The main point on protein is that you want to consume as much of your daily protein requirements from a variety of low fat sources, such as legumes (beans, peas, lentils, soy, nuts and nut butters), deep, cold-water fish (salmon, sardines, mackerel, cod), poultry (skin removed) and whey (a milk protein.)
You don’t have to completely eliminate dairy and meat (particularly, red meat: beef, pork, lamb) from your diet to live an anticancer lifestyle, but you will need to limit the quantity you consume. Increasingly, the results of numerous studies are consistently suggesting that the most healthful overall diet (anti-cancer, anti-diabetes, anti-cardiovascular disease, anti-inflammatory, etc.) is likely the vegan diet.
Dairy and Cancer:
- Most dairy products are high in saturated fat, which we know can lead to increased systemic inflammation, increased production of cancer-causing free radicals and weight gain.
- Since the FDA approval of the recombinant Bovine Growth Hormone (rBGH), in 1994, most dairy farms in the United States inject their cows with rBGH to increase the production of their milk. rBGH not only increases the production of milk, but it also excessively stimulates the cows’ liver to over-produce a growth factor called, insulin-like Growth Factor 1 (IGF-1). Excess levels of IGF-1 have been increasingly linked to human cancer development and growth (particularly, breast, prostate and colon cancers.) The manufacturer of rBGH reported a ten-fold increase in IGF-1 levels in milk of cows receiving the hormone. IGF-1 is the same in humans and cows, and is not destroyed by pasteurization. When you consume rBGH dairy products, the IGF-1 is not destroyed by digestion and is absorbed through the bowel into the blood. (Read more about IGF-1 and dairy)
- Dairy products are high in lactose and other sugars, which increase blood sugar, insulin and IGF-1 (your liver produces IGF-1 in response to increased blood glucose and insulin.) All of these factors, when in excess, can lead to tumor development and progression (cancers love sugar…and growth factors)
- Dairy products are high in casein (casein comprises approximately 85% of milk protein, and whey protein makes up 10-15% of milk protein), which has been shown to increase tumor growth rate and metastases, in animals. It is also believed that casein may be one of the strongest cancer promoters (stimulates cancer growth) in humans, as discussed in great detail in Dr T. Colin Campbell’s international best selling book, The China Study.
- When consuming protein powders and drinks, limit or avoid those which use isolated casein as the primary source of protein. Preferentially select whey-based protein powders or drinks (studies report that whey protein may reduce the risk of various cancers, including breast cancer and colon cancer).
- Dairy products are calcium-rich. Some studies suggest that calcium intake may be linked to the development of prostate cancer.
- Consumption of dairy products can lead to lactose intolerance (affecting over 30 million adults, in the U.S.), causing diarrhea and cramping.
If you wish to consume dairy products (milk, cheese, cream, yogurt, ice cream, etc.), I recommend selecting those that are:
- organic (no hormones); they should be clearly labeled ”No rBGH” to minimize your exposure to excess levels of IGF-1
- lower fat (preferably, non-fat)
- come from grass-fed animals (producing higher amounts of omega-3 fatty acids in their milk and meat.)
Meat and Cancer:
- Most meat products (particularly, red meat: beef, pork, lamb) are high in saturated fat, which we know can lead to increased systemic inflammation, increased production of cancer-causing free radicals and weight gain.
- Most U. S. beef cattle are implanted or injected with synthetic sex hormones (estrogen, progesterone, testosterone), to stimulate growth. These hormones remain in the meat products that we consume, and it is strongly suspected that these growth stimulating hormones may be one of the key factors linking meat consumption with the increased risk of cancer development and progression in humans. (Read more about hormones in meat)
- Use of hormones is approved by the FDA for use in beef cattle and sheep. No hormones are approved for growth purposes in dairy cattle, veal calves, pigs, or poultry. (Read the FDA information on steroid hormone use in animals…they tell us it’s all quite safe)
- Diets high in red meat increase the risk of developing cancers (colorectal, lung, breast, uterine, ovary, prostate) and cancer recurrence.
- Research demonstrates that people who eat even modest amounts of red meat have a higher risk of developing colon cancer and a higher risk of dying from cancer, or any cause.
