As a lover of cheese, I was concerned at a recent analysis of 32 studies that showed a potential link between prostate cancer and dairy intake. Although I don’t own a prostate myself, three members of my household do – and they share my delight in a nice runny brie, a baked Camembert and a ploughman’s slab of Cornish cheddar.
Researchers writing in the American Journal of Clinical Nutrition found an association between high intakes of various dairy foods, especially cheese, and an increased risk of prostate cancer. For cheese, the relative risk increased by 10% for every 50 grams consumed per day, although there was no significant association between cheese intake and fatal prostate cancer.
For men with the highest milk intake, the relative risk of receiving a diagnosis of prostate cancer was 11% greater than for those who drank the least milk, with the risk increasing by 3% for every 200 grams consumed per day. Oddly, whole milk seemed to offer slight protection, while low-fat milk increased the relative risk by 6% for every 200 grams consumed per day. Again, no link was found between drinking milk and fatal prostate cancer.
No association was found for skimmed milk, ice cream or butter either, although the number of studies available was limited.
So what would I do if I were male?
Milk and dairy products are an important source of vitamins and minerals, including calcium, phosphate, thiamin, riboflavin and vitamin B12, while full-fat dairy products are also good sources of the fat-soluble vitamins A, D, E and K. Rather than cutting them out entirely, it may make sense to cut back. I would continue to enjoy my regular cheese fests but I might swap some (but not all) of my mugs of black tea with milk for green tea which has a protective effect against prostate cancer. I would experiment with soy milk, yogurt and vegan cheeses, as well as increasing my intake of Asian-style foods associated with a lower risk of prostate disease, as described below, and which probably offer some benefits against other hormone-related cancers such as those of the breast and ovaries, too.
The link between prostate cancer and diet
Prostate cancer is the second most common cancer in men worldwide. The highest rates are reported in the US and Sweden, while the lowest rates are in Japan, India and China. Yet, just as many Asian men appear to develop early prostate cancer as Western males; the difference is that these tumours are more likely to remain small, slow-growing and clinically insignificant in those who follow a traditional Asian diet.
When native Japanese or Chinese men migrate to the West and adopt a more Western-style diet, their risk of clinically significant prostate cancer quickly increases. Among Japanese men in the US, for example, the incidence of prostate cancer is four times higher than for men still living in Japan; for Chinese men living in America, the incidence is seven times higher than for men still living in China. This strongly suggests that dietary and lifestyle habits are involved. Researchers have identified many foods that appear to offer some protection against prostate diseases in general, including BPH, prostatitis and the progression of prostate cancer.
Soy beans protect against prostate cancer
A large analysis of data from eight studies found that men who ate the most soy foods were 30% less likely to develop prostate cancer than men who ate the least; other studies have identified tofu as one of the most protective soy products. A Scottish study involving over 900 men also showed that, even in the UK, men who ate the most soy foods were 48% less likely to receive a diagnosis of prostate cancer than those with the lowest intake. In this Scottish study, dietary lignans (from foods such as flaxseed, lentils, pumpkin seeds and sweet potato) were also protective – men with the highest blood levels were 60% less likely to receive a prostate cancer diagnosis than those with the lowest levels.
Tomatoes protect against prostate cancer
A large analysis of data from 17 studies shows that men with the highest intake of raw or cooked tomatoes were 15% to 19% less likely to develop prostate cancer than those with the lowest intakes.
The protective ingredient is most likely the red carotenoid pigment, lycopene, which protects the fruit from sunburn.
Lycopene is locked away inside tomato cells, especially in the skins, which contain up to five times more lycopene than the pulp (so don’t peel them). When tomatoes are cooked, they release five times more lycopene than is available for absorption if you ate the same tomatoes raw. Tomato ketchup, passatta and tomato purée are therefore among the richest dietary sources.
Yes, pizzas are potentially good for the prostate gland – as long as they’re not smothered in cheese, and especially if they’re laden with garlic, my favourite condiment. And as a bonus tomato extracts can help to thin the blood to protect against unwanted blood clots, too.
Garlic protects against prostate cancer
Garlic has numerous identified anti-cancer properties and, as a bonus, tastes rather good.
An analysis of nine studies showed that men with the highest total intake of allium vegetables (such as onions, leeks, scallions, chives) were 18% less likely to develop prostate cancer than those with the lowest intake, and combing through the data revealed that garlic provides the greatest protective effect with a 33% reduced risk for those consuming the most.
Pak choy reduces prostate cancer risk
If you love broccoli, cabbage, kale and pak choy, you’re also in luck. These cruciferous vegetables contain sulphurous compounds known as glucosinolates which, when the plants are crushed, chopped or chewed, release hot or bitter-tasting chemicals.
These substances discourage animals from eating them, but we tend to find them tasty and gain the benefit of their anticancer actions.
Average Western intake of glucosinolates varies from around 2.8 mg per day in Finland to 14.5 mg in Germany, 22.5 mg per day in the US and 50 mg in the UK (a nation of cabbage and turnip lovers). In comparison, men following a traditional Asian diet may consume 300 mg or more of glucosinolates per day.
Analysis of data from 13 studies showed a 10% decreased risk of prostate cancer in men with the highest intake of cruciferous vegetables; in case-controlled studies which compared similar men with and without cancer, those eating the most enjoyed a 21% reduced risk.
Drink green tea
Another good strategy is to drink green tea, which provides a host of protective antioxidants with powerful cancer-fighting actions.
Pooled data from 21 studies confirmed a dose-response association with the greatest protection seen in China (60% reduced risk) and India (52% reduced risk). Protection was mostly against low-grade prostate cancer, however.
Click here for my tips on nutritional approaches to reduce benign prostate enlargement (BPH).
Image credits: cx_ed/freeimages, K.B.R./flickr; philippe_put/flickr