kat : Here's something I want to get off my chest. Evidence is growing that diet and environment may be key culprits in causing breast cancer, according to a recent report on PRI's Living On Earth. A professor of epidemiology, Dr. Devra Lee Davis, emphasized the importance of "eating low on the food chain." What constitutes a low-on-the-food chain diet?
Dr. Nestle: This is an old idea that received wide attention when Frances Moore Lappé changed the way everyone thought about food in her book, Diet for a Small Planet in 1971. Food chains refer to who eats what. We are at the top of the food chain. We eat animals; animals eat plants or smaller animals; smaller animals eat plants and even smaller animals. The smallest animals eat only plants. This puts plants at the bottom of the food chain. Eating low on the food chain means eating mostly plants. This is better from the standpoint of food resources (it takes several pounds of plants to create a pound of meat) and of health (less saturated fat).
kat: Dr. Davis also noted that low-on-the-food-chain foods "are low in pesticides -- the fatter the food, the more opportunities it has to absorb toxic chemicals, so eating a diet that is low in animal fat is important." Why do fatty foods absorb more toxins, if this is not too technical a question to ask?
Dr. Nestle: Of course not. Most toxins are organic compounds that are soluble in fat, not water.
kat: But are all animal fats created equal? Is all red meat bad, or do grass-fed meats have health benefits, as Jo Robinson's Why Grassfed is Best claims?
Dr. Nestle: The fat issue is really about ruminants -- beef cattle -- and you have to be able to handle some fat chemistry to understand what it is about. As I explain in What to Eat (see pages 176-179 on "Animals: Grass Fed and Grass Finished"), bacteria in the cow's rumen add hydrogen to the otherwise unsaturated fatty acids in grass. This makes beef fat more saturated, which is not so good for heart disease risk. But some of the unsaturated fatty acids get hydrogenated in a different way and form "conjugated linoleic acids" (CLAs). These are trans fats, but somewhat different from the trans fats that get formed by artificial hydrogenation (I describe the structural differences in the endnote to page 177).
kat: Robinson also maintains that the CLAs in full fat grass-fed dairy actually lower cholesterol. True?
Dr. Nestle: The research on CLAs is preliminary but suggests that grass-fed beef is healthier than beef fed corn and soybeans. I am not convinced that the evidence is all that strong but others would surely disagree.
kat: OK, so the jury's out on whether grass-fed meat and dairy can reduce your cholesterol levels, but steering clear of factory farmed meats full of hormones, antibiotics, pesticides and chemicals may decrease your risk of cancer, and eating humanely raised (i.e. grass-fed) meats is bound to boost your karma!
Dr. Nestle: I couldn't agree more.
This post first appeared on Eating Liberally.