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 health 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).
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.
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