Raw foods: upside and downside

Philip J. Goscienski, M.D.

June 2007

For a couple of million years cooked plants and animals were accidental and fleeting additions to the Stone Age menu. Our intestinal tracts evolved to handle raw foods well. We didn't start cooking on purpose until about 150,000 years ago. Does that mean that cooked food is unnatural and that we should avoid it? For thousands of generations we didn't bathe, immunize our children or take antibiotics, either. Should we avoid these practices as well?

If you never cook vegetables your health won't suffer. That doesn't work too well for grains such as wheat because they need to be heated and crushed in order to make them available to humans' digestive processes. Some raw foods such as oysters, sushi and steak tartare have attained gastronomic elegance.

Raw food advocates have a valid point: heat destroys some nutrients. On the other hand, heating food helps the digestive process by bursting the rigid cell walls of plant foods. This actually makes the nutrients inside more available. Cooking also makes meat easier to digest. In almost all societies on the planet, cooked foods have a place in the local cuisine.

Do you have a family history of kidney stones? Some persons have a tendency to form kidney stones from oxalate that is present in fairly large amounts in raw leafy vegetables such as spinach and Swiss chard. You can remove from 30 to 87 percent of the oxalate from these vegetables by boiling them but susceptible individuals ought to limit their intake even of cooked versions.

Several types of microorganisms, including viruses, bacteria and parasites have been sickening and sometimes killing humans for as long as we've been on the planet together. Some of these germs or the poisons that they generate might get through the cooking process but the risk is certainly higher in uncooked food. It's true that there is some antibacterial activity in raw vegetables but it's too modest to overcome frank contamination.

The proponents of raw food claim that cooking destroys enzymes that we need for optimal health but that has been hard to document. Enzymes are proteins and we digest them just like any other protein. They are also relatively large molecules and a healthy intestinal tract will simply not absorb them.

Many raw food enthusiasts are vegans and eat no animal products. Back in the Stone Age that didn't lead to nutritional deficiencies. The food that they ate was contaminated with dirt that supplied essential minerals and insects that provided vitamin B12. Who would want that now? Vegans who do not plan meals carefully and do not supplement are at risk of becoming deficient in iron, iodine and vitamin B12.

When raw food advocates argue that cooked foods cause cancer they have a valid point. High cooking temperatures that produce charring lead to the formation of heterocyclic amines from amino acids, creatinine and glucose that are indeed associated with a higher risk of cancer of the colon.

Enjoy raw foods but don't overlook the need to clean them well before you eat them. And yes, commercial vegetable washes do help to remove germs that could make you ill.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.