Can Diet Prevent cancer?
This is a huge topic, and it would need a book to answer the question properly. In fact a great place to start is with Dr Servan-Schreiber's 'Anti-Cancer, A New Way of Life'. This blog has been adapted from a series of talks I gave at Clifton Village Library and is meant as an introduction to the topic. It provides simple but important information about why cancerous cells are different to non cancerous cells, looks at some potentially cancer causing foods and ways you can change your diet and lifestyle, making your body a less hospitable environment for cancer to thrive.
What is different about cancer cells ?
Cancer cells are:
Insensitive to anti-growth signals
Able to self-renew
Able to evade apoptosis (programmed cell death)
Able to create angiogenesis (own blood supply)
Able to divide, grow and invade unregulated.
Genes within these cells code for cancer type behaviour, like growth & invasion. These genes become active through mutations. Cancer develops when for various reason the immune system is unable to identify and destroy the cancer cells.
What causes the cell mutations that may lead to cancer?
Many experts now believe that few cancers are caused by genetics whereas most are rooted and significantly influenced by environment and lifestyle such as:
Long-term inflammation (caused by, for example: stress, alcohol abuse, poor diet, lack of exercise). Inflammation encourages cell growth, damages DNA and is closely linked to tumour growth
Cigarettes we know all about – I’m not going to go into that here
Alcohol – the equivalent of a pint or larger a day increases colon cancer risk by 25%. Why? It destroys folate (which should restrict tumour growth); damages the stomach lining; increases inflammation
Obesity is strongly associated with many cancers (20% of all deaths from cancer in women in USA) due to an increase in inflammation, energy and hormone imbalance
Other risks: pollution; industrial chemicals; medication; infectious agents; physical inactivity; hormone imbalance e.g. excessive oestrogen or insulin
Can good nutrition prevent cancer?
As many as 35% of cancer cases are linked to diet. 70% of colorectal cancer cases are linked to diet. Equally there are 25,000 different phytochemicals identified in foods that have potential cancer fighting actions. Therefore yes, a good diet can help to prevent cancer. For example:
Carotenoids: (including lycopene found in tomatoes) help prevent damage to cells and DNA caused by oxidative stress and limit cell growth. 10 mgs of lycopene a day has been shown to be effective. 2 tbs of tomato paste = 13 mgs of lycopene. 1 glass of tomato juice = 25 mgs of lycopene
Resveratrol: limits growth by triggering programmed cell death and inhibiting inflammatory cascade (found in red wine?! See more examples below)
Indol – 3 – Carbinol: encourages liver detoxification of carcinogens. Particularly effective with oestrogen (found in broccoli – see more below)
Curcumin: found in Turmeric, the anti-cancer effects of this nutrient have been indicated by 3000 published studies. One study showed a decrease in number of polyps by 60% after consumption of curcumin (all colon cancer starts as a polyp).
So, what food should I be eating and what should I avoid?
Limit/avoid:
Salt (damages lining of stomach, increases risk of high blood pressure)
Artificial sweeteners (aspartame found in brain tumours)
Saturated fats
Refined sugars and high glycemic index foods like white rice, white bread, white potato (high sugar increases risk for pancreatic cancer, high carb/insulin promotes cell growth)
Red meat (inflammatory & heating meat creates carcinogens particularly BBQ – marinade your meat to protect it)
Cured meats (e.g. bacon, ham – the nitrates/nitrites are carcinogenic)
Excessive dairy (encourages growth)
However, eating a lot of cancer fighting food is more important than never eating carcinogenic food. The American Cancer Research Institute (A.C.R.I) says: 2/3rds of your plate should be vegetables, whole grains and pulses.
