Milk features in the nutrition guidelines in nearly every country in the world. Clearly it has some beneficial attributes, but it also receives a lot of negative publicity. As we discussed in the previous blog there can be some real downsides to milk consumption for some individuals. However, there are also many myths. The aim of this blog is to separate the facts from the myths.
The pros of milk
Milk is a source of very high-quality protein, in fact the highest quality protein known of (whey protein) makes up around 20% of the protein in milk, with the other 80% coming from casein, another high-quality protein. (read more on "what is whey protein?" is in this blog). These are both complete proteins, that are also high in leucine. Protein is important for recovery and adaptation from training, as well as for general health.
Calcium in milk
Milk and other dairy products are high in calcium, which is essential for healthy bones. Milk is promoted particularly to children and young people, whose bones are still developing and require more calcium than adults. Consuming enough calcium can help to reduce osteoporosis (a condition involving brittle and weak bones) which is common as people age, and particularly common in women. Although some people suggest that calcium from milk and dairy is poorly absorbed and assimilated due to the protein content, studies have shown that giving people dairy products is more effective at increasing bone mineral density than calcium supplementation.
Vitamins in milk
Milk also contains vitamins that are essential for health such as vitamin A. Some countries also fortify their milk with vitamin D, though it is probably best absorbed from whole milk due to its fat content. Milk is an excellent source of B12 which is difficult to obtain from non-animal foods, so it can be a useful source for vegetarians.
Milk for recovery
In an exercise setting, milk is an excellent recovery drink. As well as containing high quality protein, it is high in carbohydrate from the milk sugar lactose. This carbohydrate is a disaccharide (meaning it is made up of two individual sugars) of glucose and galactose. This combination of sugars has been shown to be excellent at restoring glycogen stored in the liver, which is particularly important for recovery from exercise in the short-term. Milk also contains electrolytes and has been shown to be very effective at promoting rehydration after exercise – in some cases better than commercial sports drinks. Chocolate or flavoured milk has also been suggested to be particularly useful for recovery, because as well as containing all of the other nutrients, it contains added sucrose. This helps deliver carbohydrate post-exercise, which is the main factor in recovering exercise performance post-exercise. It is also cost-effective and easy to drink the required amounts.
The cons of milk
Milk is certainly not without possible downsides, especially for certain people who cannot eat certain, or any dairy foods. Dairy allergies are the most common childhood allergy, and although most children resolve their allergy by the age of 5, the allergy continues on into adulthood for many (read our previous blog on the health effects of milk here).
The symptoms can range from severe, including anaphylaxis, to less serious (but still unpleasant), such as diarrhoea, vomiting, dermatitis and wheezing. For anyone with a dairy allergy, usually all dairy foods must be avoided, as anything with dairy proteins in could trigger a reaction. For anyone with a dairy allergy, milk is not an option.
A condition often confused with dairy allergy is lactose intolerance. Lactose is the natural sugar found in milk, and in varying amounts in different dairy foods. It requires an enzyme (lactase) in the gut to break it down. Although humans are born with this enzyme, the amount reduces to very low levels after childhood in a majority of the world’s population, meaning that as much as 60-70% of the world’s population experiences unpleasant gastrointestinal symptoms when they eat more than a certain amount of lactose. Certain ethnic groups have better responses to lactose, which is allowed by genetic mutations linked to cattle rearing and dairy consumption in ancestral times. This includes most Caucasian people (especially those from Northern and Western Europe) as well as some groups in West Africa and the Middle East. For those with lactose intolerance, only relatively small amounts of milk (250-300ml or 1 cup) can be consumed without symptoms. Some sufferers even struggle with less, therefore limiting access to the benefits of milk.
The myths of milk
Milk has been part of the human diet for 8,000-10,000 years, and over this time many myths have developed. As well as ancient myths about milk, such as the Fulani people believing the world began with a drop of milk, or the Norse myth of the world being fed by the milk of a primeval cow there are also more modern myths.
Milk and inflammation myth
Milk is often stated to be a pro-inflammatory food, causing increases in inflammatory markers and whole-body inflammation. However, studies have repeatedly shown that milk and dairy are not inflammatory, and in fact may be anti-inflammatory in a few health conditions. A recent meta-analysis again confirmed that there was no evidence that milk causes inflammation. The authors concluded: The consumption of milk or dairy products did not show a proinflammatory effect in healthy subjects or individuals with metabolic abnormalities.
Milk and cancer myth
High intakes of dairy foods have often been associated with various forms of cancer, through some observational studies. These effectively show that people who eat more dairy foods, on average, are more likely to suffer from specific cancers. However, these studies only show that there is a relationship, and does not suggest that dairy causes cancer. Some studies also contradict one another, with some suggesting a protective effect of dairy, and others no relationship at all.
Self diagnosed allergies
Although it is clear that there are health conditions that are related to milk consumption it is also clear that self-reported rates of food allergy are much higher than the true prevalence.
For example, a population-based cohort study involving 3623 children found that 35% of parents perceived food reactions in their children (in reality this figure is around 2-10%). There are many tests being offered (see this blog on allergy testing) that will highlight milk and a number of other foods as causing allergies, but as we discussed before these tests are extremely unlikely to indicate any problem you may have with certain foods and can cause more harm than good. Unnecessary food avoidance could have unintended consequences, including nutritional deficiency. As we discussed inn a previous blog, there are many allergy tests on the market that are a waste on key and are likely
Milk provides the highest quality protein available and they do so in a nutrient-dense beverage that checks many boxes for athletes looking for recovery: rehydration, refuel, repair. As a ratio of money spent to benefits accrued, there are few beverages that challenge milk. Milk is, for the most part, a convenient, affordable recovery beverage. For those who are lactose intolerant, there are a wide range of low lactose alternatives. Lots of evidence shows milk is an effective recovery drink.
Prof Stuart Phillips
To conclude, milk is a great source of many nutrients both for health and sporting performance. Although some people may struggle with milk for specific reasons, this does not preclude everyone from enjoying its benefits.
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