Applying the Precautionary Principle to Nutrition and Cancer

Applying the Precautionary Principle to Nutrition and Cancer

By Susan Levin, M.S., R.D., C.S.S.D.

Research continues to show, time and time again, that plant-based foods reduce the risk of cancer and strengthen the chance of survival after diagnosis.

While more research is needed in this area, we now have a set of six precautionary principles to reduce the risk of occurrence:

1) Avoid dairy products to reduce risk of prostate cancer.

2) Limit or avoid alcohol to reduce the risk of cancers of the mouth, pharynx, larynx, esophagus, colon, rectum, and breast.

3) Avoid red and processed meat to reduce the risk of cancers of the colon and rectum.

4) Avoid grilled, fried, and broiled meats to reduce the risk of cancers of the colon, rectum, breast, prostate, kidney, and pancreas.

5) Women should consume soy products in adolescence to reduce risk of breast cancer. Breast cancer survivors should consume soy products to reduce risk of cancer recurrence and overall mortality.

6) Eat a diet rich in fruits and vegetables to reduce risk of several forms of cancer.

Diets that center around plant sources—vegetables, fruits, whole grains, and legumes—are associated with lower cancer risk, as well as reduced risk for cardiovascular disease, diabetes, and hypertension.

Plant-based diets support a healthy weight, which in itself reduces the risk of many common forms of cancer. Especially good plant sources include cruciferous vegetables, such as broccoli, kale, and cabbage; carotenoid vegetables, including carrots and sweet potatoes; tomato products; and allium vegetables, such as onions, garlic, and leeks.

The background: Antioxidants in plants may reduce the spread of tumors and help repair damaged DNA. Some components in soybeans, green tea, turmeric, grapes, tomatoes, and other plant foods have the ability to regulate apoptosis, an important pathway for cancer prevention.

The good news? You can do no harm, only good, by eating a diet rich in plant-based foods.


Fruit and Vegetable consumption and all-cause, cancer and CVD mortality: analysis of Health Survery for England



Eating seven or more portions of fruit and vegetables a day reduces your risk of death at any point in time by 42 percent compared to eating less than one portion, reports a new study. This is the first study to link fruit and vegetable consumption with all-cause, cancer and heart disease deaths in a nationally-representative population, the first to quantify health benefits per-portion, and the first to identify the types of fruit and vegetable with the most benefit.

Dr. Greger’s Testimony Before the 2015 Dietary Guidelines Committee

In the Permanente Journal last year, the official peer-reviewed publication of our nations largest managed care organization, a “Nutrition Update for Physicians” was published, which concluded that “Healthy eating maybe best achieved with a plant-based diet,” which they defined as a diet that encourages whole plant-based foods and discourages meat, dairy products, and eggs as well as empty calorie junk. To quote their conclusion: “Research shows that plant-based diets are cost-effective, low-risk interventions that may lower body mass index, blood pressure, HbA1C, and cholesterol levels. They may also reduce the number of medications needed to treat chronic diseases and lower ischemic heart disease mortality rates. Physicians should consider recommending a plant-based diet to all their patients, especially those with high blood pressure, diabetes, cardiovascular disease, or obesity,” which of course describes a bulk of our population.

This sentiment was echoed last summer by the American Institute for Cancer Research—probably the most preeminent institution on diet and cancer risk—when they explicitly endorsed a diet revolving around whole plant foods: vegetables, whole grains, fruits and beans.

I’ve personally been eating a plant-rich diet since 1990, when Dr. Dean Ornish published his Lifestyle Heart Trial in The Lancet, angiographically proving that heart disease could be reversed with the help of a plant-based diet, opening up arteries without drugs, without surgery. If that’s all a plant-based diet could do, reverse our number one killer of men and women, then shouldn’t that be our default dietary recommendation until proven otherwise? And the fact that plant-based diets can also be effective in preventing, treating, and arresting other leading killers, such as type 2 diabetes and hypertension, would seem to make the case for plant-based eating overwhelming.

