Are Dairy-Free Diets A Risk To Bone Health?

I applaud the Duchess of Cornwall for highlighting the issue of osteoporosis, which can be a debilitating condition.

However, to cite dairy-free diets as harmful to bone health is just ignorant and not based on scientific data. A healthy diet and lifestyle is fundamental to preventing osteoporosis. Important nutrients for bone health include calcium, potassium, magnesium, vitamin K and vitamin D, which can all be obtained on a healthy plant-based/vegan diet.

The dairy industry has very successfully propagated the myth that dairy consumption is essential for optimal calcium intake, yet lactose intolerance (the inability to break down the sugar in milk) is common, affecting 50–95 percent of people in many non-Caucasian populations (Bayless, Brown, & Paige, 2017).

Consumption of dairy has not been shown to improve bone health or prevent osteoporosis and bone fractures (Bischoff-Ferrari et al., 2011; Bolland et al., 2015). In fact some studies find that milk consumption is associated with a higher fracture rate (Michaëlsson et al., 2014). Consumption of milk in adolescence does not appear to prevent fractures in later life (Feskanich, Bischoff-Ferrari, Frazier, & Willett, 2014).

Detrimental health effects

The consumption of dairy has actually been more consistently linked with detrimental effects on health. Dairy, including milk and cheese, is one of the top sources of saturated fat in the typical Western diet. Diets high in saturated fat increase the risk of heart disease, stroke and dementia (Ludwig, Willett, Volek, & Neuhouser, 2018).

The consumption of dairy products has been associated with an increased risk of prostate cancer in men (Aune et al., 2015) and an increased risk of lung, breast and ovarian cancer (Ji, Sundquist, & Sundquist, 2015). There are a number of reasons why dairy may promote cancer, including the main milk protein, casein, which in the laboratory has been shown to promote cancer growth (Youngman & Campbell, 1991).

Dairy consumption elevates oestrogen levels in the blood, which promotes female cancers (Michels, Binder, Courant, Franke, & Osterhues, 2019). Dairy, along with other sources of animal protein, elevates blood levels of the hormone IGF-1, which is a risk factor for cancer (Ma et al., 2001; Qin, He, & Xu, 2009). Vegans have a lower levels of IGF-1 when compared to omnivores (Allen, Appleby, Davey, & Key, 2002) and an overall lower rate of cancer (Dinu, Abbate, Gensini, Casini, & Sofi, 2017). Milk consumption has also been implicated in the development of acne in adolescence (Juhl et al., 2018).

Calcium intake

The optimal daily intake of calcium is also a matter of debate. 500mg per day is probably adequate for bone health with 700mg per day for adults recommended in the UK (Willett et al., 2019). A healthy plant-based diet can provide adequate amounts of calcium as summarised here by the vegan society. In fact, the recently published Eat-Lancet Commission on Food, Planet Health accepts that dairy is not required in the diet (Willett et al., 2019) and the 2019 Health Canada dietary guidelines to not include dairy as an essential component of the diet (Health Canada, 2019).

For optimal bone health, everyone should make sure they are getting enough vitamin D, which in the winter months when sun exposure is limited, may be best obtained through supplements as recommended by Public Health England. Vitamin K is also essential for bone health and can be obtained from leafy green vegetables. Take care with protein consumption, as contrary to popular belief, more is not always better and high protein diets, especially when protein is from animal sources, have been associated with worse bone health and higher fracture rates (Feskanich, Willett, Stampfer, & Colditz, 1996; Sellmeyer, Stone, Sebastian, & Cummings, 2001).

Other lifestyle-related factors important for bone health include regular, weight-bearing physical activity, avoiding tobacco smoking and minimising alcohol consumption (Zhu & Prince, 2015).

In conclusion, medical evidence does not support the need for dairy in the diet and its continued promotion by those in authority should be openly challenged and underlying motives questioned.

References

Allen, N. E., Appleby, P. N., Davey, G. K., & Key, T. J. (2002). Hormones and diet: low insulin-like growth factor-I but normal bioavailable androgens in vegan men. British Journal of Cancer. https://doi.org/10.1054/bjoc.2000.1152

Aune, D., Navarro Rosenblatt, D. A., Chan, D. S. M., Vieira, A. R., Vieira, R., Greenwood, D. C., … Norat, T. (2015). Dairy products, calcium, and prostate cancer risk: A systematic review and meta-analysis of cohort studies. American Journal of Clinical Nutrition. https://doi.org/10.3945/ajcn.113.067157

