Studies: Both Plant and Animal Proteins Are Protective Against Cancer

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by Nils Osmar. Updated February 19, 2022

Plant foods can be highly protective against cancer. But protein from some types of animal based foods appears to speed up the growth of cancer. Should we therefore avoid all animal proteins if our goal is to stay cancer-free?

It may be good to avoid some animal products. For example, proteins from casein (milk) and from processed meat are particularly problematic. But protein from other animal sources (including fish and poultry) are highly protective against cancer.

The way the food is prepared (heating methods) is also an important factor.

Processed Meat is Carcinogenic

According to an article published by the Osher Center for Integrative Health, processed meat is the worst offender. But many studies fail to differentiate between processed and fresh/unprocessed meat. this one does. It states: “The link between cancer risk and consumption of processed meats is well supported in the literature.”

Fish and Poultry are Protective Against Cancer

… but the skin on poultry can be a problem, depending on the cooking methods. According to the article:

:”Higher consumption of fish has been associated with decreased risks for all of the following cancers: esophageal, breast, ovarian, colorectal, and liver. .. .A meta-analysis of prospective cohort studies supported a higher consumption of fish (dietary marine omega-3) to decrease the risk of breast cancer 45. A 50% decreased risk was observed for every 1 gram per day intake of marine omega-3. However, no significant association was seen with plant based dietary omega-3. … The anti-inflammatory properties of omega-3s were also found to be beneficial in reducing the risk of liver cancer (50). Liver cancer risk was reduced by 6-18% with a 1-2 servings per week intake of fish respectively (51).”

“Poultry… may lead to a decreased risk of cancer. A meta-analysis looking at poultry intake and colorectal cancer showed a significant inverse association with at least a 50 gram (1.75 oz) per day poultry intake (27). The incidence of esophageal cancer and lung cancer were also decreased with poultry intake (10, 19)… There was one study looking at the post-diagnosis diet of over 27,000 men diagnosed with prostate cancer which found an increased risk of cancer from those eating chicken with the skin on (28). This increased risk is likely secondary to the formations of HCAs and PAHs from high-heat cooking.”

Eggs and Dairy are a Mixed Bag

  • The authors state that dairy has both “negative and some positive associations with risk for cancer.”
  • Probiotics from dairy products, calcium, vitamin D, and CLA all appear to have protective effects. But IGF-1 and phosphorous from dairy may promote the development of cancer.
  • Higher consumption of eggs is associated with an increased risk of prostate cancer.


The authors conclude that

“The over-arching claim to avoid all meat and animal products is not warranted. You do not need to be vegan to lower your risk for cancer but you do need to consume a lot of plant foods. After reviewing recent research the risk versus benefit of animal foods varies quite a bit depending on the type of animal protein and the way it is prepared.”

Another important conclusion is that the drawbacks of eating (some types of) animal products can be ameliorated by eating a lot of vegetables (which are full of beneficial anti-cancer molecules, including an array of natural antioxidants) along with the animal foods. (Carnivorous diets such as the one advocated by Paul Saladino – which have zero, or almost zero, plants in them – could end up promoting cancer for this reason, if the authors are correct.)


The authors’ recommendations include:

  • Including a variety of colorful fruits and vegetables in your diet.
  • Varying protein sources, and eating beans, lentils, nuts, seeds on a regular basis.
  • Eating fish 2 or more times per week; the fattier the better.
  • Eating poultry without skin.
  • Limiting eggs to 1 or 2 times per week; soft and hard boiled will be a better option than scrambled or fried. 
  • They suggest avoiding eggs completely if you are at high-risk for breast, ovarian, and prostate cancer.
  • Limiting red meat to once a week or less and avoiding cooking at high temperatures.
  • Buying meat from 100% grass-fed or pasture raised animals to avoid the pesticides, herbicides, hormones and other toxins found in meat from factory farms.
  • Keeping the heat below 400 degrees Fahrenheit (200 degrees Centigrade).
  • “HCA formation can also be substantially decreased by increasing the frequency of flipping during cooking; limit the amount of time you leave the meat on the heat surface”
  • Choosing cooking methods such as steaming, poaching, stewing
  • Combining colorful vegetables with your meats to reduce the negative effects of heme iron.

What I’m Doing

  • I stopped eating processed food years ago, including heavily processed meat.
  • My current diet is around 60 percent animal-based and 40 percent plant-based by volume.
  • The plant-based foods that I eat regularly include fermented and non-fermented purple cabbage, fermented beets, peas and mushrooms (both high in spermidine), root vegetables, carrots, garlic, onions, tomatoes, and some beans and lentils.
  • I do eat some dairy, but I try to avoid pasteurized milk, instead drinking raw milk products (which have been tested and found safe for e coli) or fermented dairy (plain yogurts and kefirs, which I make myself).
  • I eat lot of fish, along with some poultry, eggs, red meat and occasional organ meats. I cook them over low heat, mainly as stews, and usually eat them along with plant-based foods. For example, I might add some broccoli, onions, tomatoes and garlic to scrambled eggs. I like snacking on colored (yellow, orange and red) peppers. I try to minimize oxalates in my diet, but some of the foods I eat do contain some oxalates.
  • I experimented for a while with eating a carnivore diet, which I found had some surprising health benefits, but am not currently eating strict carnivore, though I do have some carnivore meals now and then.


  • A concern the authors don’t look at in their article is the effects of mTOR activation versus AMPK.
  • In the anti-aging community, many people are prioritizing activating AMPK (the longevity pathway) and dampening activation of mTOR (the growth pathway) as a strategy for slowing aging. More mTOR activation is associated with more muscle growth and maintenance, but too little mTOR activation is associated with a danger of sarcopenia.
  • In my own case, I’m usually fasting about 16 hours a day. I activate it by intermittent fasting (skipping breakfast); sometimes eating one meal a day; and by very occasional prolonged fasting (36 to 72 hour water fasts). (Like many people in our community I’ve cut back on the amount of prolonged fasting I was doing, after some studies showing a danger of muscle loss came to light.) Exercise also activates AMPK; I exercise vigorously several times a week.

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