Diet and prostate cancer
Nicholette Shadanloo, a Nutritional Therapist and Molecular Biologist, provides information below about diet and prostate cancer prevention. Nicholette graduated from the University of St Andrews in Scotland and is currently practicing at the Cromwell Hospital.
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The importance of the role that nutrition plays in cancer prevention has become increasingly evident. Studies of population groups around the world indicate that diets rich in whole plant foods are linked with a lower risk of certain cancers. This may be partly evidenced by the fact that men living in Asian countries (China, Japan and the Philippines), are 10-15 times less likely to develop prostate cancer than men living in America, although genetic factors will also play a role.
Diets high in fruits and vegetables have been connected to a reduced risk or delay in the onset of prostate cancer. Fruits and vegetables, which are rich in antioxidants and phytochemicals, defend the body against free radical damage and combat the level of oxidative stress and inflammation, preserving normal cellular function.
Each meal presents a choice; uphold your nutritional balance by consuming nutrients, or create a pro-inflammatory environment by eating foods that increase oxidative stress and increase the risk of cancer. Each time one sits down to eat, often unknowingly, one is making this choice.
Anti-inflammatory, alkalising foods for a preventative diet
- Whole Plant Foods
- Fibre Rich Foods
- Essential Fatty Acids
- Saturated and trans fats
- Processed foods
- Animal products: red meat and dairy
- Alcohol (should also be limited as it is a carcinogen and promotes the generation of ROS as well reducing antioxidant levels in the body)
Reactive Oxygen Species (ROS) are reactive oxygen containing molecules, which can damage proteins, fats and DNA. Oxidative stress is amplified not only by the aging process but also by environmental stress. This process eventually leads to systemic inflammation, which may increase one’s risk of developing cancer.
Chronic inflammation has been linked to the incidence of prostate cancer. Prostatitis is an inflammatory condition of the prostate (due to bacterial or viral infections). Suffering from this condition leads to a higher exposure of free radicals, which damages the DNA, due to chronic inflammation. Therefore, consuming a diet that is rich in antioxidants could prevent the development of prostate cancer by combating the DNA damage. Addressing the inflammation is also key in preventing damage to the DNA and therefore a diet rich in anti-inflammatory foods and herbs such a broccoli, blueberries, turmeric, salmon and green tea may reduce the chances of developing prostate cancer.
The US National Cancer Institute has stated that consuming 5 servings of fruits and vegetables a day is now the bare minimum. Ideally, men should be consuming 9 servings of fruits and vegetables a day to give them the best chance of preventing cancer. This can be in the form of fresh pressed juices, smoothies, soups and stews. Evidence of this has been so compelling that the leading cancer related institutions have all recommended a dietary increase in the following:
- Cruciferous vegetables
- Green and yellow fruits and vegetables
- Citrus fruits
- Fruits and vegetables that have high levels of Vitamin A and C.
Flavonoids, which are abundant in fruits and vegetables, are a phytonutrient. They are powerful carcinogen detoxifiers and have the ability to inhibit many cancers. High levels can be found in onions, kale, Brussels sprouts, cabbage, broccoli, turnips, apples, pears, citrus fruit and grapes.
The 7-Day Adventists Study by the US National Institute of Health is one of the largest and longest studies comparing disease rates among vegetarians and non-vegetarians since 1958. This study concluded that vegetarians had a 54% lower risk of developing prostate cancer, as long as the diet was robust in protective whole and unprocessed foods.
Dairy and IGF-1
Animal protein, particularly dairy, raises Insulin like Growth Factor 1 (IGF-1). Men with raised IGF-1 have a 5 times higher risk of developing prostate cancer. Therefore, reducing dairy in your diet as well as reducing animal protein and opting for more plant-based protein such as lentils, beans and quinoa will lower your overall risk of developing the disease.
T. Colin Campbell PhD, states in The China Study that people who minimize animal products in their diet and increase whole plant foods or follow a vegan diet lower or reverse the development of chronic disease, including cancer. Campbell concluded that Chinese people consume less animal protein then the ‘Standard American Diet’ and as a result have lower cholesterol levels. Active vitamin D production is suppressed when animal protein is consumed, which is not beneficial from a disease prevention standpoint, as low levels of vitamin D have been linked with cancer and various autoimmune diseases.
