In our last section I outlined the misconception that milk is not an appropriate human food. This belief is linked to the theory that we need time to have adapted to a food before it can be appropriately processed by our system and contribute to our health in a positive way. In this post I will continue addressing common arguments supporting the idea that milk is potentially unhealthy that, in my opinion, do not hold up to scrutiny.
Another common argument that dairy is “bad” is that populations which consume the most dairy have the highest rates of various epidemic diseases such as heart disease, obesity, and osteoporosis.
There are several recent studies that report that countries with the highest consumption of dairy also have the highest rates of modern chronic diseases, such as heart disease and osteoporosis (1). However, what is milk’s influence within smaller communities, where there is less variability than in large population-based observational studies? Let’s start by looking at the data available on studies correlating rates of milk consumption and these diseases in individuals within a single community. If milk is contributing to poor health, it would make sense that we would find that the individuals consuming the most milk would be at the highest risk for the development of heart disease, obesity, and osteoporosis.
So, what do studies measuring the specific effect of milk on individuals tell us? Thankfully, there are many studies looking at the nutritional value of individuals consuming milk in differing amounts, as well as studies showing its direct correlation with metabolic syndrome, obesity, and health of the heart and bones. In these studies, milk consumption is correlated with increased health by the markers used. So in the case of metabolic syndrome, which is considered a determinant of risk for all of the diseases mentioned, a meta-analysis published by the American Journal of Clinical Nutrition (2) found that “dairy consumption is inversely associated with the risk of having metabolic syndrome.” In other words, higher milk consumption is associated with lower rates of metabolic syndrome. As for cardiovascular disease specifically, in the Journal of Nutrition it has been reported that milk products positively affect the LDL profile of blood cholesterol (3). Additionally, the Journal of American Heart Association shows that the particles in the blood derived from the consumption of milk fat (mind you, as it is primarily saturated, it takes a lot for the AHA to say this), which are correlated with the highest rates of milk consumption, are associated with the lowest rates of cardiovascular disease (4). In a Welsh review of all cohort studies investigating the correlation of milk consumption with stroke and heart attack on “the basis of relevant biological mechanisms and data from ecological studies”(5), it was determined “that milk consumption may be associated with a small but worthwhile reduction in heart disease.” There is a tremendous amount of information on milk consumption and bone density, however it is primarily on women and children. In these studies, the consistent finding is that milk consumption has a positive effect on the immediate and long-term bone health of the women and children (6-10). A study of the bone health of milk-avoiders shows not only diminished bone health, but also shows an increased occurrence of obesity (10). Other studies on obesity have shown that those who consume more dairy are less likely to have unhealthy bodyweight for children (11), adolescents (12) and adults (13). So, these studies show the opposite correlation from that shown by the population-based studies referenced at the beginning of the post. These smaller, more controlled studies would suggest that perhaps milk consumption is good for us, rather than bad for us. In fact, this study published in the Journal of the American Medical Association in 2002 concluded that “Dietary patterns characterized by increased dairy consumption have a strong inverse association with IRS among overweight adults and may reduce risk of type 2 diabetes and cardiovascular disease.” (14)
So, why do we have directly opposite results from the population-based studies compared to these smaller, more controlled studies? What I believe is going on in the population-based studies is we are showing that the wealthiest and most industrialized countries also have the most access to dairy. These countries also have the most access to, and high consumption rates of, processed, prepared, and packaged foods. I believe it is more likely that consumption of these types of foods are responsible for the high rates of modern, Western diseases, such as metabolic syndrome and obesity. I also think that as these foods take the place of dairy for specific individuals within these communities, you will see the highest rates of those diseases. This theory is supported by the smaller population, more controlled studies presented earlier. By looking at consumption trends over time and analyzing the disease rates in the same community, the evidence better supports that the consumption of processed foods, and not dairy, is more likely the attributable dietary factor in increased prevalence of disease. This hypothesis is in no way proven, and it is likely it never will be. In a well-conducted meta-analysis of the relevant available data regarding the relationship between dairy consumption, disease and mortality, dairy consumption was associated with a decreased prevalence of disease and a reduction in all-cause mortality. However, the authors clearly outline the limitations of the available studies conducted to date (15). Specifically, the authors explained that due to the numbers of subjects and controls needed for robust statistical analysis, it is unlikely a comprehensive study in humans will ever be performed. However, my hypothesis as to the relationship between processed foods and dairy is supported by the consumption rates in Americans (16). When looking at the trend for milk consumption on average by demographic, the obese individuals of any demographic are consuming the least dairy (17). As the disease rate went up, the consumption of dairy went down, and simultaneously the consumption of processed food and food additives went up. I do not offer this as proof. I just want to show support for the idea that the high rate of chronic disease in America and the high rate of dairy consumption is probably coincidental.
