Why keeping healthy is all about gut instinct: Cut your risk of cancer with our unmissable series that could save your life

We cannot alter the genes we are born with — but that definitely doesn’t mean we are irrevocably set on a path we can’t change when it comes to whether or not we go on to develop cancer.

As a consultant oncologist, I have studied the causes and consequences of cancer for most of my professional life — and I am now convinced that the way we choose to live our lives, day in, day out, can make a much bigger difference to our health and wellbeing than the genes we inherited.

The more research I undertake and the more patients I see whose health has been immeasurably improved by changing their diet and lifestyle, the stronger my conviction becomes.

We cannot alter the genes we are born with — but that definitely doesn’t mean we are irrevocably set on a path we can’t change when it comes to whether or not we go on to develop cancer

That’s why I wrote my new book, How To Live, in the hope of sharing the experiences and advice based on my lifetime’s work.

And it’s not just one individual factor that counts, as I explained in Saturday’s paper, but the sum of all the little choices that we make every day over the years. The food we eat (and how we prepare it) plays a very significant part in our health.

More and more studies are now linking poor gut bacteria with the risk of several cancers — both in and outside the gut — which is why, as we continue our exclusive series this week, today I’ve chosen to focus on our digestive systems.

What’s more, poor gut health doesn’t just cause problems in your digestive organs — it’s the cornerstone for many other serious diseases in the rest of the body, including diabetes, obesity, Parkinson’s disease and arthritis.

(And that’s not to mention bloating and indigestion, problems with bowel movements, low mood, sleep disorder and even depression, which can also be rooted in poor gut health)

Based on the latest research, I’ll explain just why your gut health matters and show you practical ways to build a thriving community of good gut bacteria that can help you reduce your risk of cancer and other serious diseases. 

The process of digestion starts in the mouth, home to hundreds of species of bacteria. 

The bacteria in and on our bodies — and particularly in our digestive systems (or microbiome) — can roughly be divided into ‘bad’ (those that cause infections such as food poisoning or cholera and typhoid) and ‘good’ (bacteria which prevent the growth and spread of disease, improve overall immunity and help to reduce chronic inflammation, which occurs when our bodies mistakenly react as if they are permanently under threat from disease).

Good bacteria are generally referred to as probiotic bacteria and include the lactobacillus and Bacteroidetes groups, linked with numerous health benefits. (I’ll look later at ways you can boost your good bacteria.)

However, poor dental hygiene — caused by not brushing your teeth or not flossing correctly — can upset the balance between the two, leading to a build-up of harmful bacteria, causing gum disease and tooth decay.

Chronic inflammation of the gums (or gingivitis) is linked to a higher risk of chronic diseases elsewhere in the body, particularly dementia, diabetes, heart disease and emphysema.

In terms of cancer, we saw on Saturday how two studies analysing more than 100 samples of healthy and cancerous bowel tissue found that DNA from bacteria commonly found in dental cavities was also present in bowel cancer tissue — but not in normal, healthy cells.

This led researchers to conclude that bacterial DNA from the mouth had travelled through the body, interacting with and being absorbed into gut cells, causing them to become cancerous and leading to bowel cancer.

These days we read a lot about why we need strong, healthy colonies of good bacteria.

And rightly so — I cannot stress enough how important it is to cherish and feed your good bacteria because they have a vital role to play in keeping your immune system in mint condition. 

This is key to helping our bodies detect and destroy early cancer cells more efficiently as well as any carcinogens in our food and environment, as I explained in Saturday’s paper.

It’s also well established that poor gut health contributes to numerous digestive problems including bloating, irritable bowel syndrome , diarrhoea, food allergies and intolerances.

Research now shows that a depleted colony of good bacteria leads to damage or thinning in your gut walls, weakening the barriers that normally prevent toxins (including carcinogens) from getting into the blood stream.

As a result, these toxins and bacteria can cause inflammation all over your body. This is commonly known as ‘leaky gut syndrome’. But it doesn’t end there.

An inflamed gut wall also makes the body less efficient at absorbing the vital nutrients it needs from food — so over the long term, this can cause deficiencies in vitamins A, D and zinc, all of which have important roles to play in our immune system’s defence against disease and cell damage.

Dining out? Then don't overeat

Eating out and staying away from home can play havoc with your microbiome, as you are more likely to consume more alcohol and dine out on rich or unaccustomed foods.

To look after your gut when dining out or going away, try not to overeat and try to have alcohol-free days when you are on holiday. 

Eating lots of fruit and vegetables and drinking plenty of water should keep your bowels regular, but if you are constipated you could try taking some extra flaxseed (also known as linseed). 

In addition, many people, including me, swear by the protective benefits of a good-quality probiotic supplement, starting a couple of days before travelling.

This is why a wide range of serious diseases in other parts of the body — including dementia diabetes, arthritis and obesity — can either be caused or aggravated by poor gut health and chronic inflammation.

There is also emerging data to suggest it is a ‘trigger’ for type 1 diabetes — because the body gets confused by toxins in the blood stream and starts inadvertently attacking its own pancreas.