- Processed meats (bacon, hot dogs, deli meats), likely due carcinogenic nitrites, are strongly linked to the development of numerous cancers. (Read more about cured meats and nitrites)
If you consume meat products, I recommend selecting:
- organically raised (look for ‘hormone free’ labels)
- grass-fed (higher omega-3 fatty acid composition)
- non-processed
- the best animal protein choices are fish (particularly, the omega-3 fatty acid rich fish) and poultry (skin removed)
- if you are partial to red meat, select the leanest cuts, choose moderate portion sizes, and make it only an occasional part of your diet
Eggs and Cancer:
- Although the mechanisms to explain this correlation have not been identified, there are a few studies that demonstrate an association between egg consumption and cancer risk (particularly, colorectal, bladder and prostate cancers):
- A study done in Argentina found that people consuming approximately 1 ½ eggs per week had nearly 5 times the colorectal cancer risk compared with individuals consuming less than 11 eggs per year.
- A World Health Organization study analyzed data from 34 countries and determined that egg consumption was correlated with mortality from colorectal cancers.
- In a case-control study of 130 bladder cancer patients, egg consumption was found to be associated with a 3-fold increased risk of developing bladder cancer.
- A UCSF case-control study of 3127 men with localized prostate cancer found that men who ate 2.5 eggs or more a week had an 81% higher risk of developing lethal prostate cancer compared to men who ate fewer than 0.5 eggs a week on average.
- A recent study has found that consumption of raw eggs may increase your risk of infection of certain cancer-causing viruses (14% of eggs are infected by oncogenic viruses). We are not sure of the implications on humans, but this is certainly an area of concern.
70% of the calories in eggs are from fat (mainly, saturated fat) and they are loaded with cholesterol (about 213 milligrams for an average-sized egg), I recommend that you avoid or limit your intake of whole eggs.
If you really want your egg fix, opt instead for egg whites or egg substitutes (but recognize, that since we don’t know the potential mechanism to explain if/how egg consumption may lead to cancer development, egg whites may still place you at an elevated risk.)
Can Vegans Get Enough Protein and All The Required Essential Amino Acids?
Absolutely, yes!
“Complete proteins” contain all of the amino acids needed by our body to build new proteins, cells and tissues. Only animal sources of protein are complete. Non-animal proteins are “incomplete proteins” (i.e. fruits, vegetables, grains, nuts), and are typically missing one or more of the “essential” amino acids (these amino acids are not made by the body and must be obtained from our food.)
In order for vegans to get all the amino acids needed by their body, they have to consume a variety of protein-containing foods each day. (See the Veganism Wikipedia resource list)
I have not personally chosen to move away from my omnivore diet, but I am quite convinced that the vegan diet is the best in terms of preventing cancer development and progression (not to mention its’ well-established benefits in reducing cardiovascular disease and diabetes.)
The Soy Controversy:
Soybeans (and all soy-containing products) are called phytoestogens, because they are able to weakly bind and stimulate estrogen receptors on the surface of certain cells (i.e. breast, ovary.) The active estrogenic compounds in soy are called, isoflavones (i.e. genistein and daidzein.) The concern has been that any stimulation of estrogen receptors may cause the growth of these cells; this is of particular concern if a tumor cell has estrogen receptors (i.e. breast, ovary, endometrial.)
Breast Cancer and Soy:
Recent research suggests that individuals who consume diets that are high in soy, such as those in certain Asian diets (i.e. Japanese) actually have significantly lower risk of breast cancer recurrence than in those who eat low-soy containing diets. Scientists have shown that soy contains estrogen-like molecules (“phytoestrogens”) are able to bind to estrogen receptors, thereby blocking the body’s own estrogen from stimulating the receptor. The soy estrogen only weakly stimulates the receptor, whereas the body’s estrogen (and synthetic estrogen, from medications) strongly stimulates these receptors. The net effect is that soy estrogens can significantly reduce the overall level of estrogen receptor stimulation, leading to diminished tumor growth.
- A study (published in October 2010, in Canadian Medical Association Journal) reports that postmenopausal women with a prior history of estrogen receptor positive breast cancer had a significantly lower risk (33% less!!) of breast cancer recurrence when they consumed higher quantities of soy foods compared to those women who ate smaller quantities. Estrogen receptor positivity or sensitivity means that the breast cancer is stimulated by estrogen. The authors also reported that he risk of breast cancer recurrence was further reduced in the highest soy consumption patients who were also taking a commonly prescribed hormonal anti-cancer medication (Anastrazole.)
- In a study (published in December 2009, in the Journal of the American Medical Association) which examined women with a prior history of breast, the authors reported that soy food consumption (in an amount typically found in an Asian diet) was significantly associated with a decreased risk of death and breast cancer recurrence. Importantly, these results did not vary based on the estrogen-receptor status of the tumor. This implies, that soy may be preventing breast cancer growth through an estrogen-independent mechanism.
