Given that we have been taught for so long that meat and milk are necessary for human health, how could animal protein and cancer be correlated? It might be hard to believe, but the evidence that animal foods promote disease while plant foods prevent and even treat disease is irrefutable.
- What sources link animal protein and cancer?
- Animal protein turns on cancer growth; plant protein turns it off
- Don’t we need the “high quality” protein from animal products?
- How much protein should we really be consuming?
- Animal protein and cancer
- Why do other studies claim animal products are good for you?
- Why haven’t I heard this before?
- What’s the takeaway?
What sources link animal protein and cancer?
High-quality evidence that animal protein and cancer are linked comes from a wide range of reputable sources. They include but are not limited to: the World Health Organization; The China Study (funded by Cornell, Oxford and the China Cancer Institute); nonprofits like the Physicians’ Committee for Responsible Medicine; professional organizations like the American College of Lifestyle Medicine; and academic journals such as the Journal of Geriatric Cardiology, The American Journal of Clinical Nutrition, the European Journal of Epidemiology, the International Journal of Epidemiology, and the International Journal of Environmental Research and Public Health, many of which include systematic reviews and meta-analyses.
Several well-known doctors who promote plant-based diets include Dr. Colin Campbell, Dr. Esselstyn, Dr. Neal Barnard, Dr. John McDougall, Dr. Michael Greger, Dr. Dean and Alesha Sherzai, Dr. Garth Davis, and Dr. Michael Kleper. You can even find local plant-based doctors and local plant-based dieticians and wellness coaches. For more support from unbiased organizations, check out NutritionFacts.org.
Particularly compelling research comes from The China Study: Startling Implications for Diet, Weight Loss and Long-term Health (2005, 2016), one of the most comprehensive studies of lifestyle, diet and disease ever done. The results revealed that animal protein (especially meat, dairy, and eggs) is strongly linked to cancer growth.
Animal protein turns on cancer growth; plant protein turns it off
Studies by the lead researcher of The China Study, Dr. Colin Campbell, demonstrate that we can turn on and off cancer growth simply by altering the levels of protein consumed. Animal-based protein and plant protein cause very different responses in the body. Animal proteins stimulate the production of growth factors, especially insulin-like growth factor (IGF), which is linked to cancer growth. In contrast, plant proteins do not promote cancer growth.
The China Study describes how researchers have used rats in studies examining the impact of animal protein versus plant protein on cancer growth. Rats serve as an effective model because they need almost the exact same amount of protein as humans. In a study of two groups of rats, both were administered carcinogens (aflatoxin). The group fed a low-protein diet or a diet high in wheat and soy protein did not develop cancer. The group fed a high animal protein diet did develop cancer. Cow’s milk protein, casein, was found to promote cancer growth the most.
The researchers then switched the two groups. The rats switched to a high animal protein diet began growing tumors again. This is because carcinogens only proliferate in the right environment. These results indicate that even those who have a strong genetic predisposition to develop cancer can turn on and off cancer growth through nutrition.
On top of this clinical evidence, geographical rates of disease also support this conclusion. Countries that consume high levels of animal proteins have high levels of cancer. Those that consume mostly plants have low levels. When people migrate from one country to another and adopt the typical diet, they then adopt that country’s disease risk.
Don’t we need the “high quality” protein from animal products?
Misleadingly, animal proteins are termed “high quality” because their amino acids are most similar to ours. That means they can most “efficiently” be used in our bodies. According to its definition, eating human flesh would be the most “high quality” protein. Clearly, then, we don’t want to eat something just because it’s termed “high quality.”
Animal protein promotes the growth of both healthy and cancerous cells. When we eat plant proteins, our bodies can combine the incomplete plant proteins eaten at different times throughout the day to form “high quality,” complete proteins. Despite the common misunderstanding, we do not need to combine them at each meal.
How much protein should we really be consuming?
