European guidance on osteoporosis incorporates nutritional recommendations for bone health, including at least 1000 mg/d calcium and 800 IU/d vitamin D.
Diabetes Prevention
Type 2 diabetes is a disease characterized by high blood sugar levels. Diabetes can increase your risk for:
- Heart disease
- Stroke
- Kidney disease
A 2020 published review concluded that the type of fat in dairy products, including milk, plays a beneficial role in preventing type 2 diabetes in adults. This may be because milk proteins improve your blood sugar balance.
Heart Health
Milk fat may help raise levels of HDL (good) cholesterol. Having healthy HDL cholesterol levels may prevent heart disease and stroke. Additionally, milk is a good source of potassium. This mineral helps regulate blood pressure.
Appetite Control and Weight Management
Drinking milk hasn’t been linked to weight gain or obesity, and it may help curb appetite. An older study of 49 people showed that dairy helped people feel fuller and reduced how much fat they ate overall. Some studies have shown that full fat dairy intake is not associated with lower body weight. And some have shown that dairy intake, in general, may prevent weight gain. There may be a weak association between dairy consumption and a possible small weight reduction, with decreases in fat mass and waist circumference and increases in lean body mass.
Read also: Paleo Diet and Milk
Potential Risks and Considerations
Despite the potential benefits, it's important to be aware of the possible risks associated with milk consumption.
Acne and Skin Conditions
A 2016 study found that teenagers with acne drank higher amounts of low fat or skim milk. Low fat dairy may also trigger adult acne. Other studies have linked acne to skim and low fat milk. This may be due to milk’s influence on certain hormones, including insulin and insulin-like growth factor-1 (IGF-1). More research is needed to explore the diet-acne connection. Some foods may worsen eczema, including milk and dairy, according to a clinical review. However, a 2018 study found that pregnant and breastfeeding women who added a probiotic to their diet reduced their child’s risk for eczema and other food-related allergic reactions. Dairy may also be a trigger food for some adults with rosacea. On the other hand, a recent study suggests that dairy may actually have a positive effect on rosacea.
Allergies
Up to 7.5 percent of children have a milk allergy, estimate some experts. It can cause skin reactions, such as eczema, and gut symptoms, such as:
- Colic
- Constipation
- Diarrhea
Other serious reactions include:
- Anaphylaxis
- Wheezing
- Difficulty breathing
- Bloody stool
Children may grow out of a milk allergy. Adults can also develop a milk allergy.
Read also: Nutritional Profile of Rice Milk
Cancer Risk
Excess calcium from milk and other foods may increase the risk of prostate cancer. Milk sugars may be linked to a slightly higher risk of ovarian cancer.
Lactose Intolerance
Cow’s milk has a higher amount of lactose than milk from other animals. A 2017 review estimates 65 to 70 percent of the world’s population has some form of lactose intolerance. Most people with this condition can safely add small amounts of dairy to their diet. Lactose intolerant individuals may not need to completely eliminate dairy products from their diet, as both yogurt and hard cheese are well tolerated.
Risks Associated with Raw Milk
Over the last few years, interest in drinking unpasteurized milk has grown, with some people claiming a wide range of health benefits. Most of those health benefits, however, are not backed by science and drinking raw milk may do more harm than good. The biggest health risk associated with raw milk comes from microorganisms and enzymes that can enter the milk at many different points from milking to the sale. Bacteria that commonly cause food-borne illness, such as salmonella, listeria, and E. coli, can be prevented by pasteurizing milk products. These bacteria can cause severe infections in the digestive tract, often leading to vomiting, diarrhea, fever, and blood in the stool. Most people who contract an infection from a food-borne pathogen can recover at home within a few days, but severe cases can lead to reactive arthritis, organ damage, blood infections, and even death. One review of 20 years of data on food-borne illnesses related to drinking raw milk found that, in that time frame, 202 outbreaks and 2,645 illnesses were linked to raw milk. Of those reported illnesses, 228 required hospitalizations, and three people died. A broader review found that, from 2009 to 2014, there were 706 illnesses and 22 hospitalizations each year, on average, associated with raw milk and products made from raw milk, such as cheese. In 2017, it was estimated that only 3.2 percent of the population of the United States drank raw milk, but that 96 percent of the dairy-related food-borne illness were caused by consuming raw milk or related dairy products. These numbers are only based on reported illness, and it's likely that the real numbers of food-borne illnesses related to raw milk are significantly higher. Even with good food safety practices in place, we occasionally see an outbreak in cheeses, ice cream and other products due to cross contamination in a factory or other lapse in safety. Unfortunately, people are susceptible to fads such as drinking raw milk, and don’t realize how dangerous these illnesses can be, especially in pregnant women, older people, and immunocompromised people. The H5N1 bird flu, which has spread to farm animals, could also contaminate raw milk. One report indicated that bird flu was found in more than one-third of the samples of commercial cow milk-but also found that pasteurizing the milk killed the virus. While the risk to humans of contracting bird flu remain low, a recent study from St. Jude's found that the current antivirals available to treat bird flu are less effective when the virus is contracted orally-such as in drinking raw milk. Some influencers have stated that raw milk will cure a person's allergies or asthma, but there is no scientific proof to back up these claims. There was a study done in 2007, based on a larger study of allergies among European children living in more rural areas, that stated farm milk may help protect against allergies in children. It is important to note the phrase "farm milk," as the study authors were unable to determine if the milk was raw or if it had been pasteurized-they only knew that it came from a farm. That same study also states "However, raw milk may contain pathogens such as salmonella or EHEC, and its consumption may therefore imply serious health risks." One thing to also note is that allergies and asthma are also influenced by a person's environment. If one child grows up in a city, with more air pollutants, and another child grows up on a farm, with fewer air pollutants, the child on the farm is less likely to have allergies or asthma, regardless of the milk they drink. Lactose is found in all milk-even raw milk. No milk, raw or pasteurized, contains anything that would suddenly introduce lactase into the digestive system. Probiotics do not naturally occur in foods, meaning you can't get them from consuming raw fruits or vegetables or raw milk. Consuming raw milk and raw milk products comes with a lot of risk and not much, if any, reward.
Alternatives to Cow's Milk
Plant and nut-based milks are suitable for individuals who are lactose intolerant or vegan include:
- Soy milk
- Almond milk
- Flax milk
- Coconut milk
- Hemp milk
Recommendations and Considerations
Milk is naturally packed with essential nutrients in a convenient and accessible form. Drinking milk is particularly important for children. It may help you and your child maintain good health. Milk and dairy products, such as cheese and yoghurt, are great sources of protein and calcium. They can form part of a healthy, balanced diet. Unsweetened calcium-fortified dairy alternatives, made from plants like soya, coconuts or oats, also count as part of this food group. The total fat content of dairy products can vary a lot. To make healthier choices, look at the nutrition information on the label to check the amount of fat, including saturated fat, salt and sugar, in the dairy products you're choosing. Milk and dairy foods is saturated fat. For older children and adults, eating too much fat can contribute to excess energy intakes, leading to becoming overweight. A diet high in saturated fat can also lead to raised levels of cholesterol in the blood, and this can put you at increased risk of having a heart attack or stroke.
For older children and adults, it's a good idea to go for lower-fat milks because having too much saturated fat in your diet can lead to high cholesterol. If you're trying to cut down on fat, try swapping to 1% fat or skimmed milk, as these still contain the important nutritional benefits of milk, but are lower in fat. It’s ok to use 1% fat or skimmed milk when cooking for children over the age of 12 months. But do not give them as a main drink to children under the age of 5.