The Cows-Milk Calcium Connection – Challenging Traditional Minds

drip-175551_1920

Here in the UK, we collectively purchase around 5.2 billion litres of liquid cow’s milk from the supermarkets and milkman each year (1) – that’s roughly 75 litres of milk per year, per person, if we are including all 70 million of us.  On top of that, 6,072 million litres go towards dairy products such as cheese, butter and dried milk powder (1) – staple components of many favourite dishes and traditional home-comfort foods.

Like the majority of people born and raised in the UK, I was raised to believe that cow’s milk was a nutritious source of vital micronutrients such as calcium, vitamin D and the B-vitamin complex – calcium in particular, has enjoyed a long and fruitful reign as the sole beneficiary of cow’s milk.

Now, we already know that calcium is an essential and obligatory micronutrient – it’s the most abundant mineral in the human body (2), and is responsible for numerous biological functions including bone density maintenance, cell-signalling and regulation of protein function (2). Calcium is vital to our well-being, and we must safeguard calcium stores through sustained consumption of calcium-rich foods, or risk some major negative health outcomes. (The average* adult should be consuming approximately 1000mg per day, in case you were wondering).

It’s great to see the emergence of research papers that strike against popular belief, and open-up the minds of those who are willing. Traditional thinkers will know that cow’s milk and its derived products such as yogurt and milk, have long been recommended as excellent sources of calcium that have the potential to maintain bone density and aid growth during childhood. However, increasing evidence is beginning to emerge in regards to the cow’s milk-calcium connection, and the results aren’t what popular culture would have us believe…

A study published in the British Medical Journal in October 2015 examined whether high cow’s milk consumption was associated with mortality and fractures in both women and men, and found 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.

Because of the high content of lactose in milk, the researchers hypothesised that high consumption of milk may increase oxidative stress, which in turn affects the risk of mortality and fracture. The paper notes that a high intake of milk might, however, have undesirable effects, because milk is the main dietary source of D-galactose. Even a low dose of D-galactose induces changes that resemble natural aging in animals, including shortened life span caused by oxidative stress damage, chronic inflammation, neurodegeneration, decreased immune response, and gene transcriptional change.

You can read the full article here: http://www.bmj.com/content/349/bmj.g6015

I think this article highlights the importance of having an open mind, as a human sciences student or consumer in general, as traditional teachings may not always provide a complete answer. A cautious interpretation of the results in this paper were recommended, however there are many studies elsewhere that support similar claims – wider reading is certainly recommended.

The shift in attitude towards food products, especially contentious ones such as animal products (meat, dairy and eggs), superfoods and health-related supplements is especially fascinating – and an area I am keen to keep an eye one. I would encourage anyone with an interest in nutrition to do the same, it speaks volumes about societies incentives and values.

All in all, the UK buys enough dairy products fill nearly 4,500 Olympic-size swimming pools every year – but, is it really doing us any good?

Charlotte Harbour – 2nd Year Nutrition Student

*Average is depicted as an 18 years + male or female with a healthy/normal body fat percentage and no chronic disease or health implications that would influence or dictate calcium absorption and/or consumption.

**(Immunoglobulin G (IgG), the most abundant type of antibody, is found in all body fluids and protects against bacterial and viral infections)

(1) http://www.thisisdairyfarming.com/discover/dairy-farming-facts/how-much-milk-do-we-drink-in-the-uk/

(2) http://lpi.oregonstate.edu/mic/minerals/calcium

DISCLAIMER – this article is intended for information only and should not be considered to be nutritional advice. If you would like to change your diet please see a qualified registered practitioner for professional advice.

Advertisements

One comment

  1. This is such a useful article – personally I find the data on milk consumption so contrary and so much published by the large Dairy Unions! Personally I try to drink less milk – that is to say I love milk in a cup of tea and a latte is a once a week treat, but I would choose almond milk for soaking oats for breakfast.

