The calls to cut back on meat are coming from many directions. The meat industry is a major contributor to greenhouse gasses, climate change, and environmental degradation. Billions of animals suffer and die to satisfy our eating choices.
These altruistic reasons to cut down on meat come on top of the self-serving rationale to do so: Eating less meat is good for you.
Studying the outcomes of a lifetime of dietary habits is difficult – the range of what and how much a person eats is extensive and diets change over time – but decades of research show that the risk of cardiovascular disease is overall lower among vegetarians and vegans. Vegetarians and vegans tend to be thinner, have lower total LDL cholesterol, and lower blood pressures.
A link between meat and cancer is also well studied. The American Cancer Society recommends limiting or avoiding red and processed meats in order to lower the risk of cancers. The World Cancer Research Fund states that if you eat red meat, shoot for no more than 3 portions (12-18 oz cooked weight) a week, and consume very little if any processed meat.
Low meat, fish, and vegetarian diets and cancer risk
As noted from the above recommendations, it’s not just vegetarians that can lower their disease hazard, as the risk from meat is cumulative and dose dependent.
A new study in BMC Medicine analyzed the nutrition data from almost half a million British adults, aged 40-70 years, and looked at the incidence of cancer over 11 years, also controlling for diabetes, socioeconomic factors, smoking and obesity.
About half (52 percent) of the cohort ate meat more than 5 times a week, 44 percent ate meat less than 5 times a week, 2 percent ate only fish but no meat, and 2 percent were vegetarian or vegan.
The study finds that those who ate meat less than 5 times a week had a 2 percent reduction in cancer incidence, fish eaters had a 10 percent reduction, and vegetarians and vegans had a 14 percent reduced risk. Low meat, fish and vegetarian eaters had lower risks of all-cause cancer, and especially colorectal, prostate and breast cancer.
But although the study controlled for confounders such as weight status and exercise, the authors note that: “Vegetarians and fish-eaters differ from meat-eaters in many non-dietary lifestyle factors such as lower smoking and alcohol consumption, and higher physical activity. Although relevant potential confounders were added to the multivariable models to adjust for these differences, imperfect measurements and/or changes in these confounders over time may result in incomplete adjustment for these variables.”
Not all meat-free diets are created equal
Not all foods of plant origin are healthy though: French fries, chips and soda are utterly vegan, and obviously don't promote health.
Meat avoidance, in and of itself, doesn’t tell us enough about what people actually eat, therefore studies that look at the content of plant-based diets are informative.
The longest living group of Americans are probably The Seventh Day Adventists, whose health habits—promoted by their religion—include vegetarianism, as well as avoiding alcohol and smoking. Adventists as a group aspire to these rules, and are generally health conscious, but individual adherence is variable, and not all adventists avoid meat. Studying and subgrouping this diverse cohort is revealing.
A new study in the American Journal of Clinical Nutrition following about 77,000 members of the Adventist church for about 7.5 years looked at their rates of death from any cause, and correlated it with how much ultra-processed foods and meat they ate.
And the results: Eating more ultra processed foods was associated with a 14 percent higher incidence of death. Eating more red meat was also linked with an 8 percent increase in all cause mortality.
The quality of any diet is determined by what you eat more of, and also what you eat less of.
Instead of categorizing a food just as plant-based you should also question its nutritional quality.
A recent study in the American Journal of Clinical Nutrition including almost 130,000 people, followed for 20 years, sought to see if plant-based diets affect weight gain, which is an important risk factor for many chronic diseases.
The study uses three indexes of plant-based diets. The first is an overall plant-based index, in which plant-based foods receive a positive score, and animal foods receive a negative one. The other two are subcategories of the first one and rate the healthfulness of of the plant based components of the diet, adding points for healthful plant based foods (whole grains, fruits, vegetables, nuts, legumes, vegetable oils, tea/coffee) and reducing score for less healthy plant foods (sweetened beverages, refined grains, sweets/desserts).
Participants gained on average 2 to 4.5 pounds every 4 years. Diets that were more plant-based mitigated weight gain. But not all plant-foods and meat avoidance regimens fared equally: People who ate a more healthy plant based diet gained 1.5 pounds less. People who ate an unhealthy plant-based diet gained about 1 pound more.
Similar results are seen studying type 2 diabetes: Overall a high plant-based diet and especially healthy plant-based diets are linked with lower the risk of diabetes. Unhealthy plant-based diets, however, are actually associated with higher rates of type 2 diabetes.
And the same goes for cardiovascular disease: although sticking to a more plant-based diet seems to be protective, when examined more carefully the subgroups of plant-based eating patterns diverge – healthier plant-based diets are linked with lower heart disease risk, but an unhealthy plant-based diet confers a higher risk.
Watch out for highly processed food
As plant based meat and milk alternatives expand – clearly a blessing for animal rights and environmental benefits – make sure that you’re not replacing an eat-less-of ingredient with yet another one that we should watch for: highly processed food.
Many in the meat avoiding population are health conscious, and their wellbeing can be attributed to the myriad of healthy routines they practice, in diet, physical activity, mental wellbeing, smoking avoidance etc., all working in conjunction.
Vegetables and plants are the essence of a healthy vegetarian lifestyle, meat avoidance alone doesn’t do the trick – and meatless burgers are hardly a plant.
Dr. Ayala