- Minimum to avoid protein deficiency: 5-6%
- To protect against cancer, we should consume only 10% of our calories from protein (about 50-60 grams per day depending on body weight and total caloric intake)
Although Western culture reverses protein as the primary nutrient, it is low protein diets that repress cancer formation. Plant foods naturally meet these protein ratios: chickpeas have about 5 grams of protein per 100 calories; spinach has about 12 grams per 100 calories. Furthermore, researchers have not linked even high levels of plant protein intake to cancer development.
- Level at which cancer foci develop in animal experiments: 12%
- Average American intake: 15-16%
- Level the US government recommends: 17-21%
According to the American Cancer Society, males in the U.S. have about a 40% lifetime risk of developing cancer, and females have a 38% risk. We also have one of the highest rates of death from cancer in the world. Adopting a whole foods plant based diet can help prevent many of these cancers.
Animal protein and cancer
Men who eat 3-4 eggs a week increase their risk of prostate cancer by 81%. Another consistent predictor of prostate cancer is dairy intake. Men who ate the most dairy products were up to 65% more likely to develop prostate cancer. Men with prostate cancer who eat 3+ servings of dairy daily having a 141% higher risk of dying from their cancer within 10 years compared to those who eat less than 1 serving a day. Consuming animal-based foods increases the blood levels of the growth hormone IGF-1 (insulin-like growth factor). Much like cholesterol levels predict heart disease, IGF levels predict cancer risk.
Percent of cases attributable to genes/family history alone:
- Less than 3%.
- Much like you can plant a seed and it won’t grow if not given the proper environment, we can reduce the risk of cancer genes being expressed by creating an infertile environment for them. Genes contributes only 3-10% of risk of most types of cancers, with lifestyle factors accounting for the remainder.
- Foods that keep estrogen levels in check: a diet high in whole plant foods and low in fat and animal protein
- Dairy – Another study found that increasing the casein in rats’ diets promoted the development of breast cancer in rats dosed with carcinogens. Women drinking 2-3 cups of cow’s milk a day (what the USDA recommends) increased their risk of breast cancer by 70-80%. Cow’s milk is full of estrogen, which helps both baby calves and cancer cells grow.
- Animal protein
Other benefits of adopting a plant-based diet include that when women reach menopause, they have fewer menopausal symptoms because there is a less severe drop in estrogen levels.
The more animal protein you eat, the higher your risk of liver cancer. In a study of rats given a cancer-causing chemical, of the rats fed a 20% animal protein diet (what most people in the West consume), 100% developed liver cancer. Of those fed a diet of 5% animal protein, none developed cancer. This study demonstrates that nutrition controls cancer development even more than chemical carcinogens.
Rates are high in North America, Europe, Australia, and wealthier Asian countries, and very low in Africa, Asia and most of Central and South America. Diets naturally high in fiber and low in animal-based foods can prevent colorectal cancer. However, fiber and vegetable intake is likely to protect us against colorectal cancer only when paired with zero intake of animal products.
Why do other studies claim animal products are good for you?
But, you say, some studies seem to show that animal products are good for you. How do we know what to trust?
Firstly, look at the study’s sponsors: Are they for-profit corporations like the National Cattleman’s Beef Association? Or are they non-profits like the Physicians’ Committee for Responsible Medicine? (Beware that some food industries have formed non-profits in an attempt to create studies that seem more trustworthy.) Secondly, look at the study’s methodology: a meta-analysis? a systematic review? a randomized trial? These are high quality methodologies.
Why haven’t I heard this before?
But if it’s so widely supported, why haven’t you heard of it until now? Unfortunately, food industry lobbying of government nutrition guidelines and medical school education is still the status quo. “Big Medicine” is not keen to delve into this research because 1) hospitals don’t profit from lifestyle changes and 2) corporations can’t patent a prescription for plant foods.
What’s the takeaway?
Animal-based foods promote cancer development. Plant-based foods protect us against cancer growth and development. Yes, you might be able to get away with consuming some animal products and not go on to develop a cancer. But to lower your risk to the greatest extent possible –