Milk consumption – have we been misinformed?
From early childhood on we are made to believe that the more milk we drink the stronger our bones will become. We get bombarded with this message from every direction; in school, on posters, in ads and from our parents. Now more and more research is showing that actually the opposite could be true; that the more milk we drink the weaker our bones become. It was more than 25 years ago that I first read about milk not being as healthy as it was promoted to be. Unfortunately I didn’t keep track of the research that I came across at that time but I remember that some of them suggested that drinking milk changed the acidity of the blood causing calcium to be leached from the bones. Looking at the literature today I stumbled upon research like the one that was performed in 1994 in Sidney Australia and looked at elderly men and women showing that higher dairy product consumption was associated with up to double increased fracture risk. Similar findings were confirmed by Karl Michaëlsson, a lead researcher at Uppsala University in Sweden, who along with his associates published a study in BMJ in October 2014. The study looked at two large Swedish cohorts who were administered food frequency questionnaires. The results showed that high milk intake was associated with higher mortality in one cohort of women and in another cohort of men, and with higher fracture incidence in women.
How can milk consumption lead to fractures and shortened lifespan?
The Swedish authors speculate if high intake of milk might have undesirable effect because it is the main dietary source of D-galactose. Milk contains essential nutrients such as calcium, phosphorus, and vitamin D whose intestinal uptake is enhanced by the enzymatic capacity to digest lactose into D-glucose and D-galactose by mutation in the lactase gene, a variant common in those with northern European ancestry. Experimental evidence in several animal species indicates that chronic exposure to D-galactose has deleterious effects on health inducing changes that resemble natural aging in animals, including shortened life span. This is caused by oxidative stress damage, chronic inflammation, neurodegeneration, decreased immune response, and gene transcriptional changes. The increase of oxidative stress with aging and chronic low grade inflammation has been connected to cardiovascular disease and cancer in humans as well as being mentioned as a possible mechanism of age related bone loss.
It could also be mentioned here that the Physicians Committee that combines the expertise of more than 12,000 physicians points out that ecological studies suggest higher mortality rates from fracture and ischaemic heart disease in countries with high milk consumption.
I don’t know about you but after reading about these studies I feel kind of funny when I see the ads recommending increased milk intake for prevention of fractures and improved health.
Is cheese and yogurt ok?
There is one thing that we can be glad about though i.e. the fact that the Swedish research showed that consuming cheese or fermented milk products like yogurt seemed to have the opposite effect of drinking milk. Thus women with a high intake of cheese or fermented milk products had lower mortality and fracture rates than women who consumed less of the same.