Prostate cancer: a not-so-hard nut to crack
The prostate is a male reproductive gland about the size of a walnut which sits behind the bladder. It produces some of the fluid that helps sperm on its mission to fertilise a woman’s egg. For such a little thing, it certainly causes a lot of problems. Cancer of the prostate is the second most common cause of cancer death in UK men, after lung cancer (Cancer Research UK, 2012). About one in nine men will develop it at some point in their lives, with over a half of them being 70 or over. There are many different factors that influence the development of this type of cancer and experts think that just five to 15 per cent are linked to inherited genes (Macmillan Cancer Support, 2013). It means that 85 per cent plus of cancers of the prostate are caused by environmental and/or lifestyle factors. Research suggests that obesity, animal-based diets and a lack of exercise may be linked to cancer in the prostate. Again, a diet high in animal fats may increase your risk. Foods with high levels include red meat (beef, lamb and pork), eggs and dairy produce, including butter, whole milk, cheese and cream. As with breast cancer, the highest rates of cancer of the prostate occur in the developed world, the lowest rates being in Africa and Asia. A global look at the problem confirms that there are clear links with diet; UK vegetarians are half as likely to get this type of cancer as meat eaters (NHS, 2006). But dairy products are also strongly linked to prostate cancers and this was first discovered in the 1980s (Snowdon, 1988). Since then, other studies have identified the components of milk which are probably responsible and these include oestrogen, the growth hormone IGF-1, calcium from milk and dairy protein (Butler, 2014). For example, an important European Prospective Investigation into Cancer and Nutrition (EPIC) study found that a 35g per day increase in consumption of dairy was associated with increasing the risk of cancer of the prostate by one third. They also found that calcium from dairy products was positively associated with risk, but not calcium from other foods (Allen et al, 2008). Men with higher than normal IGF-1 levels have been shown to increase their risk of advanced stage prostate cancer by five times (Chan, 2002). Our bodies increase their production of IGF-1 when we eat meat and dairy. In a more recent study looking at adult milk drinkers, increased dairy consumption is shown to be a major dietary risk factor for the development of this specific type of cancer. It showed how bioactive molecules in cows’ milk initiate a signalling pathway and that this, along with constant exposure to cows’ milk oestrogens, may explain the link between high dairy consumption and increased risk of cancer of the prostate in Westernised societies (Melnik et al, 2012). Increasing your intake of tomatoes (including tomato paste, tinned and cooked tomatoes), beans, lentils, peas, raisins, dates and other dried fruit (Mills, 1989) and flaxseed significantly reduces the risk of cancers of the prostate. Vegetables linked with stopping or slowing this particular cancer's cell growth in a petri dish include (most powerful first) garlic, Brussels sprouts, green onions, leek, broccoli, cauliflower, kale, brown onions, cabbage, beetroot, jalapeno, red cabbage, celery, orange bell peppers, spinach, cucumber, radicchio, asparagus, fennel bulb, radish, aubergine, potatoes, tomatoes and bok choy (Boivin, 2009). A review of 25 studies on the effect of diet on cancers of the prostate in real life cases (rather than in a petri dish) found that a vegan diet may slow cancer growth in the prostate and improve survival (Berkow et al, 2007).