The Journal of the National Cancer Institute concluded that consuming a diet that is high in tomatoes is associated with a lower prostate cancer risk. Lycopene is a carotenoid, which gives certain fruits its ‘red’ colour. It is also a powerful antioxidant. The principal source of lycopene is tomatoes, especially cooked and processed tomatoes (tomato sauce and paste), as this increases the bioavailability of the nutrient.
One of the most major studies published on the human health benefits of lycopene and prostate cancer prevention was the Health Professionals follow up study conducted in 1995. Over 47,000 men’s diets and eating habits were observed from 1986-1992. During the follow up period, 773 cases of prostate cancer were diagnosed (non-stage A1). Of all the fruits and vegetables that were consumed during the trial, tomatoes, tomato sauce and strawberries were most strongly associated with a reduced risk of prostate cancer.
A study was conducted on the Seventh-Day Adventists population. The diet of approximately 14,000 men was observed and after a 6-year follow up, 180 of those men were diagnosed with prostate cancer. The risk of prostate cancer was significantly lower in men who consumed 5 or more servings of tomato or tomato products per week compared to the men who consumed less than 1 serving per week.
Lycopene has the ability to inhibit insulin-like growth factor type 1 (IGF-1) induced cell proliferation. One study demonstrated that in the presence of a physiological concentration of lycopene, in combination with alpha-tocopherol (vitamin E), cell line proliferation was inhibited. Another study linked a higher dietary intake of tomatoes with lower levels of IGF-1.
Over 200 epidemiological studies have confirmed theories linking cancer and vitamin D deficiency. A study conducted over a 13-year period with 19,000 men from Finland concluded that those with low serum levels of vitamin D were at an increased risk of developing prostate cancer. It is therefore important to periodically have your levels checked and supplement if your levels fall below the ideal range. If you do require supplementation, it should be in the form of D3, which is a more potent form that delivers the best results for treating deficiency. Exposing bare skin to sunlight is the best approach for optimising vitamin D levels. Avoid mid-day sun, which can be very damaging and instead opt for sunbathing between 10-11am and after 2:30pm.
Phytoestrogens and green tea
A growing amount of interest and research has been focused on the actions and benefits of soy and green tea. This is due to the fact that prostate cancer is significantly lower in Asian countries where green tea and phytoestrogens are abundant in the diet as compared to the typical western diet of the US and UK. Phytoestrogens, such as isoflavones (soybeans), act as agonists and/or antagonists on estrogen and androgen receptors. A lower risk of prostate cancer has been associated with a diet rich in isoflavones. Green tea polyphenols (especially EGCG) are potent antioxidants and major inhibitors of carcinogen activation. Only 8% of the American population regularly consume green tea (180ml per day) as oppose to Asian countries that normally consume 360-480ml daily. Green tea and soy effectively target inflammation and have the potential to block inflammation during cancer progression. Chronic inflammation can play a role not just as a generator but also a promoter of prostate cancer and that is why it is a significant risk factor. Therefore, it is evident as to why diets rich in phytoestrogens and green tea have a major effect on the incidence of prostate cancer.
Excess body fat/obesity
Obesity/excess body fat increases the risk of cancer. Excess body fat promotes oxidative DNA damage and facilitates alterations in carcinogen metabolizing genes. It also impacts the immune system negatively, changes hormone metabolism and increase inflammation in the body. Therefore it is crucial to maintain a healthy weight and avoid consuming excess calories. If you are overweight or obese it is strongly suggested to see a nutritional therapist in order to safely and effective lose weight while nourishing your body to not only lower your risk of cancer but also prevent Type II diabetes and heart disease.
Organic produce contains higher levels of vitamins, minerals and antioxidants. Flavonoids are powerful inhibitors of cancer. However, chemical pesticides and fertilizers may infiltrate the food chain via fruits and vegetables and may have toxic carcinogenic effects on the body and may increase your risk of developing cancer.
Cooking food at high temperatures, especially directly in flame, produces chemicals that are carcinogenic and potentially mutagenic. Charcoal cooking and smoking or curing of meats produces harmful components such pyrolysates, which promote cancer cell development. Therefore, frying and grilling at high temperatures, especially barbequing, should be avoided as much as possible. Instead opt for lightly steaming and baking foods at lower temperatures (for longer periods).
Not only is the technique and temperature at which you cook foods important in terms of decreasing the levels of carcinogens you are exposed to, the oils you use to cook with are equally important. Avoid cooking at higher temperatures with vegetable oils or anything that is liquid at room temperature. Instead opt for coconut oil, which is stable at very high temperatures and is a medium chain fatty acid, making it one of the best oils to cook with.