Milk as a risk factor for vascular dysfunction
One of my favorite bloggers, Paul Whiteley, has highlighted a paper that shows that significant milk consumption can have some major downsides for health. See the paper here: http://www.bmj.com/content/349/bmj.g6015. See Paul’s masterful discussion of it here: http://questioning-answers.blogspot.com/2014/11/milk-has-gotta-lotta-bottle.html.
The authors find a link between milk consumption and the elevations in markers for vascular damage, the elevation of cytokine IL-6, and the increases in mortality. The propose that this is due to the D-galactose content of milk. An viable explanation is the vitamin D content of milk. I originally made a comment on this on Paul’s blog that he graciously posted. I provide it here as well:
This is another fascinating paper that you have highlighted. I completely agree with you that higher IL-6 is worthy of exploration. It is interesting that the elevations were more common in males and that males were more likely to suffer increased mortality from milk intake.
I have an alternative interpretation of the authors’ findings which I think are more compelling. I understand the subjects in the study were Swedish adults. Sweden may have the highest level of oral vitamin D consumption of any European country. See: http://journals.cambridge.org/download.php?file=%2FPNS%2FPNS62_04%2FS0029665103001071a.pdf&code=7875fc995d2e69bd559d97c60a9e146d. A big part of this is the vitamin D in fortified milk and milk products.
At very high doses oral vitamin D is known to promote vascular calcification. In addition there are hints of negative effects on serum lipids in some populations based on more modest supplementation. See:http://www.ncbi.nlm.nih.gov/pubmed/9405029. Interestingly it is more toxic in large doses to males than females (at least in rat studies):http://www.toxicologyinternational.com/article.asp?issn=0971-6580;year=2008;volume=15;issue=2;spage=143;epage=144;aulast=Kaur
Also oral vitamin D supplementation has been shown in some diseases to upregulate IL-6. See: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2036.2010.04463.x/pdf. I should acknowledge that this was taken to be a positive effect by the authors of this study.
In any case what this data suggests to me is that Sweden has high levels of vitamin D supplementation already and raising them further by significant consumption of vitamin D fortified milk may be leading to dysfunctional upregulation of IL-6 production in some. I suggest that this effect is most prominent in males as observed and this is a factor in the modest increases in markers for vascular damage and increased mortality that is most prominent among males.
Taking this a bit further what other populations receive large doses of supplemental vitamin D? It turns out in most developed countries many infants and toddlers receive huge amounts of oral vitamin D relative to their weight and their size: much more than adults consume based on their weight and size. Are there any conditions that feature elevations in IL-6, elevations in markers for vascular damage, and that affects male children disproportionately? As you among others have pointed out autism is such a condition. See here:http://www.ncbi.nlm.nih.gov/pubmed/23994594.
Going back to Sweden public health officials began recommending vitamin D supplementation in infancy for all infants using vitamin D drops starting in 1978:http://journals.co-action.net/index.php/fnr/article/viewArticle/1632. And what was the effect of this on the autism incidence in Sweden? I don’t think there is good data on Sweden as a whole for this time period but there is solid data on the Goteborg area in Sweden thanks to work by Gillberg et al. They found that there was a 110% rise in autism diagnoses between birth years 1978 and 1979. See:http://www.ncbi.nlm.nih.gov/pubmed/16568356. Oral vitamin D supplementation among the young is a risk factor for autism. Unfortunately most people don’t realize this yet.