    Both the Eatwell Plate in the UK and the US MyPlate recommendations clearly state the importance of including dairy products including milk, cheese and yogurt in the diet (1FSA 2011, 1USDA 2011). These recently updated versions of existing government guidelines do now include some alternatives to dairy products in acknowledgement of the fact that certain people have digestive issues concerning dairy, including lactose intolerance, a condition where the lactase enzyme that catabolizes lactose, the protein in milk, is absent. This can lead to abdominal bloating, discomfort and diarrhea (Allergy UK 2012). The Myplate model now includes lactose-free milks and calcium-fortified soymilk under its’ dairy recommendations (2USDA 2007). According to Walter Willet, Professor of Epidemiology and Nutrition at the Harvard School of Public Health, the continued presence of dairy in such significant proportions on the MyPlate model owes more to the influence of the Agriculture Industry and less to science itself. In response he has devised the Healthy Eating Plate which recommends no more than 1-2 servings of dairy per day (MyPlate recommends 3 cups per day) based on the lack of evidence that high dairy consumption leads to any immunity against osteoporosis (Harvard School of Public Health 2011).

    No conclusive evidence exists to prove that milk prevents osteoporosis. Counties such as Japan, whose population consumes very little dairy, have lower incidences of osteoporosis than in the US or the UK. This suggests that dietary influences other than milk consumption may have a role to play in bone health. Dairy products, especially hard cheeses and all other animal proteins, score highly on the Potential Renal Acid Load (PRAL) scale. Research into whether these foods with a higher acid-forming effect on the body may lead to greater loss in bone mass density (BMD) is inconclusive, however a potential protective role from n-3 PUFA intake was drawn. (Pedone et al. 2010).

    An evidence based review of the data concerning milk and its role in human health, published in 2014 concluded that there is no finite link between the consumption of cows milk and an increase in risk of cardiovascular disease. In some instances the mineral components including calcium, potassium and magnesium may exert positive protective benefits for some individuals due to the antihypertensive effect of these minerals (Pererira 2014). Pereira continues the debate addressing the issue of cancer, which, similarly, drew inconclusive findings. If some components of milk, namely calcium, folate and Vitamin D can play a protective role against some cancers, other components may prove to be more carcinogenic. Circulating IGF-1, insulin-like growth hormone is significantly increased by milk consumption and is found to promote increased risk for breast cancer and prostate cancers (Quin et al. 2009).

    In the past, accusations have been drawn that the powerful Dairy Industry has had too much influence over government guidelines and that the message about milk has only included the positive associations between milk and bone health. No by-line was ever added to these campaigns to suggest that calcium can also be obtained from dark leafy vegetables such as kale and broccoli (Heaney et al 1990), leading me to conclude that the benefit of including calcium in the diet was of lesser importance to the lawmakers than the benefit of including the Dairy Industry in the story.

    For those who can tolerate milk, distinctions should be drawn between conventionally produced milk and organic milk. In 2007 the FSA commissioned a report to examine those differences and concluded that the higher levels of A-linolenic acid (ALA) found in organic milk could make a “contribution to changing the n-3 PUFA intake of the United Kingdom population (2FSA 2007). According to research carried out by Micinski (2013), cows milk fat with n-3 PUFAs has properties to protect against atherosclerotic plaque formation and is more beneficial to our health than fats that are available from vegetable oils.

    The evidence is certainly not conclusive and moderation should perhaps be the best approach with regards to dairy in the diet until researchers can ascertain the true extent to which it benefits or detriments our health. This lack of certainty is at odds with the positive messages espoused by both the US and the UK government guidelines on healthy eating. Whilst the research is ongoing and widely available for review if one chooses to look, the advice from the government belies the debate and for that reason I could not safely say that the information is balanced.

