Diet and lifestyle has a greater influence on cancer than previously thought – This is what the evidence tells us we can do to half our risks.
About 400,000 people in the UK are diagnosed with cancer each year and just under half die of it. Previously, it was believed that about 30% of cancer deaths could have been prevented with a healthy lifestyle but new data from a comprehensive USA study published last week reports this nearer to 45%. I believe this figure could be even higher if other, more recently discovered, modifiable factors were considered in the analysis such as gut health, sleep deprivation and processed sugar intake.
Clearly, nobody should be blamed for contracting cancer. Thousands of men and women are devastated by this dreadful disease, who led perfectly healthy lives. Research however, empower us with the knowledge that we can significantly reduce our odds, albeit not completely. Many of these risk factors are obvious but others not so clear, This is what the evidence tells us are the most important factors:
Smoking is the main cause of lung cancer and strongly contributes to cancers arising in the bladder, kidney, skin, mouth and throat, oesophagus, stomach and pancreas. Smoking even causes a more aggressive type of prostate cancer.
Being overweight or obese increases the risk of cancers of the breast, bowel, prostate and uterus. The combination of abdominal obesity raised sugar, fats, blood pressure and inflammation, a condition called metabolic syndrome, is particularly harmful.
Regular exercise for about 2.5 – 3 hours a week, and avoiding long periods of sitting, have been linked to about a 30% lower cancer risk. Any exercise which increases heart and breathing rates is good but it’s important to find an activity which is enjoyable, hence sustainable including running, brisk walking and even cycling.
Get vaccinated for HPV. This is recommended for all children (boys and girls) between 11-13. It offers a high protection against cervical cancer as well as those arising in the anus, mouth, vagina and penis. This new data shows how successful this vaccination is.
Ensure adequate vitamin D levels as deficiency is linked to an increased risk of cancer, dementia, covid, depression and heart disease. Sun bathing, without burning, is the best way to increase vitamin D levels. Otherwise, vitamin D supplementation, especially if combined with a probiotic that enhances its effect, is a sensible alternative which we should all consider in the darker months and, if you can afford it, a winter holiday in the sun.
Avoid excess sun. Too much sun, can cause permanent skin damage and cancer. In particular, sun burning when young substantially increases the risk of melanoma which killed 2500 people last year and the death rate is increasing rapidly. Tips to stay safe in the sun include, covering up vulnerable areas like the face, neck and hands especially in more intense times of the day, applying sun block, using a good quality, olive oil based, after sun and eating skin protective foods.
Try to get a good night’s sleep: Chronic insomnia can lead to fatigue, demotivation to exercise and undertake healthy living programmes. In the longer term, it alters the circadian rhythm which causes abnormal cellular growth and altered DNA repair, which are the first steps to cancer formation. The International Agency for Cancer now classes sleep-disruption as a carcinogen. There are lots of dietary and lifestyle tips to improve sleep patterns
Having more sex or, more specifically, 20 or more orgasms a month for men, has been shown to reduce the risk of prostate cancer by over 30% compared to men who report having 4–7 ejaculations per month.
Be careful with alcohol: A few glasses of red wine a week has been linked to better gut health and a lower risk of prostate cancer, probably due to its high concentration of a phytochemical called resveratrol. It must be noted, however, that consuming more than two drinks a day increases the risk of bowel cancer, and any amount of alcohol increases the risk of breast cancer.
Eating more fruit, cruciferous vegetables, and spices increases the intake of healthy phytochemicals, which protect us from dementia and cancer by reducing excess inflammation and improving gut flora. There is some evidence that boosting the diet with phytochemical rich supplements may also have a role. In 2013, a blend of pomegranate, broccoli, green tea, and turmeric was found to slow the progression of prostate cancer. In 2024, the world’s largest nutritional intervention study for prostate cancer builds on this data by boosting phytochemical levels using targeted extracts and adding other foods such as cranberry and ginger, which further enhance its effectiveness and improves the absorption of all the phytochemicals.
Reducing meat and particularly processed meat intake such as grilled sausages, bacon, sliced ham and tinned meats will reduce the risk of cancer by 20% compared to low or no meat eaters. Processed meats contain toxins which increase inflammation and directly damage our precious DNA causing premature aging, cancer and other chronic diseases.