Bayless, T. M., Brown, E., & Paige, D. M. (2017). Lactase Non-persistence and Lactose Intolerance. Current Gastroenterology Reports. https://doi.org/10.1007/s11894-017-0558-9

Bischoff-Ferrari, H. A., Dawson-Hughes, B., Baron, J. A., Kanis, J. A., Orav, E. J., Staehelin, H. B., … Willett, W. C. (2011). Milk intake and risk of hip fracture in men and women: A meta-analysis of prospective cohort studies. Journal of Bone and Mineral Research. https://doi.org/10.1002/jbmr.279

Bolland, M. J., Leung, W., Tai, V., Bastin, S., Gamble, G. D., Grey, A., & Reid, I. R. (2015). Calcium intake and risk of fracture: Systematic review. BMJ (Online). https://doi.org/10.1136/bmj.h4580

Dinu, M., Abbate, R., Gensini, G. F., Casini, A., & Sofi, F. (2017). Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Critical Reviews in Food Science and Nutrition. https://doi.org/10.1080/10408398.2016.1138447

Feskanich, D., Bischoff-Ferrari, H. A., Frazier, A. L., & Willett, W. C. (2014). Milk consumption during teenage years and risk of hip fractures in older adults. JAMA Pediatrics. https://doi.org/10.1001/jamapediatrics.2013.3821

Feskanich, D., Willett, W. C., Stampfer, M. J., & Colditz, G. A. (1996). Protein consumption and bone fractures in women. American Journal of Epidemiology. https://doi.org/10.1093/oxfordjournals.aje.a008767

Health Canada. (2019). Canada’s Dietary Guidelines. Retrieved from https://food-guide.canada.ca/static/assets/pdf/CDG-EN-2018.pdf

Ji, J., Sundquist, J., & Sundquist, K. (2015). Lactose intolerance and risk of lung, breast and ovarian cancers: Aetiological clues from a population-based study in Sweden. British Journal of Cancer. https://doi.org/10.1038/bjc.2014.544

Juhl, C. R., Bergholdt, H. K. M., Miller, I. M., Jemec, G. B. E., Kanters, J. K., & Ellervik, C. (2018). Dairy intake and acne vulgaris: A systematic review and meta-analysis of 78,529 children, adolescents, and young adults. Nutrients. https://doi.org/10.3390/nu10081049

Ludwig, D. S., Willett, W. C., Volek, J. S., & Neuhouser, M. L. (2018). Dietary fat: From foe to friend? Science. https://doi.org/10.1126/science.aau2096

Ma, J., Giovannucci, E., Pollak, M., Chan, J. M., Gaziano, J. M., Willett, W., & Stampfer, M. J. (2001). Milk intake, circulating levels of insulin-like growth factor-I, and risk of colorectal cancer in men. Journal of the National Cancer Institute. https://doi.org/10.1093/jnci/93.17.1330

Michaëlsson, K., Wolk, A., Langenskiöld, S., Basu, S., Lemming, E. W., Melhus, H., & Byberg, L. (2014). Milk intake and risk of mortality and fractures in women and men: Cohort studies. BMJ (Online). https://doi.org/10.1136/bmj.g6015

Michels, K., Binder, N., Courant, F., Franke, A., & Osterhues, A. (2019). Urinary excretion of sex steroid hormone metabilutes are consumption of cow milk: a randomized corssover intervention trial. The American Journal of Clinical Nutrition, 109(2), 402–410.

Qin, L. Q., He, K., & Xu, J. Y. (2009). Milk consumption and circulating insulin-like growth factor-I level: A systematic literature review. International Journal of Food Sciences and Nutrition. https://doi.org/10.1080/09637480903150114

Sellmeyer, D. E., Stone, K. L., Sebastian, A., & Cummings, S. R. (2001). A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women. American Journal of Clinical Nutrition.

Willett, W., Rockström, J., Loken, B., Springmann, M., Lang, T., Vermeulen, S., … Murray, C. (2019). Food in the Anthropocene: the EAT–Lancet Commission on healthy diets from sustainable food systems. Lancet, 6736, 3–49. https://doi.org/10.1016/S0140-6736(18)31788-4

Youngman, L. D., & Campbell, T. C. (1991). High protein intake promotes the growth of hepatic preneoplastic foci in Fischer #344 rats: Evidence that early remodeled foci retain the potential for future growth. Journal of Nutrition. https://doi.org/10.1093/jn/121.9.1454

Zhu, K., & Prince, R. (2015). Lifestyle and osteoporosis. Current Osteoporosis Reports, 13(1), 52–59.