Protein is a vital macronutrient that supplies the building blocks for bones, skin, organs and muscles as well as key immune-system components such as white blood cells. We all need to eat protein daily, but it’s especially important for people with chronic diseases to consume high-quality protein to maintain muscle mass and support the immune system.
Moreover, protein-rich meals can help prevent weight gain by keeping us sated longer than meals consisting mainly of carbohydrates. Some protein and a little healthy fat should therefore be included in every meal; this increases satiety and helps prevent blood-sugar swings and starch/sugar cravings. (For example, a salmon-and-vegetable curry with a little brown rice is likely to be more satisfying than a vegetable-only curry with rice).
Foods that supply high-quality protein include eggs, fish, legumes (beans, peas, lentils, soy, nuts and nut butters), deep, cold-water fish (salmon, sardines, mackerel, cod), poultry (skin removed), whey (a milk protein), whole grains, nuts and seeds.
You don’t have to completely eliminate dairy and meat from your diet to live an anti-cancer lifestyle, but you should limit the quantity you consume, choose the highest-quality meats you can afford, prepare these carefully to avoid creating carcinogens (more on this below) and accompany them with a wide variety of colorful vegetables and fruits.
Dairy and Cancer:
- 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 also 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 in this blog post)
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) (Learn more about sugar, insulin, IGF-1 and cancer in this blog post)
- 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 to stimulate cancer growth in humans, as discussed in Dr. T. Colin Campbell’s 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. (On the other hand, calcium may be protective against colon and bladder cancers.)
- Many people do not tolerate lactose, the sugar in milk that causes diarrhea and cramping in some people. In the U.S. alone, lactose intolerance is thought to affect over 30 million adults.
- Humans are the only mammals who drink milk after infancy and who drink the milk of another species. After infancy, milk is not essential to human health; after all, most adult Africans and Asians do not consume dairy because they lack the enzymes to digest it properly, and they are nonetheless healthy.
If you do wish to consume dairy products occasionally, we recommend:
- Organic dairy products that were produced without the use of hormones; they should beclearly labeled “No rBGH” to minimize your exposure to excess levels of IGF-1
- Lower-fat dairy products (e.g. fresh curd cheese instead of aged full-fat cheese, or frozen yogurt instead of full-fat ice cream)
- Dairy foods from grass-fed animals (producing higher amounts of omega-3 fatty acids in their milk and meat)
- Fermented curds and cheeses made from goats’, ewes’ and occasionally cows’ milk (e.g. kefir, yogurt, halloumi and feta cheese). These are the dairy products that are (sparingly) included in the traditional Mediterranean diet
Meat and Cancer:
- 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 here.)
- 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 here; they tell us it’s all quite safe)
- Observation studies have linked diets high in red meat with an increased risk of developing cancers (colorectal, lung, breast, uterine, ovary, prostate) and cancer recurrence.
- These studies are not conclusive as they may be confounded by the possibility of associated poor lifestyle risk factors that are known to be risk factors for cancer (i.e. smoking, sedentary lifestyle, alcohol consumption, obesity, lower consumption of fruits, vegetables and whole grains.)
- Other limitations of these studies are that they did not assess the type of meat consumed in terms of organic vs. non-organic, grass-fed vs. grain-fed, antibiotic & hormone-dosed.
- The bottom line: “If you do eat red meat, less is better than more, and grass-fed, grass-finished beef offers a far better omega-3 to omega-6 fatty acid profile, along with fewer contaminants and less fat.” –Dr. Andrew Weil
- Processed meats (bacon, hot dogs, deli meats), likely through carcinogenic nitrites, are linked to the development of numerous cancers. (Read more about cured meats and nitrites here.) Avoid these wherever possible.
- Many meat products are high in saturated fat which is associated with increased systemic inflammation, increased production of cancer-causing free radicals and weight gain. (Read more about fats and cancer here.)
When you consume meat products, we recommend:
- Organically raised (look for ‘hormone free’ labels) meat from grass-fed animals, which is thought to contains a healthier fatty-acid balance and more antioxidant nutrients). A 2009 USDA study found that grass-fed beef was lower in total and saturated fat and higher in omega-3’s, higher in the antioxidants beta-carotene and vitamin E (alpha-tocopherol), higher in the B-vitamins thiamin and riboflavin, higher in the minerals calcium, magnesium, and potassium and had a healthier omega-6-to-3 ratio than grain-fed beef.
Moreover, a recent study showed that red meat from grass-fed animals raised blood levels of omega-3 fatty acids in people who ate them.
- Fresh, unprocessed meat
- 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 and choose moderate portion sizes,. The American Institute for Cancer Research/World Cancer Research Fund recommends eating no more than 18oz/500g of cooked red meat a week. (This is roughly equivalent to 24oz/700g of uncooked meat).
- Prepare meats carefully: cooking them at high temperatures (e.g. pan-frying, flame-grilling, barbecuing etc.) can lead to the formation of carcinogenic compounds. These can be reduced by gentle cooking methods (slow-cooking, poaching, stewing at moderate heat). When you do fry meat, marinate it first in lemon juice or vinegar, herbs and spices; this significantly reduces the amount of cancer-causing compounds that are created during high-temperature cooking.
Eggs and Cancer:
Although the mechanisms to explain this correlation have not been identified, some studies have found an association between egg consumption and cancer risk (particularly, colorectal, bladder and prostate cancers).
We are not convinced of a direct link between egg consumption and an increased risk of cancer. This potential risk may have more to do with other potential confounding factors such as egg quality and preparation methods:
Eggs offer high-quality protein and nutrients at moderate cost and are an excellent protein source for vegetarians. As will all healthy foods, eggs shouldn’t be eaten in excess, but around one egg a day seems acceptable.
To find a source of eggs from chickens raised on pasture, you can visit LocalHarvest.org and do a search for “eggs pastured” or “eggs grass fed” with your zip code. You can also visit EatWild.com and click on your state for a list of farms that pasture their animals.
Can Vegans Get Enough Protein and All The Required Essential Amino Acids?
“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. legumes, fruits, vegetables, grains, nuts) which means they 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)
Indeed, a recent scientific article suggested that due to reduced bioavailability of plant protein, vegetarians who don’t eat much animal protein may need to increase their intake of protein to make up for the deficiency. (This probably applies even more strongly to vegans, who do not eat any animal protein.)
Vegans also need to be careful to eat a diet that is rich in low-GI plant foods (e.g. vegetables, legumes, nuts, seeds, whole grains, minimally processed soy foods, fruits) and avoid eating refined grains, highly processed vegan meat-substitutes and high-GI foods such as grains and baked goods (pizza, pasta, rice, bread, cookies and cakes).
Dr. Lawenda’s favorite vegan protein powder is called Maximum Vibrance. The manufacturer calls this a “superfood” because it not only contains all the amino acids you need to be a complete protein source, but it also has billions of units of probiotics and is loaded vitamins, minerals and phytonutrients…and it tastes good too. Two scoops contains 7 servings of fruits and vegetables, so you are getting lots of good stuff when you drink this. I mix mine into a glass of unsweetened vanilla almond milk.
The Soy Controversy:
Soybeans (and all soy-containing products) contain compounds called 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) 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 the 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.)
**Caveat: The women in this study were Chinese and had presumably been consuming soy all their lives; thus it is possible that these results may not apply to western populations with minimal soy consumption throughout life (i.e. starting in childhood or adolescence).
In a study (published in December 2009, in the Journal of the American Medical Association) which examined women with a prior history of breast cancer, 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.
**Caveat (see caveat note above)
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.
Nonetheless, the picture remains unclear. For instance, in this small study, 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.
Adding further complexity to the soy discussion, how our bodies metabolize the phytoestrogens in soy depends to a large degree on the bacterial balance in our intestines. See this article (http://www.ncbi.nlm.nih.gov/pubmed/15734719) and this one (http://www.ncbi.nlm.nih.gov/pubmed/17579894). Thus, to derive the full benefit of soy foods, it is likely that we need to have healthy gut flora.
To be on the safe side, we recommend that individuals seeking to increase their anti-cancer protection consume whole soy foods rather than isolated soy extracts. (See below.)
Incidentally, many other foods contain phytoestrogens, not just soy. For instance, lignans, which also have antioxidant properties, are converted by our gut bacteria into estrogenlike molecules. Flax seeds are a rich source of lignans, but they are also found in lower concentrations in sesame seeds, whole rye, wheat, oats and barley, legumes and many fruits, berries and vegetables.
One human intervention study indicated that flax seeds may protect against prostate cancer: men with prostate cancer who ate 30 grams (three tablespoons) of ground flaxseed each day for one month had decreased cancer cell proliferation compared to similar men who did not eat flaxseed. Eating a low-fat diet whilst taking the flax seeds (as advocated by Dr. Ornish) conferred no added advantage in this study.
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 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, we 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:
Fish is an excellent source of high-quality protein. Unfortunately, however, 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 with 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).
Download this handy “Healthy Fish Guide” to learn which are the least toxic fish to buy and how much is safe to eat per week.
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
Anticancer, A New Way of Life: David Servan-Schreiber, MD PhD
Veganism: Wikipedia (excellent reference list on the bottom of the page)