If it were only so simple…
- It seems (based on a preclinical study) that soy consumption, when started as an adult, may decrease the effectiveness of Tamoxifen on breast cancer. If soy consumption begins in youth and continued into adulthood during and after a breast cancer diagnosis, soy significantly increases the effectiveness of Tamoxifen on breast cancer.
Prostate Cancer and Soy:
It is believed that the potential protective effects of soy on prostate cancer development and progression are mediated by the phytoestrogen compounds (flavones and isoflavones), which balance against the effects of testosterone and other similar androgens (male hormones.) By reducing the influence of testosterone, phytoestrogens may slow the growth of prostate cancer cells.
- It seems that based on accumulating evidence, consumption of soy foods is associated with a 25-30% reduced risk of developing prostate cancer.
- A small study of men with rising PSA’s after prostate cancer treatment were given a soy product (soy milk). The authors found a 50% response rate in PSA stabilization, at a median duration of 24 months.
Soy and IGF-1:
A small study of healthy postmenopausal women were randomized to receive 3 months of either soy protein concentrate (40 grams protein/day) or a milk protein concentrate (40 grams protein/day). At the end of 3 months, their IGF-1 levels were compared. The authors discovered that the women taking the soy protein had a significantly higher serum IGF-1 level (10.9 nmol/L) compared to the women on the milk protein (4.3 nmol/L). No follow-up studies have been conducted to confirm these findings nor to explore any potential association between soy protein, IGF-1 stimulation and cancer development/progression.
What Soy Foods Are Recommended?:
In Asia, soy is most often consumed in its’ minimally processed (grinding, fermenting, precipitating, boiling) and unaltered state. These foods include:
- boiled soybeans (edamame), tofu (soybean curd), natto (fermented soybeans), miso (fermented soybean paste), okara (a by-product of tofu), soybean sprouts, soymilk, yuba (by-product of soy milk), kinako (soy flour), soy sauce
If you are going to consume soy, the safest approach is to stick with these minimally-processed, soy foods. Although an area of controversy, some studies suggest an increased risk of cancer development and progression associated with the consumption of the processed, extracted isolated soy proteins. These soy isolate extracts may in fact lead to an increased stimulation of estrogen receptors, and should therefore be avoided in patients with estrogen responsive tumors (“estrogen receptor positive.”) Soy milk is often sweetened with sugar. If you are going to consume soy milk, I recommend the unsweetened versions (you can always add Stevia or other low glycemic index sweetener, if you want.)
How much protein do we need?
No one knows, as this is an emerging area of research, but it is certainly going to vary based on an individuals’ daily physiologic requirements. The Institute of Medicine recommends that healthy adults get a minimum of 0.8 grams of protein for every kilogram of body weight (or, 0.36 grams of protein per pound of body weight) per day (i.e. 58 grams for a 160 pound adult.) It is almost impossible if you are consuming enough calories (excluding cancer cachexia, severe illness/infections, starvation and other catabolic conditions) to not consume enough protein to meet our bodily requirements. In the U.S., adults get an average of 15% of their calories from protein, which, in most circumstances, exceeds their minimum daily protein requirements (i.e. for a person who requires a 2,000-calorie-per-day-diet, that’s about 75 grams of protein.)
Cancer patients who are suffering from cachexia (a catabolic/wasting syndrome), will need to increase their intake of protein, fat, and carbohydrates to prevent their body from breaking down its’ own tissues (muscle and fat) to support a much higher metabolic demand. In these circumstances, a nutritionist or dietician who is experienced in working with cancer patients should be consulted to help.
Mercury Contamination In Fish and Shellfish:
Unfortunately, there are many species of fish and shellfish that contain high-levels (i.e. greater than 0.2 parts-per-million) of mercury, a toxic, heavy metal pollutant that comes from industrial waste.
Whenever possible, select fish and shellfish that contain the lowest mercury content (i.e. canned light tuna, salmon, pollock, cod, shrimp, scallops, clams, flounder or sole) and limit your consumption of heavily contaminated species (i.e. swordfish, shark, fresh or frozen tuna, orange roughy, red snapper, grouper, lobster)
See the U.S. Environmental Protection Agency link for more information
Resources:
Harvard School of Public Health: Protein Information
American Institute for Cancer Research: Diet Information
Dr Dean Ornish: The Spectrum Diet
Zest for Life: The Mediterranean Anti-Cancer Diet: Conner Middelmann-Whitney
Foods to Fight Cancer: Essential foods to help prevent cancer: Richard Beliveau, PhD
Life Over Cancer: The Block Center Program for Integrative Cancer Treatment: Keith Block, MD
Anticancer, A New Way of Life: David Servan-Schreiber, MD PhD
Veganism: Wikipedia (excellent reference list on the bottom of the page)
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