Avoid Ultra Processed Foods (UPF) are high in salt, sugar, nitrates, trans fats, colours, flavourings, and industrial contaminants, whilst low in fibre, minerals, vitamins and phytochemicals. They can cause oxidative stress, inflammation, obesity and reduced immunity. People who eat a lot of these foods such as cakes, biscuits, pastries, veggie and meat burgers also tend to eat less healthy foods. They are more prone to infections and cancer but also other condition which indirectly increase the cancer risk such as obesity, diabetes and poor gut health.
Carcinogens: We are surrounded by potentially toxic chemicals which can increase the risk of cancer by promoting inflammation, blocking cellular repair and triggering oxidative stress which damages our DNA. These include smoked food, aromatic amines in chargrilled meats, and acrylamides in superheated sugary snacks and cereals. Some environmental chemicals such as plastics, household cleaning agents and air pollution can promote cancers of the breast, testes, ovary and uterus via abnormal hormonal stimulation. It’s hard to eliminate all carcinogens but a good idea to limit exposure to as many as possible.
Poor gut health has been linked with a higher risk of many cancers, fatigue, low mood and demotivation to lead a healthy anti-cancer lifestyle. Factors which affect gut health include lack of exercise, processed sugar, smoking, obesity and stress. Bacteria rich foods such as kefir and kimchi help and probiotic capsules may have a role in boosting gut health especially in people with existing problems. As mentioned above, a combination of lactobacillus and vitamin D was chosen by the scientific committee for latest national intervention studies for covid, the covid vaccine, prostate cancer, exercise performance and other studies.
Ditch the processed sugar, especially in drinks, as this increases the risks of many diseases including arthritis which impedes exercise, obesity and cancer. Sugar feeds the unhealthy, pro-inflammatory bacteria in the gut, overloads insulin pathways and contributes to diabetes and weight gain. Adding sugar to tea or coffee also negates their otherwise protective benefits.
Eat more nuts helps reduces the risk of bowel and prostate cancer but more importantly it reduces the risk of death because nut eaters develop slower growing more curable cancers.
Keep the teeth clean reduces chronic inflammation in the gums. Studies show that people with poor teeth hygiene have higher bowel and other cancer as well as benign prostate hyperplasia (BPH) as well as other inflammatory related diseases such dementia, heart attacks and strokes.
Eat more unfermented soy products such as soy milk, tofu and edamame has been linked to a reduced risk of prostate cancer. Fermented soya products such as miso and tempeh can help reduce chronic disease and other cancers. Caution must be taken with concentrated soy extracts in supplement form as these could cause abnormal hormonal changes which could increase breast and prostate cancer progression.
Avoid cloves and spearmint extracts. Not all phytochemicals are beneficial so when considering a supplement, make sure they have been evaluated for safety and effectiveness in ethically approved scientific trials such as the ones mentioned above. Some manufacturers add very strong polyphenol extract from cloves and spearmint which can over-ride antioxidant pathways and have significant hormonal effects which could do harm. In general, avoid supplement with claims of research based on a quick google search rather than formal randomised clinical trials.
Be careful with vitamin A & E supplements. Deficiency of these vitamins is still common in developing countries but in the west, this is rare. A number of studies giving vitamin E and or A supplements have actually reported an increased risk of cancer of the lung, skin and prostate. These vitamins are direct antioxidants which can override oxidative pathways as opposed to natural phytochemicals which improve antioxidant and immune efficiency
Omega fatty acids are essential for vital biological, immune and inflammatory pathways, yet western diets are noticeably deficient in them. We certainly should be eating more oil rich foods such as nuts, flax, avocados, pumpkin and chia seeds, and as well as seafood including algae, seaweed, mackerel, sardines and other oily fish at least three times a week. Boosting omega three intake with supplements does not, however, seem to be a good idea as evidence from two large studies has suggested they could increase the prostate cancer risk. Their negative effect more-likely relates to excess vitamin E intake which is used as a preservative.
Consuming adequate calcium via both diary and non-dairy foods reduces bowel cancer risk. A recent large USA survey also suggested that men who included some diary in their diet also had a lower risk of heart disease. Very high intake of dairy products, on the other hand, has been linked to a slightly higher risk of prostate cancer and weigh gain. It is clear that, despite popular misconceptions, moderate amounts of milk in tea, and coffee clearly do not increase cancer risks, as do not fermented cheeses and yogurt.
So, in conclusion, although we cannot completely eliminate the risk, we can do a lot to reduce the chances of contracting cancer as well as other chronic diseases, premature aging and death. For those of you who have read to the end of this article (well done!) you may be interested in my book “How to Live” which provides more in-depth explanations of how and why lifestyle interacts with cancer disease and effects longevity.