Scientists from the University of Washington evaluated the health risks of smoking, eating red meat, and eating a vegetable-heavy diet. Research published nature medicine.
Scientists evaluated the quality of the scientific evidence for the harms of various habits. Each habit was rated from one to five stars, with five stars representing the highest quality of evidence linking the habit with disease.
Four to five stars were assigned to smoking when considering cancers of the pharynx, larynx, trachea, bronchi, and lung, as well as chronic obstructive pulmonary disease, aortic aneurysm, peripheral artery disease of the lower extremities, and pancreatic cancer.
Scientists have found evidence that red meat consumption leads to colon, breast and rectal cancer. But the evidence only got two stars. The authors of the analysis suggested that the conflicting data may be due to the fact that fat and cholesterol in themselves are not so dangerous, but problems arise when they are consumed with excess carbohydrates. This issue requires more research, but for now, excess red meat will continue to be a risk factor for many diseases.
Five-star evidence shows that diets low in vegetables do not necessarily lead to serious illness. The most serious consequence of the low-veg diet was ischemic stroke, which was rated three stars. Two stars received coronary heart disease, stroke, and esophageal cancer. Scientists believe that what matters more is the overall nutritional quality, not the fact of eating vegetables. The authors’ conclusions do not mean that vegetables are of no use, they simply show that they cannot compensate for other aspects of malnutrition.