    I would also like to draw your attention to a report, which was published in the British Medical Journal (2014). Senior professors and researchers from Sweden have studied whether high consumption of milk is associated with fracture and mortality risk. Two major cohort studies, incorporating over 100,000 participants were conducted over a period of 2o years. Milk was found to be linked to higher fracture risk and mortality in women and higher mortality in men. Although men did not show increased risk of fracture there were positive indicators of higher markers for oxidative stress and inflammation. A by-product of enzymatic lactose digestion is D-galactose. In lab mice, D-galactose is injected to bring about the acceleration of aging, shortened life span, chronic inflammation and a decreased immune response. Milk produces a higher intake of D-galactose in the body than from any other source by more than one hundred fold. Fermented dairy products such as yogurt and some cheeses do not contain the lactose enzyme and therefore no D-galactose. Indeed fermented dairy consumption is associated with lower fracture risk and mortality; it is also associated with decreased risk of cardiovascular diseases.
    Lactose and D-galactose in milk may therefore be the catalyst for greater health deterioration and a higher rate of mortality when consumed in large quantities with no evidence of improvement in fracture risk to justify the positive associations that are globally espoused at the present time.

    Michaëlsson, K., Wolk, A., Langenskiöld, S., Basu, S., Warensjö Lemming, E., Melhus, H. and Byberg, L. (2014) Milk Intake and risk of Mortality and Fractures in women and men: cohort studies. The British Medical Journal 2014(349) p.6015

    References

    Allergy UK (2012) Dairy Intolerance. [Online]. Available at: http://www.allergyuk.org/common-food-intolerances/dairy-intolerance [Accessed: 14 October 2014].

    1Food Standards Agency (2007) Guidelines for use and reproduction of the eatwell plate model [Online]. Available at: http://www.food.gov.uk/scotland/scotnut/eatwellplate/guidelines [Accessed: 14 October 2014].

    2Food Standards Agency (2007) Organic Milk Workshop [Online]. Available at: http://tna.europarchive.org/20120419000433/http://www.food.gov.uk/multimedia/pdfs/orgmilkwork.pdf Accessed 02 October 2014].

    Harvard School of Public Health (HSPH) (2011) Harvard researchers lauch Healthy Eating Plate [Online]. Available at: http://www.hsph.harvard.edu/news/press-releases/healthy-eating-plate/ [Accessed: 15 October 2014].

    Heaney, R.P. and Weaver, C.M. (1990) Calcium absorption form Kale. The American Journal of Clinical Nutrition. (51) p.656-7.

    Miciński, J., Zwierzchowski, G., Kowalski, I.M., Szarek, J., Pierożyński, B and Raistenskis, J. (2012) The effects of bovine milk fat on human health. Polish Annals of Medicine. 19(2) p. 170-175.

    Michaëlsson, K., Wolk, A., Langenskiöld, S., Basu, S., Warensjö Lemming, E., Melhus, H. and Byberg, L. (2014) Milk Intake and risk of Mortality and Fractures in women and men: cohort studies. The British Medical Journal 2014(349) p.6015

    Pedone, C., Napoli, N., Pozzilli, P., Bandinelli, S. Ferrucci, L. and Antonelli-Incalzi, R. (2010) Quality of diet and potential renal acid load as risk factors for reduced bone density in elderly women. Bone. 46(4) p. 1063-1067

    Quin, L.Q., He, K. and Xu, J-Y. (2009) Milk consumption and circulating insulin-like growth factor-I level: a systematic literature review. International Journal of Food Science and Nutrition, 60(7), p. 330–340.

    1United States Department of Agriculture (USDA) (2007) ChooseMyPlate: What is MyPlate? [Online]. Available at: http://www.choosemyplate.gov/about.html
    [Accessed: 15 October 2014].

    2United States Department of Agriculture (USDA) (2007) ChooseMyPlate: What foods are included in the dairy group? [Online]. Available at: http://www.choosemyplate.gov/food-groups/dairy.html [Accessed: 15 October 2014].

    Like

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s