Written by: Nikolaj Bach, BCs. Scient. Med.
"Milk from cows is unhealthy and you should not drink it."
"We are the only mammal on earth that drinks milk after we have reached adulthood. And sign up for milk that is not our own, but from a cow whose sole purpose is to get his offspring to gain 200kg in weight in a very short time. It's downright idiotic. "
"When I stopped, my glass ankles, which were always wiggling to football [...]" disappeared.
This is how radio host and media celebrity Peter Falktoft wrote earlier this year on his Facebook profile. From Cand.Scient. Morten Elsøe subsequently asked him to substantiate his claims with scientific literature, and also referred to studies that contradicted Falktoft, so it was met by a response that can only be described as deeply childish and involuntarily comic. It was quite clear that Peter felt attacked by his identity, rather than his arguments. It is a very normal reaction when one's attitudes are challenged, if it is about a topic that one is emotionally invested in. When one bases one's assessments on feelings and opinions instead of facts, then one takes the criticism very personally, because the topic has emotional meaning for one.
This should not be the case at all, because the scientific approach is not about getting it right, but about arriving at the truth - and that means being willing to change one's judgment, by virtue of new knowledge or convincing arguments. Yet, in this age and age, it is becoming more and more common to base one's view of health on statements made by random celebrities rather than professionals, and feelings and opinions are increasingly accepted as valid facts.
Here one could also talk about anti-vaccination movements, alternative medicine, or gluten, but the topic of this article is milk. And milk in particular is something that many have strong opinions about. Milk has been accused of being carcinogenic, associated with a higher mortality rate, and causing osteoporosis.
Conversely, there are also market forces that describe milk as being unconditionally healthy (for example, the slogan in the campaign "Milk is for life" is quite value-laden).
But the data is what they are. And there are some who have looked at them. More specifically, Thorning et al., Who in a new Danish literature study have made a very comprehensive review of the available research, regarding the importance of dairy products for health. And this review is just the starting point for this article. It is entitled “Milk and dairy products: good or bad for human health? An assessment of the totality of scientific evidence ”and is published in Food & Nutrition Research (1).
Milk, obesity and diabetes
Obesity is a very significant risk factor in developing type 2 diabetes. Therefore, the authors looked at studies that had examined the association between intake of dairy products and obesity.
A meta-analysis showed that there was no correlation between the intake of dairy products and the prevalence of obesity in children, and the intake was in fact associated with a reduced risk of obesity in adolescents (2). And a recent meta-analysis even showed that the children who had a high intake of dairy products had a 38% lower risk of developing obesity than the children who consumed the fewest dairy products (3).
So it does not seem that consuming dairy products leads to obesity. However, this is not the same as saying that milk protects against obesity, or that milk is the cause of the lower risk - just that there is a correlation. Nevertheless, the researchers in the review come up with a suggestion of the connection: Dairy products have a high content of protein , which has a satiating effect, and this can help prevent an excessive intake of calories. The essential amino acids found in high-quality proteins are also important for the maintenance of muscle mass during weight loss, and the researchers thus speculate that quality protein from dairy products can help maintain the metabolically active muscle mass, and thereby healthy weight regulation (1).
If you look at the connection between dairy products and diabetes specifically, then several meta-analyzes have not shown any increased risk. On the contrary, the most recent meta-analysis of 22 studies and 579,832 individuals, including 43,118 diabetics, found that consuming dairy products (especially yogurt, but not milk) was associated with a reduced risk of developing type 2 diabetes (4). Again, this does not mean that there is a direct causal link, but the authors suggest that the fermented dairy products, such as yoghurt and cheese, may have a beneficial effect on the intestinal flora that may be important for the development of diabetes (1):
Milk and cardiovascular disease
It has been speculated whether the saturated fat in fatty dairy products such as cheese should lead to an increased risk of cardiovascular disease. However, that does not seem to be the case. Where low-fat, high-calcium dairy products have been associated with a lower risk of high blood pressure (5), fatty cheeses do not appear to increase blood LDL cholesterol levels to the extent that one would expect, contrary to butter (6). On the one hand, this suggests that the particle size of LDL cholesterol is important, where the larger LDL particles in milk and cheese appear to be less risky in relation to atherosclerosis, and on the other hand, the minerals in milk and dairy products may counteract a high fat intake effect on LDL -cholesterol level (7-9).
Several studies have not found any increased risk of cardiovascular disease when consuming dairy products, or have even shown a reduced risk (10-15). In fact, a new meta-analysis of as many as 31 studies found that consuming dairy products was associated with a 9% lower risk of stroke, with cheese specifically being associated with a 13% lower risk of stroke and an 8% lower risk of coronary heart disease (16).