Now to the last Guideline Committee’s great credit, the 2010 guidelines were a leap in the right direction, recognizing food as a package deal. Yes there’s calcium in dairy, protein in pork, iron in beef, but because of the baggage that comes along (like the saturated fat and cholesterol), plant sources are preferable, because then the “baggage’ we get is the fiber, the folate, the phytonutrients, etc.

I would like to see the committee be more explicit, though. When “eat-more” recommendations are issued, the messaging is clear—for example, “Increase vegetable and fruit intake.” But when there’s a conflict between USDA’s dual role to protect the public while at the same time promoting agricultural products, recommendations often resort to speaking in cryptic biochemical components, such as “Reduce intake of solid fats (major sources of saturated and trans fatty acids).” How about instead, eat less cheese. Or messages like drink less soda. Eat less meat, particularly processed meat. The American Institute for Cancer Research just comes out and says it: “Processed meat like bacon, sausage, and cold cuts should be avoided.” Period. They don’t need to sell food; they just want to prevent cancer.

I am not here today on behalf of the broccoli lobby (though I’d be honored to represent big broccoli). I am not here representing any financial interest. I am here as a physician, representing the interests of the hundreds of thousands of Americans that continue to suffer and die every year from chronic disease. And you can help them by recommending a more plant-based diet.

Link to article and video and all together amazing website for nutrition information:

