Although the health community mostly defends the glass of milk as an example and good practice of a healthy diet and nutritional quality (for example with campaigns such as Get the Glass), the milk and dairy is a food group harshly punished by the new nutritional trends. The lactose intolerance of a good part of human beings has contributed to reinforce this black legend. Or books like "Your life in your hands", written by geochemistry teacher Jane Plant, have fanned the flames against them, as the author thinks she was cured of breast cancer by stopping drinking milk and dairy products.
Also the latest trends in the so-called paleolithic diets, especially those more in line with Loren Cordain's guidelines, restrict them significantly, since according to these approaches did not appear in the diet of our ancestors. This argument is usually reinforced by the possible presence of antibiotics or hormones that industry uses on livestock (something that can really be a problem) and by the supposed nutritional degradation that occurs during pasteurization. Specifically, this process in which the product is heated to high temperatures for a very short time in order to eliminate microorganisms, is one of the most criticized, being blamed for a good number of drawbacks that, according to some, surpass its more than interesting sterilizing efficiency.
As you can imagine, for a server the argument "we are the only animal that continues to drink adult milk" is not enough. We are the only animal that does many things, without having to be bad or negative because of it. Although some of the advocates of these anti-dairy theories propose different mechanisms and studies to justify them, the most direct way we have to check if all these fears really make any sense is through epidemiological studies. If dairy products cause breast cancer, we will find a higher prevalence of this disease among women who consume it in greater quantity. Or if its intake affects the cells of our pancreas, the increased incidence of diabetes will also be evident.
Fortunately, extensive reviews and meta-analyses have recently been published on the subject, so we won't have to go study by study because many experts have done so before:
- A systematic review and meta-analysis of the effects of pasteurization on milk vitamins, and evidence for raw milk consumption and other health-related outcomes was published in 2011, in which it was concluded that although the process causes some decrease in the concentration of some vitamins, they are not many nor is it a particularly important reduction. Regarding the consumption of raw milk, the review did not identify solid studies that found neither clear advantages nor disadvantages.
- The publication of "Unpasteurized Milk: A Continued Public Health Threat" (2009) also highlighted the large number of risks involved in consuming unpasteurized milk and the lack of scientific evidence regarding the accusations of nutrient loss after this process. The following table included described in detail how little various nutrients were affected.
- In 2011 the meta-analysis "Dairy consumption and risk of breast cancer: a meta-analysis of prospective cohort studies" was published, reviewing studies on breast and dairy cancer and concluded that higher consumption correlates with lower incidence of this type of cancer (inverse relationship).
- In 2012 in the meta-analysis "Dairy products and colorectal cancer risk: a systematic review and meta-analysis of cohort studies" the researchers also concluded that a higher total consumption of dairy and milk was associated with a lower rate of colorectal cancer. The 2004 study "Dairy foods, calcium, and colorectal cancer: a pooled analysis of 10 cohort studies" reached similar conclusions.
The 2008 meta-analysis "Dairy products, dietary calcium and vitamin D intake as risk factors for prostate cancer: a meta-analysis of 26,769 cases from 45 observational studies" also found no correlation between dairy consumption and prostate cancer. On the other hand, the global review Evaluating the links between intake of milk/dairy products and cancer published in 2012 analyzed the studies that have investigated during the last years the relationship between dairy and cancers of the gallbladder, prostate, breast and colon. The authors found no clear evidence of any association with prostate cancer and found an inverse relationship (more dairy - less cancer) in the rest.
- The research "Milk and dairy consumption and risk of bladder cancer: a meta-analysis" (2011) found no solid scientific evidence associating the consumption of milk or dairy products with gallbladder cancer.
- In the 2009 article "Milk products, insulin resistance syndrome and type 2 diabetes" the inverse correlation (more dairy - less diabetes) between dairy consumption and diabetes and the metabolic syndrome was highlighted and references from studies confirming this were included. Similar conclusions were reached in the 2010 review "The consumption of milk and dairy foods and the incidence of vascular disease and diabetes: an overview of the evidence".
- Similarly, in the 2012 review of which we spoke in an earlier article "The relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease" in the different included studies no relationship was found between dairy and diabetes, or the one found was an inverse relationship.
Mortality and Other Diseases
- These are the meta-analyses on cardiovascular diseases, all of them with favourable or neutral results for dairy products:
- "Dairy consumption and CVD: a systematic review and meta-analysis" (2016)
- "Dairy consumption and risk of cardiovascular disease: an updated meta-analysis of prospective cohort studies" (2015)
- "Dairy foods and risk of stroke: a meta-analysis of prospective cohort studies" (2014)
- "The relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease" (2013)
- "Milk and dairy consumption and incidence of cardiovascular diseases and all-cause mortality: dose-response meta-analysis of prospective cohort studies" (2011)
- The review A systematic review and meta-analysis of elevated blood pressure and consumption of dairy foods" (2012) concluded that higher consumption of skimmed dairy products is associated with lower blood pressure and that whole dairy products have no association with this pathology.
- The 2008 meta-analysis "The survival advantage of milk and dairy consumption: an overview of evidence from cohort studies of vascular diseases, diabetes and cancer" analyzing studies that investigated the correlation between dairy and mortality in relation to cardiovascular disease, diabetes and cancer, concluded that there is a correlation between increased survival and increased dairy intake.
Conclusion: Dairy products are associated with better health and lower mortality
It seems to me that the evidence is strong. If you do not have any kind of intolerance, dairy and milk do not seem to be bad at all, quite the contrary, your usual consumption has a lot of benefits and the most reasonable decision is to take them after pasteurization. The hypotheses and theories against them may be interesting or sound good, but for the moment the epidemiology contradicts them categorically.
However, drink milk, cheese and yogurt as naturally as possible and avoid added sugars and high processing, which result in products more similar to soft drinks or sweets than real food. A drinkable one of those given to children at snack time is much less recommended than a normal glass of milk. And even a glass of water.
It is true that much of the research on dairy products has been funded by industry, but there are also many independent studies and the review "Relationship between funding sources and outcomes of obesity-related research" (2012) found no evidence that there were differences between the results depending on their funding.