When I began to delve into the human relationship with dairy products I was astonished at the far-reaching effects of eating these foods. Human milk is, without a doubt, the optimal food to feed a human baby for the healthiest start in life. Other mammals, like bovines (cattle, buffalo, yaks, antelopes), also produce milk for their babies. In the case of cattle, their milk has the requirement to support the fastest growth possible for their offspring in order to reduce the young animal’s vulnerability to predators and ensure that successful reproduction will take place, a genetic goal for every species of living being. The milk of each species of mammal is tailored to their specific needs. So drinking the milk of another species may not be the best idea. And scientific investigation is increasingly revealing that consuming dairy food beyond childhood from any source is unwise.
As people of this day and age, we have grown up with the belief that milk is one of the healthiest of foods and we might even go so far as to consider cow’s milk necessary for us to thrive. The media message that milk consumption is crucial for human well-being is extremely strong, so much so that it has become entrenched in our psyche. Programs such as the Elementary School Milk Programs across Canada administered by Dairy Farmers of Canada (with similar programs present in many other countries as well) lend credence to the overall healthy aura surrounding milk. We are told that milk is the ideal source of the calcium that we need, not only for thriving as babies but also to produce and maintain the strong bones we count on to carry us through life. Unfortunately this message is far from the truth. In fact, there are many alternate foods that can supply all the beneficial nutrients of milk without its accompanying potential harmful effects.
Previous to the mid-1900s Canadians consumed only a very small amount of milk. The advent of Canada’s first food guide in 1942, with milk included as a food group along with advertising by milk producers, was the catalyst that began the rise in consumption of dairy products for Canadians (1). By the 1970s we were consuming an average of 110 liters of milk per person per year (2). Milk consumption remained around this high level for a decade or so but eventually various factors led to a slow decrease. In 1995 average per person yearly consumption was 90 liters; by 2004 it had lowered to 86 liters; and 2017 found per person milk consumption down to slightly less than 70 liters. Some of this decrease can be attributed to the rising ethnicity in Canada over these years with new Canadians continuing to follow their traditional habits of low or no milk consumption (3,4).
In contrast, cheese consumption has increased dramatically over the last few decades. Canadians ate very little cheese during the 1950s but consumption soon began to rise, becoming 5 kg per person per year in 1976, 11.5 kg in 1998 and 15 kg in 2016. This increase in cheese consumption continues still and shows no signs of stopping (5,6). Similar situations have occurred in the US with per capita yearly cheese consumption of 3 kg in 1950 increasing to 15 kg in 2017 (7,8). Trends around the world echo this situation. For instance, per capita per year cheese consumption in Italy grew from about 7 kg in 1960 to 23 kg in 2013 while the French went from 9 kg in 1960 to 24 kg of cheese per person per year in 2013 (8,9).
Of course, our earliest ancestors did not consume dairy foods at all. It was about 7,500 years ago that humans first domesticated cattle (10) and a good while after that before increasing numbers of us began to retain into adulthood the enzyme lactase that is needed to digest lactose, the sugar in milk, making its ingestion a more comfortable experience (11). Our actual consumption of cow’s milk has accompanied only a small part of our evolution as human beings. New research on genome sequences estimates that humans and gorillas diverged into two distinct species 15.1 million years ago while humans and chimpanzees went their separate ways 12.1 million years ago (12). Research on ancient DNA indicates that modern humans, Homo sapiens, have existed for somewhere between 250,000 and 360,000 years (13).
Much more recently, nutritional research has discovered associations between eating dairy products and numerous health issues. Milk and other dairy foods are loaded with fats, animal proteins, lactose and galactose, hormones and environmental contaminants to name a few of its ingredients with the potential to harm humans. This article is the first of a series that will examine possible health problems for those who partake of dairy products.
10 Bollongino, R., Burger, J., Powell, A., Mashkour, M., Vigne, J.-D., Thomas, M.G. Modern Taurine Cattle descended from small number of Near-Eastern founders. Molecular Biology and Evolution, 2012.
11 Itan, Y., Powell, A., Beaumont, M.A., Burger, J., Thomas, M.G. The Origins of Lactase Persistence in Europe. PLoS Computational Biology, 2009; 5 (8): e1000491.
12 Schlebusch, C.M., Malmström, H., Günther, T., Sjödin, P. et al. Southern African ancient genomes estimate modern human divergence to 350,000 to 260,000 years ago. Science. Nov 3, 2017; 358(6363): 652-655.
13 Moorjani, P., Amorim, C.E.G., Arndt, P.F., Przeworski, M. Variation in the molecular clock of primates. Proceedings of the National Academy of Sciences. 2016; 113 (38): 10607–10612.