Cancer Prevention: Diet Tips from An Expert

cancer prevention

Eating better to combat the risk of cancer has no downside and is well within our control. This post from Goop shares cancer prevention diet tips from a nutritionist.

Over half the population will be diagnosed with cancer at some point in their lifetime, the newest studies tell us. While many factors contribute to the data, it’s undeniable that lifestyle—including food—plays a major role in both reducing risk of contracting the disease and improving your chances of surviving it. As London nutritionist Adam Cunliffe points out, there’s not much to lose from adopting a diet designed to combat cancer; at worst, it contributes to weight loss and improved energy, and at best, it keeps a terrifying diagnosis at bay. Below, he breaks down what we know today about cancer and diet, and details common-sense practices you can start using now to reduce your risk.

A Q&A with Adam Cunliffe


What does the major research tell us about diet and cancer?


One in two people will now get a cancer diagnosis in their lifetime, the newest public-health information tells us. Not long ago, the data was one in three—a shocking difference. Such a drastic change points to the fact that lifestyle is at least contributing to the increased risk.

It is estimated that a third or more of cancers are related to our diet. This can be related to foods that we aren’t eating enough of, such as fresh fruits and vegetables, or things we might eat too much of, such as salt, sugar, and refined carbs. Fortunately, with the right information, diet is one risk variable that’s entirely within our control.


Can we quantify the risk reduction associated with a healthy diet?


It’s difficult to put a number to the diet factor in cancer, because so many other lifestyle and genetic factors are mixed up with risk. Plus, there’s always the random mutation effect—you could do everything right and still get unlucky.

That said, based on the best estimates, we think improved diet could reduce cancer risk by roughly a third. If we add to this, stopping smoking, avoiding excess stress, keeping physically active and avoiding high pollution levels, we can actually reduce risk dramatically. We are also confident that eating better has no downside—it’s something all of us can do right now to be healthier and feel better. If it could also help prevent a dreaded diagnosis, all the better.


What are the distinctions between preventative and curative foods?


Eating to support a strong immune system can be preventive in the sense that cancer may not occur in the first place, but it can also be ‘curative’ in sense that cancer may arise but be eliminated before it ever has a chance to take a hold. We know that cancer cells frequently form in healthy people, but our immune cells promptly destroy them. It’s the reason that more men die with prostate cancer than ofprostate cancer.

Even if cancer does get a grip in our bodies, we can inhibit its rate of growth and spread by eating an anti-cancer diet. While very few ‘cures’ (remissions) have been recorded following diet-only interventions, a notable case is documented in an individual who had complete remission from advanced cancer after self-medicating with high doses of green tea and pineapple. It could be argued that this was one of the rare ‘spontaneous’ remissions, but both green tea and pineapple are known to inhibit cancer cell growth (the anti-cancer potential of the epigallocatechin gallate in green tea and bromelain in pineapple are current cancer therapy research areas).

In conventional medicine, it’s heresy to say that a diet can cure cancer, because although there may be a few cases, oncologists are rightly worried that people would forego conventional treatment in favor of a diet-based program that may not be as effective. I don’t advocate for food-only cures, and recommend that everyone who has been diagnosed move forward with the advice of their oncologist, but I do believe that as a supplement to conventional treatment, diet is vital. For many people, diet is the first defense for keeping energy up, because body wasting is one of the worst side effects of many conventional cancer treatments. Most treatments involve breaking down parts of your immunity, so I’m particularly concerned with keeping up micro-density to support the immune system.

Adam’s Advice on What to Avoid


The most basic, but often overlooked thing we can do to help reduce cancer risk, is simply to avoid eating too much. Being overweight or obese is associated with increased risk of many cancers. Losing weight and maintaining a healthy weight reduces this risk significantly—I recommend using BMI or body fat percentage as a gauge:


  • Ideally, keep your BMI (a calculation based on height and weight that anyone can do) below 25-26; if you’re much above 26, you start to be at risk for cancer. As your BMI rises, your risk increases disproportionately; above 30, it’s quite dangerous, and above 35 even more. The good news, though, is that at high BMIs (over 30, for example) even a small change could lead to a major reduction in risk.
  • Body fat percentage can be measured with any fitness trainer (it’s done using a special machine or scale), and while they may look at very low body fat percentage for ideal physical fitness and physique, anything below 30% for women and 25% for men will keep you in a very healthy range for cancer risk.