This chronic inflammation also helps to explain why the tumours associated with poor gut health are not just restricted to several types of bowel cancer.

In addition, scientists now know that healthy colonies of good gut bacteria use phytochemicals to produce a fatty acid called butyrate that helps protect the cells lining the colon from genetic damage.

Not only this, but butyrate also kills established colon cancer cells before they get a foothold — yet another reason why eating a diet high in phytochemical-rich vegetables, fruit, herbs and spices is a key way to look after your gut health and cut your cancer risk.

The cancer-fighting results of feeding your good gut bacteria with phytochemical-rich foods was recently illustrated by an exciting academic study that I was involved with at the Primrose Oncology Research Unit at Bedford Hospital.

Known as the Pomi-T study (after the extracts we tested: pomegranate, broccoli, turmeric and green tea), it is to date the world’s largest and probably most respected trial evaluating the impact of phytochemical-rich foods.

It was clear from our trial, which involved 203 men with diagnosed prostate cancer, that taking a gut-friendly probiotic supplement rich in phytochemicals not only reduced inflammation in the gut but also slowed the progression of the prostate cancer in those who took it, compared with those in the control group who did not.

This is one of the many reasons I am so excited at how many ways there are, based on the latest science, to take control of our own health — starting with looking after our guts. It really does help to look at your diet again and think about ways to eat for your gut.

I’ll look in more detail at which supplements are helpful to take in tomorrow’s pullout.

Going organic really can be better for you

Pesticides and other chemicals make it into our food chain without us realising it — and some can be very damaging.

They are used to control insects, weeds, fungi and bacteria and help to ensure we can produce enough food to meet demand.

But inevitably they also make it into the food chain — and some (organochlorines and organosulfates) can cause cells to mutate, while DDT, chlordane and lindane are tumour promoters.

The pesticide MXC was developed after the ban of DDT but tests have also shown that this stimulates the proliferation of breast cancer cells. Its use is falling, but others with potential risks are replacing it.

Pesticides and other chemicals make it into our food chain without us realising it — and some can be very damaging

Some insecticides also contain arsenic compounds still in common use which have been classified as carcinogens by the International Agency for Research on Cancer .

Meanwhile, chlorothalonil, a fungicide used on trees, vegetables and agricultural crops, has been classified as ‘likely’ to be a human carcinogen.

Non-Hodgkin’s lymphoma, a cancer of the lymphatic system, has previously been associated with exposure to glysophate, a herbicide commonly used as weedkiller.

Although the evidence of risk is small outside farm workers, it’s certainly worth trying to reduce your intake of pesticides over time by buying organic, growing your own fruit and veg and making sure you wash any shop-bought produce thoroughly before you eat it.

Organic food cannot be completely free of synthetic chemical residues, due to product and environmental pollution, but organic agriculture avoids synthetic fertilisers and pesticides, and instead uses holistic methods of weed and pest control such as long crop rotations, natural predator insects and insect traps.

Organic meat also has lower levels of other potentially harmful contaminants, as livestock is not given growth hormones or antibiotics, so it is worth buying organic whenever you can. 

Protecting your ‘good’ bacteria should be top of your to-do list when it comes to focusing on how you can cut your cancer risk by improving your gut health. 

You can either do this by ‘topping them up’ with other living microbes called probiotics or by ‘feeding’ them with compounds that strengthen them. 

Here are my eight top ways to protect your core asset — and reduce your risk of a number of cancers. 

Say yes to chocolate

A square or two of dark chocolate may seem an indulgence but could also help towards a gut-friendly diet rich in phytochemicals. 

Chocolate contains many polyphenols, as well as theobromine — a vasodilator which increases heart rate, lowers blood pressure and boosts brain levels of the mood-enhancing chemical seratonin. 

One study found those who regularly eat dark chocolate tended to have lower blood pressure.

What about milk and dairy?

Many people wonder if dairy is good for them. This is partly because cow’s milk is a common cause of allergies and digestive problems, though these can usually be diagnosed with tests or elimination.

But there are some reports that milk and dairy products are carcinogenic.

I think it’s likely that the risks of moderate milk consumption have been overemphasised.

It is often quoted that Asian cultures have a low cancer rate as they don’t drink much milk, but other factors could account for this, including being more active and eating more fruit and vegetables.

There are no robust randomised trials linking milk with an increased cancer risk. In fact, higher milk intake has actually been found to reduce bowel cancer risk.

Analysis of 12 large studies showed no significant increase in ovarian cancer risk in those who consumed a moderate amount (one or two glasses). However, more than two glasses of milk a day did increase the risk in relapsing after treatment for breast and ovarian cancer.

Similarly, a large study recently linked high calcium intake (from milk and supplements) with a raised risk of prostate cancer, but concluded one to two glasses was not associated with increased risk.

As we’ve seen, kefir and live yoghurt are among the healthiest ways to consume dairy products (so long as you are not lactose intolerant) because they contain probiotics as well as being rich in protein, vitamins, omega fats and energy.

Do you feel as though you can’t face the day without a cup of coffee in your hand? If so then you can rest easy — at least as far as cancer is concerned.

