Diet is a four-letter word, which is apropos, since the food you eat can carry health consequences that are profane.
Take high-protein diets. Promoters of such a dietstyle tout the weight loss and strength building effects of eating like our ancestors did for millennia. Weight loss. Muscle mass. Strength gains. These are all short term results. What about long term consequences of favoring animal products? These cavemen ancestors of ours had life expectancies which barely reached the thirties. (This held true in later eras, even through the early part of the 20th century.) It's not to say that eating meat led to an early death; skeletal remains suggest that our ancestors died as a result of trauma, infection, or other such causes, and recent increases in life expectancy are largely due to advances in public health (cleaner water, vaccines, etc).
Nevertheless, most cavemen did not live very long, so it becomes difficult to assess the impact of a meatcentric diet in an older population. Had our ancestors lived to a ripe old age as do we modern humans - the current life expectancy is 78 years and growing, and a much larger portion of the population reaches old age than ever before in history - and had our ancestors persisted in a diet emphasizing meat, what would have been the consequences? Can we say? Yes, we can.
Many modern Americans eat in such a way, breakfasting on eggs, chowing on chicken breast for lunch, and slicing into a steak or roast or chunk of salmon for dinner. And what is the effect?
Cancer is a disease of old age - most cases occur in your 50s or 60s - and cancer is on the rise. A person's lifetime risk of cancer is nearly 50%. This means that 1 in 2 men and women will be diagnosed with cancer during their lifetime. Think of how many people you know who have been diagnosed with the disease. Staggering.
Not coincidentally, per capita animal protein is also higher than it has been historically. In the last century, consumption of meat has risen dramatically, from 10 billion pounds in 1909 to over 50 billion pounds in 2012. That's a 500% increase! Yes, per capita meat consumption has begun to drop in the last few years, but still the average person consumes around 270 pounds of meat per year.
Not coincidentally, if you look at cancer mortality over the same period of time (20th century into the 21st century), we find that cancer mortality rates skyrocketed throughout the last century, reached a peak in the 1990's, and though they have been declining slightly since then, at 190 deaths per 100,000 members of the population per year are still over three times what they were in the year 1900.
Death Rates by Cause of Death, 1900–2005
(per 100,000 population)
Cancer incidence figures are hard to come by, and organizations like to manipulate cancer stats to make them appear less dire than they are, but the fact that meat eating and cancer risk are related goes without saying. Dietary factors are responsible for a large portion of cancers seen particularly in the Western Hemisphere. The World Health Organization associates diet with carcinomas of the pharynx, larynx, lung, esophagus, stomach, colon and cervix. And a study featured in the journal Medical Hypotheses supports a low-fat vegan diet to be especially protective in regard to cancers of the breast and prostate. Interestingly, the same author has shown in another study that low-fat vegan foods, through the same mechanism (lowering circulating levels of certain growth factors seen in cancer) may slow the aging process.
But this is only an aside.
Granted, other changes have taken place in the last 100 years that may influence cancer's rise. These include a consumption of processed and fast foods, Omega-6 saturated diets, exposure to thousands of chemical pollutants never before seen in the history of mankind, entrance of known carcinogens such as chlorine and fluoride in the public water supply, and the explosion of cigarette smoking in society after WWII.
But if it were true that these factors and not an increase in animal protein consumption were the true contributors/causes of cancer, we would expect to see the same rates of cancer in meat-eaters and vegetarians/vegans alike.
But we don't.
Many and various are the studies which have shown that vegetarian diets, and to a greater extent vegan diets, confer a protection against cancer, none more so than a recent and very elegant study conducted at Loma Linda University, which showed that vegan women had 34 percent lower rates of cancers of the breast, cervix, and ovary compared to a group of healthy omnivores who ate substantially less meat than the general population. The risk of dying from a heart attack is also less in plant eaters, notable since heart disease tops cancer as the nation's biggest killer.
Recent literature has touted the success of the war on cancer, but it is a success of cancer treatment, not prevention. Drugs and invasive surgery, though effective on existing malignant neoplasms, are powerless in preventing a tumor's occurrence. For many, the battle is lost once cancer rears its ugly head. Does it have to be you or a loved one? No it doesn't. Of what good is reaching your target weight by eating certain foods if in 10, 20, or 30 years those very foods bring with them sickness and death and cut your life in half?
There are other ways of eating which carry with them the benefit of weight loss and improved fitness without the attendant risk of cancer. So eat more plants. The overall quality of your diet can be gauged by the proportion, by calories, of fruits, vegetables, beans and seeds you consume.
Think long term. Lifespans being longer than they have ever been before, it is now more important than ever to maintain optimal health well into old age, since you may reach the century mark or beyond, and we hope you do so in vibrant health, vim, and vigor.