To plant a seed of hope, we must look for an example of a community that has a high rate of dairy consumption and does not have a high rate of disease. When studying small communities, the likelihood of coincidental correlations due to a misrepresentation of the actual behaviors and correlations within the community is reduced. This is partially due to the fact that small communities are in many ways more homogenous than larger communities. For example, when looking at traditional pastoral communities and their rates of disease, it is much safer to assume you are measuring the incidence of disease in people who are actually consuming a lot of dairy relative to other communities. This is still not controlled in a way that shows causality, but it gives us a more accurate account of whether communities consuming high levels of dairy have high levels of disease.
When studying traditional pastoral cultures that have dairy as a major source of nutrition, it becomes obvious that the epidemic diseases plaguing modern societies within these communities is very low. One of the most frequently mentioned examples of such communities are The Masai warriors, a group cattle herders in Northern Africa. The Masai consume tremendous amounts of high-fat dairy, in addition to the other foods which they gather, such as a fibrous roots and honey. Their diet is also supplemented with fruits, vegetables, grains, and other items that more industrialized communities produce such as sugar, flour and oil via trade with outside communities. Of particular interest is a group of men of the Masai tribe who are often cited as an example of the health benefits of milk. In the early 20th century, the entire community underwent extensive observation by an anthropologist. In the study, the anthropologist observes that the Masai men are in extremely good head and are free of disease, even into old age, despite a lifestyle that involves significant hardship. The men, who are referred to as the Warriors, became the subject of fascination for a ceremonial rite of passage that takes place between the ages of 13 and 30 in which they only consume milk that has been mixed with blood of the cow. This rite of passage has fascinated many who are interested in the health affects of this sort of fiber-free, high-saturated fat diet. Interestingly, these men, even after the age of 50, are essentially free of all the diseases considered to be modern epidemics. Chris Master John has the best analysis of the available information on the Masai I have found yet, and he well outlines the good health of the community and complexities surrounding their way of life (18). However, I do not want to use these Masai warrior men as a sole display of a healthy community with a high consumption of milk. I am not unaware that their stressful life has significantly lowered their life expectancy to somewhere around 60 years old. Often they are fortunate to be able to first reach the age which initiates the period of time with the blood milk only diet. It is also the case that these men’s unique lifestyle takes a toll on their body and this can confound the data as to what role their diet plays (19). Still, it is the case that they are NOT obese, fragile individuals at risk for suffering heart attacks(20) in spite of their incredibly high consumption of dairy. However, just because these people consume a lot of milk and are in good health, we cannot assume that milk is the sole or major reason for their good health. There are many other factors that probably also contribute to their health. With that in mind, let’s explore some other cultures which have inordinately long life expectancies, different lifestyles, yet are similar in that they have high rates of dairy consumption. Perhaps this can shed further light on the relationship between milk consumption and good health.
Another example of modern day pastoral communities are the shepherding communities in the northern mountains of Sardinia. Sardinia is an island located off the coast of Italy where low rates of heart disease and a long life are celebrated as exceptional within the international context, deeming it the first recognized “Blue Zone” (21), a term that has been developed in order to refer to an area with an inordinately high life expectancy. In Sardinia, cheese is a highly acclaimed feature of the diet on the island. The highest concentration of long-lived individuals is in the shepherding communities, which are said to consume the most milk and cheese (22). Another long-lived community lives in the country of Azerbaijan, located at the crossroads of Europe and Asia. Once again we find that the individuals who live the longest have a high level of dairy consumption, primarily as fermented whole goat’s milk, fresh milk, and cheese to a lesser degree (23,24). These examples of healthy, long-lived communities that consume high amounts of dairy supports the finding of potential benefit from increased dairy consumption noted in the controlled clinical studies cited earlier. However, the variables in all of these studies are not well controlled with respect to physical activity, psychosocial stress, and climate. Still, from these three examples of traditional milk drinking, healthy cultures, we do see a variety of climates with good health and dairy consumption being one thing that is similar in all three.