Research shows that moderate consumption of coffee is actually good for you in terms of cancer and can reduce your risk of prostate, liver, womb cancer and some cancers of the throat and mouth.

This is despite the fact that the coffee beans are roasted — a process that produces moderate levels of acrylamides.

Baking, grilling or roasting foods at high temperatures produce these toxic compounds, linked to an increased risk of cancers.

Do you feel as though you can’t face the day without a cup of coffee in your hand? If so then you can rest easy — at least as far as cancer is concerned File

But the evidence of recent studies implies that this is substantially outweighed by the benefits from all the cancer-protective phytochemicals in coffee.

As for tea, the great British cuppa is not just a national treasure, it can also help to lower your risk of cancer.

Both green tea and the black stuff we’ve been drinking in the UK for hundreds of years contain high quantities of numerous polyphenols and it may surprise you to learn they both come from the same plant.

When the leaves of the Camellia sinensis plant are dried, they are fermented and oxidised to form the black tea we are familiar with. Green tea is unfermented and merely steamed.

Tea polyphenols are important because they have been shown to block an enzyme which tells cancer cells to proliferate faster and bypass a process called apoptosis, which is a pre-programmed self-destruct mechanism by which our body gets harmful cells to destroy themselves.

They also have excellent anti-inflammatory properties.

Despite these positive effects on biological pathways, not all human studies have linked a daily cuppa or two with a lower risk of cancer.

In fact, the large Japanese Ohsaki National Health Insurance Cohort Study reported that tea consumption was not associated with lower cancer levels, and a large Cochrane review concluded that there was insufficient evidence for a benefit or risk, although quality of life seems to be better in tea drinkers.

However, I am convinced of the anti-cancer benefits of tea drinking, partly from studying other data and partly because of a big research project that I was involved in.

Our research team at the Primrose Research Unit at Bedford Hospital undertook a 155,000-person analysis, which performed the world’s largest specific analysis of tea, following participants for 12 years. We were able to prove that drinking two to three cups of tea a day reduced the prostate cancer risk.

Interestingly, there wasn’t a benefit for those tea drinkers who added sugar to their cups, however.

Population studies have shown that people who drink tea regularly have lower risks of arthritis as well as Parkinson’s and Alzheimer’s, which is thought to be due to a reduction in the build-up of harmful amyloid in brain tissue.

The protection from heart disease and stroke by green tea (although not black tea) is thought to come from its ability to lower LDL cholesterol. Finally, regular consumption of tea has even been shown to improve bone health and reduce the risk of developing arthritis, as well as improving exercise performance.

So this is why, as a doctor, I wholeheartedly prescribe you to put the kettle on and treat yourself to a cup of your favourite brew!

Changing diet helped me cope with chemo

Julie Woodgate, 46, is a business analyst who lives near Windermere in the Lake District with her husband Martin Scovell, 60, a marketing executive. 

Julie, who has a grown-up stepdaughter, changed her diet and lifestyle to help her to deal with chemotherapy and surgery after being diagnosed with stage 2 breast cancer eight years ago. Julie says:

When I found out I had breast cancer I was determined to give myself the best chance I could of recovering from my treatment and living to enjoy as many more years as possible.

So I was keen to try any diet and lifestyle changes that might help me to cope with the side-effects of eight rounds of chemotherapy after being diagnosed with stage 2 breast cancer when I was only 38 in 2012.

On Professor Thomas’s recommendation, I ate much less red and processed meat — at first this was quite hard because I ate meat most days. Giving up my favourite, sausages, was the biggest sacrifice. I also used to love sweets — like a bag of pick and mix — but I stopped eating those too and cut right back on alcohol.

Instead, I drank lots of water, at least two and a half litres a day, and this helped to flush out the toxins in my chemotherapy drugs and reduce the severity of the nausea, hot flushes, constipation and terrible fatigue.

I also made a massive effort to eat lots of green, leafy vegetables. I took some phytochemical supplements and added turmeric to the recipes I prepared to maximise the amount of extra benefits I could get from all the polyphenols and other healthy plant chemicals.

Vegetables have now become such a part of my life that I’ve got my own veg patch where I grow purple-sprouting broccoli, peas, cauliflower, chard, beans and sprouts, which have the added benefit of being free from pesticides.

Another massive change was taking up exercise. Before my diagnosis, I didn’t do much but now I do three sessions a week with a personal trainer.

It turned out that, like the actress Angelina Jolie, I had inherited the BRCA gene mutation which made me likelier to develop breast cancer and at an earlier age. After studying my options, I chose to undergo a double mastectomy to minimise the chances of my localised cancer spreading to both breasts.

My cancer has been in remission since 2013 but in the hope of giving myself the best chance, I chose last year to also have my ovaries removed as a preventative measure. This has the effect of reducing the amount of oestrogen your body produces, which in turn lowers the risk of breast cancer returning.

Now I really live in the moment and I enjoy my healthy lifestyle. My stepdaughter’s expecting a baby soon — and I’m looking forward to being a granny. 

Extracted by Judith Keeling from How To Live by Professor Robert Thomas, published by Short Books at £14.99. © 2020 Professor Robert Thomas. 

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