Whole Foods Plant-Based Lifestyle Plan to Prevent and Reverse Chronic Disease

Eat food, not too much and mostly plants” – Michael Pollan

  1. Watch Forks Over Knives, available on Netflix or on Amazon for 3.99 to rent or purchase on iTunes for 9.99 or check out at your local library, or buy DVD at
  2. Ask yourself before you put something into your body: Is this a whole food or refined?  Know the difference.
  3. Work to increase vegetables, legumes (beans, lentils & peas, non-GMO soy), fruit and whole grains.
  4. Non-gluten whole grains: brown rice, quinoa, millet, amaranth are recommended.
  5. Buy in bulk: legumes, whole grains. Buy local. Direct from farmers (look for CSA options). Stick to the periphery in the market. As for organics, be mindful of the ‘Dirty Dozen’
  6. Start the morning with oatmeal and berries using almond milk or try a green smoothie. My favorite is raw kale with frozen berries and chia seeds.
  7. Add raw seeds to your diet:  Chia, flax (fresh ground), sunflower, pumpkin, etc for essential fatty acid support.
  8. Have up to one handful of raw nuts daily.
  9. Cook staple foods (legumes & whole grains) in larger batches so you can reheat for future meals.
  10. You can have some egg-free pasta:  rice pasta (no wheat) or whole wheat but don’t overdo it.
  11. If you are craving something sweet try to go for whole fruit or 1 small square of dark dairy free chocolate
  12. Avoid all white flour products, refined sugar and processed foods (AKA “food-like” products or junk)
  13. Get the junk out of the house! Or at least don’t buy it again so there are no easy temptations lying around.
  14. Avoid or minimize all dairy and animal products especially if from factory farms.
  15. Drink plenty of water in between meals. Wean off sodas, diet or regular.
  16. Start every morning with a glass of water,  add fresh lemon and cayenne if you like to help with cleansing
  17. Move your body daily: Pick what you enjoy most or try something new: walking, yoga, cycling, swimming, tai chi, barefoot style running.
  18. Practice breath awareness and meditation, this will help with your cravings and stress management
  19. Sleep 8-10 hours a day, this is when the body heals.  Trouble sleeping?  Then avoid caffeine after lunch, avoid late night TV, do not over eat and try to eat dinner at least 2-3 hours before bedtime
  20. Take Vitamin D3 in the winter months, 2000 IU daily with food to strengthen immune system and prevent the winter blues (seasonal affective disorder)
  21. Take a Vitamin B12 supplement or eat more organic vegetables without washing them too well. or B Complex daily (without standard synthetic folic acid)
  22. Eat 3-4 servings of seaweed weekly for adequate iodine which is needed for thyroid function. My favorite is Dulse, or try Nori sheets used for sushi. Or can take 1 kelp tablet daily
  23. The leading causes of death in this country are heart disease and cancer, both of which are for the most part, preventable if you follow a whole foods plant-based diet.  And now we know that heart disease can be reversible on a strict low fat completely plant-based diet (vegan)           (Read Prevent and Reverse Heart Disease by Caldwell Esselstyn, MD )
  24. H=N/C  (Health = Nutrients/Calories) The Standard American Diet (SAD) is nutrient poor and calorie rich. Increasing the nutrients increases our health. Decreasing the calories increases our health.  Focus on nutrient dense foods that are naturally lower in calories over calorie rich and nutrient poor foods.  (Read Eat to Live by Joel Fuhrman, MD)
  25. Practice eating to 80% fullness. (‘Hara Hachi Bu’) Eat slowly & mindfully. Take a few soft belly breaths before each meal to help you slow down and chew well.  Caloric restriction increases longevity (Read The Blue Zones Dan Buettner)
  26. Be mindful of the P/a ratio = Plant to animal ratio. Increasing plants and decreasing animal products has been shown to increase longevity and prevent chronic disease.
  27. Avoid the Pleasure Trap: We are designed to seek pleasure, avoid pain and be as efficient as possible in this process. What killed humans most often during most of the time on this planet is famine (starvation). Our brains are still designed to survive famine. It does this by rewarding us when we eat more caloric dense foods. (fat, sugar) That is why we feel temporarily pretty good after eating meat and cheese. This is because of increased levels of dopamine in the brain. (Heroin does that too!)   In modern times what kills most humans is EXCESS not starvation. Too much fat and sugar! And we can get a hold of it without any work at all (very efficient), just driving to the market to purchase compared to the day when humans would walk/run on average 10 miles a day gathering and hunting for food.  (Read The Pleasure Trap)
  28. The Gabriel Method: Diets don’t work. Instead of thinking I can’t have this, I can’t have that. Think I can have it but I choose not to. Increase the good in your life! Increase the healthy foods, let them take up more of the plate and the good will eventually win over the bad. You will put your body in a better position to heal itself. Your cravings will decrease. Your taste buds will change and you will enjoy your food more. (Watch Hungry for Change!)
  29. Acid/Alkaline: Processed foods: white flour products, sugar and animal products including dairy are acid forming in the body. Vegetables, beans and fruit are alkaline forming. Too much acid forming foods causes inflammation, and chronic disease.
  30. Don’t worry about protein! As long as you are eating mostly whole foods you will likely meet your protein requirement. If you feel you are not getting enough, increase beans, try tempeh! Add hemp seeds. Your requirement for protein is 0.8 grams/body weight in Kilograms. Do the math.
  31. Remember oils are processed and don’t exist in nature for consumption. It takes 44 olives to make 1 tablespoon of olive oil. 16 ears of corn for 1 tablespoon corn oil and 3 feet of sugar cane for 1 teaspoon of sugar! Keep it whole and unprocessed and your body will respond. Check out for whole plant based recipes and information from Chef AJ.

Other documentaries to watch: Hungry for Change, Food Inc, Fat Sick and Nearly Dead, Forks Over Knives:The Extended Interviews.

Other booksThe China Study by T. Collin Campbell, PhD, Dr. Neal Barnard’s Program for Reversing Diabetes: The Scientifically Proven System for Reversing Diabetes without Drugs, The Pleasure Trap: Mastering the Hidden Force that Undermines Health & Happiness by Douglas J. Lisle, PhD, The End of Diabetes by Joel Fuhrman, MD, Diet for a New America by John Robbins


Getting started:,, search PlantBased-Diet-for-Beginners-How-to-Get-Started                                                                                                                                                    For the science behind plant-based diets in short educational videos: