Simon Weiss was my father-in-law. He was a butcher and had a saying “the meat makes the meal.” Of course, he would eat meat more than once a day. He died of a stroke at age 92 several years ago, but lived a relatively disease-free life. As I grew up and even in medical school we were taught meat and dairy were great sources of protein, but plants were not. In my medical practice, patients frequently ask me what I think of a vegan or vegetarian diet. Up until 2005, when a book called The China Study was published, physicians didn’t have a lot of scientific data to go by. The China study is a 20 year observational study involving 6,500 individuals living in 130 villages in China. Colin Campbell, PhD and Thomas Campbell, M.D., his son, are the authors. Dr. Campbell is a Professor Emeritus of Nutritional Biochemistry at Cornell University. The study concluded that people with a high consumption of animal-based foods (meat, eggs, dairy products) were more likely to suffer chronic disease (such as diabetes, heart disease, cancer), while those who ate a plant-based diet were the least likely. A closer look at the study reveals important limitations that impact the reliability, usefulness, and interpretation of the study results. There are technical issues with the limited number of data points. And the study jumps to conclusions and doesn’t differentiate between causation and association.
Key et. Al in 1998 did an analysis of 5 large prospective studies and found no difference in death rates from certain cancers (stomach, colon, lung, breast, and prostate) among vegetarian vs. non-vegetarian. Key found that vegetarians were less likely to die of ischemic heart disease than non-vegetarians.
Factors Other Than Just “Too Much Animal Protein.”
Less than sixty years ago, cows and poultry were different than they are today. Back then, animals were allowed to roam freely outdoors. Cattle grazed off grass or hay and were not given estrogens and androgens, antibiotics, genetically modified corn or soy, or growth hormones. Chickens were also allowed to roam freely and not confined many to a cage. They also were not given hormones or antibiotics, and were not fed grains that had been adulterated with arsenic to kill parasites (after decades of arsenic use in the U.S. poultry industry, the FDA this year, after mounting pressure, banned this practice because of the harm it could cause in humans). The meat from grass-fed cattle have a higher Omega-3 oil content than seafood, and the human body will do well with some meat if it is organic, free range and not eaten more than once a week. Be warned that a product labeled “natural” is not the same thing as “organic.” And that “natural” product may contain hormones or antibiotics. Personally, I get most of my protein from wild Alaskan salmon or cod (not farm raised), which is very low in mercury and other contaminants.
There are some forms of meat that are especially harmful. Preserved meats (ham, cold-cut turkey or beef, bacon, hotdogs, salami, pastrami or other deli meats) contain added nitrates, which have been linked to a variety of cancers. They also contain sodium, which patients with heart or kidney disease, or hypertension may need to avoid. Barbequed meats (and vegetables) are highly toxic. I used to BBQ a lot and didn’t really want to believe this because I loved picnics and family events. But I did some research. What happens is that fire or hot metal directly touches the food without the presence of liquid or oil, and will burn the food, creating cancer-causing free radicals called polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs). They are formed whenever there is incomplete combusion or burning. This incomplete burning also occurs in cigarettes. Polycyclic aromatic hydrocarbons are the main cancer causers in cigarettes. But such incomplete burning also takes place in charcoal grills and in the smoking of food. The fat drops on the charcoal, partially burns and spatters up onto the meat. Charcoal grilled meat contains large quantities of such chemicals. A 1.1 kilogram (2.4 pound) charcoal grilled steak contains as much cancer causing chemicals as 600 cigarettes according to a 1964 article in Science magazine! These chemicals last in the body up to a month, which is a long exposure. Worst of all is that they taste good, so you don¹t realize what you are taking in. The position of the National Cancer Institute is that although there are studies linking PAHs and HCAs to multiple different types of cancer in animals (including breast, colon, prostate, leukemia, skin, and liver) there are no direct studies that show barbequing food causes cancer in humans. But then the National Cancer Institute “hedges” on their website and goes on to say “Nevertheless, numerous epidemiologic studies have used detailed questionnaires to examine participants’ meat consumption and meat cooking methods to estimate HCA and PAH exposures. Researchers found that high consumption of well-done, fried, or barbecued meats was associated with increased risks of colorectal, pancreatic, and prostate cancer.”
The National Cancer Institute recommends if you must BBQ, before you barbecue meat, partially cook it in the microwave and then throw out the juices that collect in the cooking dish. Finish cooking the meat on the grill. Precooking a hamburger for a few minutes in the microwave reduces polycyclic aromatic hydrocarbons by up to 95 percent, and frequently flipping burgers further reduces PAHs. The longer the cooking time and the higher the heat, the more HCAs. Barbecuing produces the most HCAs, followed by pan-frying and broiling. Baking, poaching, stir-frying, steaming and stewing produce the least HCAs. The National Cancer Institute suggests keeping the cooking temperature at 300 degrees or below to avoid HCA production.
I leave the choice of whether to eat meat in limited quantities or not up to each patient. I do encourage cancer patients and those with chronic diseases to emphasize a plant-based diet and minimize meat and dairy.