Diet in 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 goal of diet in prostate cancer is to produce an internal environment that could potentially lower prostate specific antigen (PSA) levels. PSA progression is a surrogate for prostate cancer progression. Foods that are rich in antioxidants and have anti-inflammatory properties should be consumed in order to combat free radical damage, reduce tumor-promoting factors and inhibit metastasis and tumor progression. Dairy, red meat and sugar, which includes all pastries, sweets, processed, refined foods and alcohol, should be limited as much as possible in order to achieve these goals. Patients suffering from prostate cancer should consume a diet that is anti-inflammatory and alkalizing. Preventing spikes in insulin and maintaining blood sugar balance is essential as well as preventing raised IGF-1 levels.
Oxidative stress is inherent in prostate cancer cells and is the main reason for uncontrolled cell cycling and metastasis. That is why consuming a diet that is rich in antioxidants is crucial. Each meal should be an opportunity to incorporate as many nutrients and antioxidants into your body as possible. It is recommended that patients with prostate cancer consume at least10 portions of fruits and vegetables a day. This can be in the form of freshly pressed green juices and smoothies, soups and stews as well as raw and steamed vegetables.
The cellular membrane is composed of a phospholipid bilayer (2 layers of lipid molecules). The integrity of the membrane is crucial for maintaining normal cellular function. When free radicals damage the fatty acids in the membrane, it eventually causes damage to the DNA, which is a significant contributing factor in cancer. Incorporating beneficial essential fatty acids into the diet helps maintain the integrity and health of the cellular membrane, thus promoting normal cellular function as well as oxygen transport to the cell. Therefore, Omega 3 and 6 essential fatty acids play a major role in protecting us in cancer.
One of the best ways to repair and maintain the integrity of the cell membrane is to consume plant based oils such as flaxseed oil, which is rich in omega 3 fatty acids, especially when mixed with a sulfur rich compound such as cottage cheese, garlic and onions.
Vegetables fats such as olive oil, flaxseed oil, nuts, seeds and avocados could potentially allow patients with prostate cancer to live longer in conjugation with lowering animal fats. In one major study looking at the impact of dietary fats and prostate cancer, 4,577 men that were diagnosed with prostate cancer (which had not spread beyond the prostate) were observed over an 8-year period. The men in this study replaced 10% of their daily calories from carbohydrates to vegetable fat. The study concluded that these men were 29% less likely to pass away from prostate cancer because of this dietary change.
Saturated and trans fat should be avoided as much as possible. The main sources of saturated fat that should be avoided from the diet are red meat and dairy which are also inflammatory. Trans fats (found in fast food, packaged foods, spreads such as margarine, cookies, candy and crisps) raises ‘bad’ cholesterol (LDL) and reduces ‘good’ cholesterol (HDL). Trans fat is also inflammatory. Saturated and trans fat should be replaced by high quality beneficial fats such monosaturated and polysaturated fats.
A vegan diet that is abundant in whole foods, low in harmful fats and very limited in processed foods effectively lowers inflammation in the body. Studies have been conducted highlighting that after just 4 weeks of following a vegan diet full of fruits and vegetables, inflammation was lowered 3 times more effectively then a diet based on the traditional food pyramid.
A study was conducted observing the relationship between a vegan diet and prostate cancer survival. In a group of men, prostate specific antigen (PSA) levels decreased by 4% after 1 year on a low-fat vegan diet complimented with aerobic exercise and stress management (experimental group). The men in the control group witnessed a rise in PSA levels by 6%. No one in the experimental group needed treatment as oppose to the control group where 6 men required treatment because their prostate cancer was progressing. It should be noted that it is unusual for PSA levels to decrease without treatment. The study concluded that significant nutrition and lifestyle changes may potentially modify gene expression responsible for prostate cancer growth.
Green Tea and Phytoestrogens
Green tea promotes DNA repair and encourages apoptosis (programmed cell death) of damaged cells. It has anti-angiogenesis properties, which may prevent tumours developing their own blood supply. EGCG, a potent polyphenol found in green tea, has anti-carcinogenic properties and induces cell cycle arrest as well as reducing tumour promotion.
Isoflavones, found abundantly in soybeans, are a phytoestrogen that induces cell cycle arrest in prostate cancer cells. One study found that both PSA levels and the free/total PSA ratio in prostate cancer patients were decreased upon daily consumption of soy grits (soybeans which have been toasted).
The inflammatory response can potentially be blocked during cancer progression by green tea and soybeans. The Nuclear Kappa B pathway (NF- kappaB) may be an important element between prostate cancer, cell proliferation and long-term inflammation. Green tea works by targeting the NF- kappaB pathway. Targeting this pathway may restore normal cellular function by decreasing inflammation, encouraging apoptosis and decreasing cell-proliferation that is uncontrolled.
A study was conducted by Robert Thomas, an oncologist at Bedford Hospital (one of Cambridge University’s hospitals), looking at the therapeutic effects of green tea and pomegranate on prostate cancer. 203 men with prostate cancer were split into two groups and observed for 6 months. One group received a ‘placebo’ pill for half a year while the other group took a pill containing the essence of green tea, pomegranate, turmeric and broccoli. Researchers observed that PSA levels were 63% lower among the men in the therapeutic group taking the nutrient rich capsules compared to the men in the placebo group.
Pomegranates are rich in ellagitannins, which have powerful anti-inflammatory and antioxidant properties. Pomegranates also have the ability to suppress the activation of the NF- kappaB pathway. Therefore, this potent fruit is capable of decreasing cell proliferation and inducing apoptosis. One study found that pomegranate phytochemicals inhibited the in vitro proliferation of 3 prostate cancer cell lines, LNCaP, PC3 and DU145.
A study observed the PSA levels of 104 men after initial therapy for prostate cancer. The men were given 1 and 3 gram doses of pomegranate extract. Researchers concluded that PSA doubling times were increased by more than 6 months in both the 1g and 3 g treatment groups showing the therapeutic significance of pomegranates in prostate cancer.
Another study, conducted at the Jonsson Cancer Centre at UCLA, observed patients with recurrent prostate cancer. Patients who consumed 8 ounces of pomegranate juice daily after surgery or radiation treatment had PSA levels that doubled after 54 months as compared with the men who did not drink pomegranate juice, who’s PSA levels doubled in only 15 months.
Lycopene is a carotenoid, which gives certain fruit 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 important 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 and tomato sauce were strongly associated with a reduced risk of prostate cancer.
Consuming 10 portions of tomatoes products per week, as opposed to only consuming 1.5 portions, proved to be very protective in the men suffering with advanced prostate cancer (stage C or D).
One study demonstrated that in the presence of a physiological concentration of lycopene, in combination with alpha-tocopherol (vitamin E), cell line proliferation of prostate cancer cells was inhibited.
Exercising not only enhances immunity, it reduces pain, increases energy and vitality, improves digestion and aids sleep. It also improves circulation of the lymph and blood. Exercise has been shown to increase the survival after cancer diagnosis. 30 minutes of daily exercise during radiation was also shown to improve physical condition and result in less fatigue for the patient.
The University of Nebraska conducted a study, giving patients a 12-week exercise plan following chemotherapy. T cells normally become less effective at fighting disease after chemotherapy. After the 12-week exercise program, ‘old’ T cells were removed and new active T cells were produced. It was concluded that exercise prevented recurrence and secondary cancers by improving the immune system.