It is my belief that these examples suggest that milk can be a major component in the diet of healthy communities. However, because the data in the studies and the social observation I have presented does not control all variables, they cannot actually prove without a doubt that milk is a contributor to the health of these communities. In order to explore this possibility, in a future post in this series I will be outlining some data and possible mechanisms on how milk may in fact be contributing to a healthy, disease-free state.
In my next post, Part III of the series on Dairy, I will be discussing the potential that our current milk is in fact too toxic to consume in comparison to alternative sources of nutrition due to the modern agricultural practices prevailing in the dairy industry.
Resources:
(1) Countries with highest dairy consumption have highest rates of osteoporosis
http://m.ajcn.nutrition.org/content/89/5/1638S.full
(2) Meta-analysis of coralation with metabolic syndrome
http://m.ajcn.nutrition.org/content/82/3/523.full
(3) Milk products positively effect ldl particle size ratios
http://jn.nutrition.org/content/134/7/1729.long
(4) Journal of american heart association shows that specific fatty acids may be a good biomarker of dairy intake and that these are correlated with resistance to CVD
http://jaha.ahajournals.org/content/2/4/e000393.full.pdf
(5) Men who drink milk have less heart attack and strokes
http://www.ncbi.nlm.nih.gov/m/pubmed/15116074/?i=2&from=/15116073/related
(6) Lifetime milk consumption and bone health in women
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1615461/
(7) Larger study showing correlation of low milk consumption as a child and increased fracture risk in adult women
http://www.ncbi.nlm.nih.gov/pubmed/12499350
(8) Same in korean women
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3746166/
(9) Poor bone health in children who don’t drink milk
http://www.ncbi.nlm.nih.gov/m/pubmed/12198017/
(10) Children who don’t drink milk have more fractures
http://www.ncbi.nlm.nih.gov/m/pubmed/14760576/
(11) Obesity and bone health in milk avoiders after two year follow up
http://www.ncbi.nlm.nih.gov/m/pubmed/15565350/?i=2&from=/12198017/related
(12) British study of milk consumption in children inversley related to obesity
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=917384
(13) Small study of girls 9-13yrs old and association of various factors and illiac skin fold thickness milk calcium specifically well correlated and non dairy calcium not well correlated
http://jn.nutrition.org/content/134/8/1905.abstract?ijkey=36ccfadbdc503d1f012a687ef4d65b50cdd47e23&keytype2=tf_ipsecsha
(14) Dairy consumption inversely related to Insulin resistance and obesity
http://www.ncbi.nlm.nih.gov/pubmed/11966382
full text:
http://jama.jamanetwork.com/article.aspx?articleid=194858
(15) Meta analysis of dairy consumption and disease ratios based on individual consumption talks about the need for a large long term study which will probably never happen.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2950929/
(16) Food consumption in america table 2-1 and 2-2
http://www.usda.gov/factbook/chapter2.pdf
(17) Dairy consumption by demographic the more over weight the less dairy they are consuming
http://www.ers.usda.gov/datafiles/Commodity_Consumption_by_Population_Characteristics/Food_Intakes_Converted_to_Retail_Commodities_Database/ficrcd_dairy.xls
(18) Maasai Overview by Chris Masterjohn
http://www.westonaprice.org/blogs/cmasterjohn/2011/09/13/the-masai-part-ii-a-glimpse-of-the-masai-diet-at-the-turn-of-the-20th-century-a-land-of-milk-and-honey-bananas-from-afar/
(19) Part iii of Masterjohn Maasai series addressing disease and life span in the masai
http://www.westonaprice.org/blogs/cmasterjohn/2012/06/04/the-maasai-an-interlude-what-does-all-this-sociocultural-and-historical-stuff-have-to-do-with-heart-disease/
(20) Maasai low heart disease in spite of high fat content
http://m.bjsm.bmj.com/content/early/2008/06/03/bjsm.2007.044966.abstract
(21) Sardinia people low heart disease high longevity
http://en.wikipedia.org/wiki/Sardinian_people
(22) The highest density of long lived individuals is in the shepherding portion. The pdf is primarily concerned with the activity levels between the communities but it does mention the increased cheese consumption.
http://www.ncbi.nlm.nih.gov/pubmed/21958760
(23) The long lived individuals in Azerbaijan specific diet characteristics
http://www.ncbi.nlm.nih.gov/m/pubmed/1830710/
(24) Article on the long lived in Azerbaijan
http://www.azer.com/aiweb/categories/magazine/23_folder/23_articles/23_centenarians.html