What to eat: Whole grains contain chemo protective antioxidants Vita E, phytic acid and lignans (more than many fruit and vegetables) and high levels of fibre, which reduce the risk of many cancers. Fibre keeps digestion moving, limiting our contact with carcinogens. Fermented, insoluble fibre is a tumour suppressor (fibre needs per day = 30-35g. ½ cup cooked squash = 5 g; 1 cup raspberries = 8 g, ½ cup beans =7g; all bran cereal portion = 13g). And eat a lot of the fruit and vegetables below:
Carcinogenic blocking agents:
Ellagic Acid: Blackberries, cranberries, pecans, pomegranates, raspberries, strawberries, walnuts, and grapes
Indol 3 Carbinol, Sulphoraphane: Broccoli, brussel sprouts, cabbage, cauliflower, collard greens, kale, mustard greens, radish, turnip, broccoli sprouts
Flavanoids: Apples, almonds, celery, blueberries, romaine lettuce, tomatoes
Organosulphar compounds: Garlic, onions, leeks and chives
Omega 3: SMASH oily fish – salmon, mackerel, anchovy, sardines, herring
Cancer Suppressing Agents
Once a cell has undergone mutation, certain nutrients encourage cell apoptosis (cell death) and DNA repair. Many of the above agents are effective, plus:
Beta Carotene: Carrots, mangos, pumpkins
Lycopene: Tomatoes (cooked, with oil) watermelons
Curcumin: Turmeric (cooked, with black pepper)
EGCG: Green tea (3-5 cups)
Genistein: Soya products, red beans
Resveratrol: Red grapes, peanuts, grapes, red wine, blueberries, cranberries, cocoa
Gingerol: Ginger
Capsaicin: Sweet bell peppers and spicy chili peppers
Folate: Green leafy veg, asparagus, avocado
Retinoids: Beef, calf, and chicken liver, eggs, fish liver oils, dairy products
Polyphenols: Herbs and spices: Cloves, star anise, dried oregano, cocoa powder, flaxseed
AICR recommends: 7-10 portions a day. Approx. 1 uncooked cup food = 1 portion.
Numerous studies have shown that cancer rates are significantly lower in vegetarians. However, vegetarians that don’t eat many vegetables and eat a lot of junk food have similar levels of cancer!
‘’High fruit and vegetable intake may reduce cancer rates and mortality by 1/3” US National Research Council
That’s roughly equivalent to the reduction in mortality from infectious diseases brought about by improved hygiene and better healthcare during the 19th century!
Calorie restriction has also been shown to be cancer protective - hence the increase in interest in fasting for short periods or limiting how much you eat on one or two days of the week.
Other things to consider:
Medicinal mushrooms, Melatonin, Pau d’arco, Omega 3 fish oils, CBD oil (non psycho-active element of cannabis), Vitamin C, Pancreatic Enzymes and Essiac Tea may help to boost the immune system, encourage the death of damaged cells or protect against chemo therapy damage. Probiotics can improve digestion so that helpful nutrients are more easily absorbed. They may also limit carcinogens being reabsorbed in the bowel and it has been suggested that healthy gut bacteria may protect against colon cancer.
There are many supplements that can be used, but diet should be the corner stone of your self care.
Stress and the immune system
Ongoing stress leads to poor immunity because it increases the stress hormone cortisol. Cortisol impairs DNA repair and can interfere with the death of damaged cells. In this way, stress indirectly contributes to the development and progression of some types of cancer.
So, to summarise in plain English.....
Eat a bit less if you are used to over eating
Eat more fruit and vegetable than you ever thought possible - of every colour of the rainbow - at every meal
Eat low GI food – i.e. slow release carbs like oats, brown rice, sweet potatoes rather than white bread, white rice or mars bars!!
Relax - seriously - its very very important
Exercise as much as you comfortably can - build it up slowly.
And finally it has been shown that those with strong social connections (not just family - friends are equally important) and a sense of purpose, are the most likely to live long, healthy lives.
Note: Beta Carotene supplements should not be taken by lung cancer patients. It is always best to check your supplement regime with a doctor, especially if you are taking medication or undergoing mainstream cancer treatments.
Sources
American Dietic Association (2001). Colorectal cancer, J American Diet Association (Jan)
Anand P et al (2008) Cancer is a preventable disease that requires major lifestyle changes. Pharmaceutical Research Sep;25(9):2097-116
Aschuler and Gazella (2010). The definitive Guide to Cancer. Innovision Media.
Larson et al (2006) Consumption of sugar and sugar-sweetened foods and the risk of pancreatic cancer in a prospective study 1,2,3 American Journal of Clinical Nutrition Vol 84 No 5 1171-1176
National Cancer Institute: PDQ® Cancer Information Summaries: Integrative, Alternative, and Complementary Therapies
Pizzorno and Murray (2013) Textbook of Natural Medicine: Fourth Edition. pg 440-460
Reddy (1992) Dietary Fat & Colon Cancer. Lipids vol 27 no 10 807-813
Servan-Schreiber (2011) Anti-Cancer, A New Way of Life. Revised Edition
Walters R ‘Options (1993), The alternative Cancer Therapy Book. Paragon Press
World Cancer Research Fund and American Institute for cancer Research (2007): Food, Nutrition, Physical Activity and the prevention of cancer, a global perspective.