Processed and packaged foods tend to be high in salt, sugar, and poor-quality fats, all of which fall into the ‘increased risk of cancer’ category. Excess intake of salt, in particular, is associated with stomach cancer. Additives are safety tested on small animals, one animal and one compound at a time; since humans live much longer than these animals, and are often exposed to a combination of toxins, the tests reveal little about possible health effects on us. The best way to avoid them and decrease your risk is to cook at home with fresh ingredients.


  • As an easy rule of thumb: Anything that’s designed to last a really long time is likely preserved with nitrates and salts. For those foods, keep serving sizes to a few times a week and leave a few days between servings to give your body processing time.
  • Cheap packaged foods are often hiding cheap oils. An important marketing trick to keep an eye out for is packages that say “made with olive oil”—often, a close examination of the package reveals that the product is made with 65% corn oil and 2% olive oil.
  • Make your food yourself. Natural foods contain all the salt you need nutritionally, so when you’re cooking at home, don’t add salt in the kitchen and instead leave some on the table for taste. That way, the salt lives on the surface of the food, and hits the tongue immediately, rather than getting lost in the recipe.


Excess consumption of sugar leads to obesity, which in turn increases cancer risk (see above), but sugar can also promote the growth of cancer, as cancer cells preferentially use glucose from sugar as an energy source. Insulin, which we produce in response to eating sugar, can promote the growth of cancer.


  • Restrict eating sweets, candies, and anything with high-fructose corn syrup to once or twice a week, and avoid habitual sugar, like soda. This is especially important for kids.
  • Try to reduce consumption of starchy carbohydrates like pasta and bread, which become sugar in your blood once they’ve been digested. Cancer cells prefer to use glucose as an energy source, so this is particularly important with early stage cancer, as you want to keep from feeding cancer cells their favourite food.


This form of fat is pro-inflammatory, and since chronic inflammation of tissues can lead to cancer, is best avoided. Omega 6 primarily comes from corn and sunflower oil, so where-ever possible, replace those oils with cold pressed olive oil.


  • Read packages carefully for corn and sunflower oil—they’re often hiding in salad dressings, or foods packed or canned with oils.
  • Balance the effects of omega 6 oils in the diet by increasing omega 3 fat intake through eating fish or taking fish oil supplements. I recommend fish oil for most people, but it’s important to have a high-quality product—look for high EPA content (at least 700 mg per capsule) and high DHA content (at least 500 mg per capsule). Just remember to stop taking it a few days before you have any kind of planned surgery, as it can make blood run thin.


This is a big subject, so to keep things simple, I like to think of red meat vs. all other meats. Red meat (which includes lamb, beef, and pork) has bad press with respect to cancer, particularly colon cancer, but the story is complicated. While it’s true that studies suggest red meat consumption is correlated with increased risk of colon cancer, it is also true that if you exclude processed red meat (pies, packaged foods, cured and smoked meats including bacon and ham) and only consider quality cuts of beef, pork, and lamb, the risk is much smaller. If you go further and select meat from grass-fed, organic sources which you prepare yourself, the risk is even lower.


  • Choose organic, free-range poultry and fish or vegetable-based proteins most often.
  • Keep red meat consumption to twice weekly, and whenever possible, prepare it at home.


Interestingly, modest intakes of alcohol are associated with less disease overall than a zero alcohol intake. However, excess alcohol consumption has been linked to cancers all along the digestive tract starting at the mouth, and is probably best known for causing liver problems including liver cancer.


  • Keep alcohol consumption to one or two drinks per day. The occasional 3-4 glasses is acceptable for a special occasion, but not on a regular basis.
  • The liver detoxifies alcohol in the body, so give it a few days rest from alcohol on a regular basis to ensure you are not straining it.
  • While most health professionals will say that it is purely the units of alcohol you drink that create risk, there is good evidence pointing to the fact that that wine, and red wine in particular, poses less risk than spirits or beers.