The researchers conclude that an intake of 200-300 ml of dairy products per. today does not increase the risk of cardiovascular disease, and may be associated with a lower risk of stroke and high blood pressure (1). In continuation of this point, it is important to mention that health-conscious people are generally inclined to consume dairy products, especially those with a low fat content, and that this may have an effect on the results (17) - and the reduction in risks is not necessarily due to intake of milk specifically, but can also be influenced by a healthier lifestyle in the people who consume dairy products.
Dairy products have a high content of protein, which has a satiating effect and can help prevent an excessive intake of calories.
Milk and osteoporosis
Some of the milk is often blamed for causing osteoporosis, osteoporosis. "Just look at how many people in Scandinavia get osteoporosis, and we drink a lot of milk!" Paradoxically, dairy products contain significant amounts of all the substances that are important for building bone tissue - including protein, calcium, phosphorus, magnesium, and vitamin K - with the exception of vitamin D (1). Maybe the bone growth in the north suffers from not getting enough sun and vitamin D rather than drinking milk?
A meta-analysis found that supplementation with dairy products, both without and in combination with vitamin D, was associated with an increase in bone mineral content in children who had a low intake of dairy products - but not in those children who already had a higher intake of these (18). On the other hand, it has been more difficult to demonstrate any positive effect in adults. Thus, two meta-analyzes have not shown a reducing effect on the risk of developing osteoporosis in adulthood (19,20).
Against this background, the authors of the new review conclude that there is a positive correlation between milk and dairy products, and the bone health of children and adolescents. On the other hand, the evidence for a preventive effect on bone fractures in adulthood is deficient, just as it is not clear whether the dairy products in that case must be enriched with vitamin D (1).
Milk and cancer
The new review also examines whether there are any correlations between milk intake and the development of different types of cancer. The literature in this area is motley and deficient, but the researchers conclude that consuming dairy products is probably associated with a lower risk of colorectal cancer (21-23), breast cancer (24,25), bladder cancer (22,26), and stomach cancer (27) . On the other hand, they speculate that a high intake of dairy products may increase the risk of developing prostate cancer (28,29), but that the evidence is not uniform. In addition, however, they conclude that a possible effect on prostate cancer is outweighed by the lower risk of colorectal cancer, which is associated with an intake of dairy products (1).
The fact that the consumption of dairy products may be associated with a lower risk of certain cancers is not the same as the fact that it is a causal relationship, where milk necessarily prevents these. But in any case, there is no evidence to suggest that milk in general should be carcinogenic. The Danish Cancer Society writes that milk at present can neither be discouraged nor recommended in relation to cancer risk, and that there is no convincing connection between milk and cancer when looking at the population surveys as a whole. For prostate cancer, they write: “There is a possible link between a high intake of milk and the development of prostate cancer. This may be due to the fact that a diet high in calcium may increase the risk of prostate cancer ”(30)
Based on the evidence, the answer to whether milk is unhealthy is quite clear. No.
Milk and mortality
Of course, we do not get around to talking about mortality. Does milk increase your overall risk of dying on your glass ankles?
In any case, it is not something that is supported by the overall evidence. Thus, a meta-analysis found no correlation between the saturated fat from dairy products and mortality (31). The most recent meta-analysis of 12 epidemiological studies also showed no association between intake of dairy products and overall mortality, or mortality due to cardiovascular disease or cancer (32). Here it is relevant to mention that the lead author of this meta-analysis also helped to carry out the only epidemiological study that has found an increased mortality from a high milk intake - about which has since been criticized, among other things because there was a difference in caloric intake between groups (33).
So the conspiratorial argument about corrupt researchers does not hold. Nor does it now in general, if it is one's first instinct, when one sees data that contradicts one's own perception. Then it is instead an expression that you do not want to relate to evidence other than the one that confirms your own point of view. But other words lead to such an attitude that you create an echo chamber around yourself, in which you only hear your own voice.
"All things are poison and nothing is without poison; only the dose makes a thing not a poison."
This is what the father of toxicology, Paracelsus, said back in the 16th century. Since then, we have acquired an enormous amount of knowledge, but we have apparently not become much wiser. At least not if we base our views on what is healthy and unhealthy on unsubstantiated postulates from radio hosts and celebrities. It is like asking your plumber for advice about your infection, or calling your doctor because your car needs to be repaired.
Based on the evidence, the answer to whether milk is unhealthy is quite clear. No. This is not to say that it cannot be dispensed with or that it is unhealthy to avoid dairy products. It's all about the overall diet and how it's screwed up. Nevertheless, the researchers in the new review estimate that it would potentially have a negative health effect at the population level if people were discouraged from consuming dairy products - their conclusions regarding diabetes, cardiovascular disease, and obesity in mind (1).
In other words: If you love squats and milk, then luckily you do not have to do without any of them.
The scientific approach is not about getting it right, but about reaching the truth
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