Adam’s Advice on What to Increase


Every cell in the human body is essentially a little pouch of water. When we are dehydrated at the cellular level, then the chemical processes in the cell don’t work as well. While there is no direct evidence that cellular dehydration causes cancer, it does cause cellular stress, which can lead to inflammatory responses that may be implicated in the early stages of cancer. Staying well-hydrated by drinking plenty of water and dilute juices ensures proper cellular function.


  • The actual amount you need to drink will vary according to many factors including your size and the temperature around you to your sweat rates, but the simple way to know if you are properly hydrated is to check the color of your urine. It should not be darker than pale straw colour.
  • My personal feeling is that two common additives to public water supplies, chlorine and fluoride, should be avoided where possible for many health reasons, including some research that links chlorine to breast and bladder cancer. If possible, filter out or avoid these additives, so much the better, particularly if you have babies and children in your household.


The high antioxidant content of many plant-based foods is protective of cells at the level of DNA, mopping up dangerous free radicals that can damage our genes. In addition, there are a growing number of molecules being discovered in plants that either inhibit cancer formation or growth, or that are directly toxic to cancer cells. To maximize the benefits of fruit and vegetables, eat a wide variety.


  • The five portions a day rule should be taken only as a starting point—evidence suggests that cancer risk reduction keeps rising up to nine or ten portions a day.
  • Juicers and blenders are a great way to increase fruit and vegetable intake, but it’s worth being aware that blended fruits, in particular, can be fattening if smoothies are taken to excess. I recommend eating the whole fruit (or at least blending the whole fruit, as opposed to the juice), as the fiber will naturally slow you down.


Colon cancer risk does seem to be reduced by maintaining fiber intake, but this may be due to the other nutrients in the high-fiber foods such as antioxidants and inositol. In theory, good fiber intake should prevent constipation and reduce colon cancer risk. In practice, this effect varies a great deal from individual to individual, so ‘know thyself’ with respect to fiber: Added bran, husk and whole grains may be fine for one person, but an irritant to the gut of the next, or cause bloating or gas and so be unsuitable for the next.


  • Staying well hydrated and physically activate is often a better way to stay regular than overdoing the whole grain.
  • If your intake of fruit and vegetables is good, extra ‘high fiber’ foods are usually not necessary.


High in vitamins, minerals, polyphenols and glucans, onions, sprouting broccoli, watercress, pineapple, seeded black grapes, avocado, green tea, blueberries, papaya, walnuts, Brazil nuts and shitake and reishi mushrooms will all lower the chances of developing not just cancer but a range of other diseases including heart disease, if eaten regularly. Variety is key: Eat a wide selection of them for maximum effect.


    • Though it’s not clear exactly which molecule or compound is causing this effect, it is becoming evident that coffee has a protective effect against liver cancer.
    • A good rule of thumb for superfood intake is to pack as many different colors, textures, and tastes (including bitter) onto your plate as possible.


The below have good scientific backing for their effectiveness.


      • Most people are low or deficient in vitamin D—and a regular supplement of vitamin D3 plus calcium has been shown in one study to decrease cancer incidence by a massive 75%. Even people who live in sunny regions may want to supplement: Unless parts of your torso and upper arms exposed to the sun daily, you’re not likely getting enough (your doctor can measure your vitamin D levels precisely). We used to just look at vitamin D and think of bone health, but the contemporary understanding is that all cell replication and cycling is hormonally controlled, at least in part, by the amount of vitamin D in the body; since cancer is a problem with cell cycling, vitamin D is an important factor.
      • Other supplements such as sulphorophane, bromelain, EGCG (from green tea) grape seed extract, curcumin, beta glucans and inositol hexaphosphate, all have good scientific evidence to be effective anti-cancer agents. Watch out for beta carotene supplements, though, which may actually be risky, as they have been shown to increase risk of lung cancer in smokers.

Source: 5 Cancer-Fighting Foods—Plus What to Avoid | Goop

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