The Cold Truth About Raw Food Diets
By Joel Fuhrman, M.D., www.drfuhrman.com
Contrary To The Propaganda Of Raw-Food Advocates, Cooking Actually Can Help You Absorb More Nutrients.
The raw-food movement continues to make converts, thanks to a devoted group of individuals and celebrities who embrace the belief that an all-raw food diet is the best diet. The idea that stirs the most enthusiasm for this diet is the contention that cooking both destroys about fifty percent of the nutrients in food, and destroys all or most of the lifepromoting enzymes. Raw-food enthusiasts commonly make the claim that “cooked foods are dead foods.”
Are Cooked Foods Really Dead Foods?
It is true that when food is baked at high temperatures— and especially when it is fried or barbecued— toxic compounds are formed and important nutrients are lost. Many vitamins are water-soluble, and a significant percent can be lost with cooking, especially overcooking. Similarly, many plant enzymes function as phytochemical nutrients in our body and can be useful to maximize health. They, too, can be destroyed by overcooking.
Enzymes are proteins that work to speed up or “catalyze” chemical reactions. Every living cell makes enzymes for its own activities. Human cells are no exception. Our glands secrete enzymes into the digestive tract to aid in the digestion of food. However, after they are ingested, the enzymes contained in plants do not function as enhancements or replacements for human digestive enzymes. These molecules exist to serve the plant’s purpose, not ours. The plant enzymes get digested by our own digestive juices along with the rest of the food and are absorbed and utilized as nutrients.
Contrary to what many raw-food web sites claim, the enzymes contained in the plants we eat do not catalyze chemical reactions that occur in humans. The plant enzymes merely are broken down into simpler molecules by our own powerful digestive juices. Even when the food is consumed raw, plant enzymes do not aid in their own digestion inside the human body. It is not true that eating raw food demands less enzyme production by your body, and dietary enzymes inactivated by cooking have an insignificant effect on your health and your body’s enzymes.
Cooking Can Be Beneficial.
In many cases, cooking destroys some of the harmful anti-nutrients that bind minerals in the gut and interfere with the utilization of nutrients. Destruction of these anti-nutrients increases absorption. Steaming vegetables and making vegetable soups breaks down cellulose and alters the plants’ cell structures so that fewer of your own enzymes are needed to digest the food, not more. The point is that this “cooked food is dead food” enzyme argument does not hold water. On the other hand, the roasting of nuts and the baking of cereals does reduce availability and absorbability of protein.
When food is steamed or made into a soup, the temperature is fixed at 100 degrees Celsius or 212 Fahrenheit— the temperature of boiling water. This moisture-based cooking prevents food from browning and forming toxic compounds. Acrylamides, the most generally recognized of the heat-created toxins, are not formed with boiling or steaming. They are formed only with dry cooking.
Most essential nutrients in vegetables are more absorbable after being cooked in a soup, not less absorbable. Recent studies confirm that the body absorbs much more of the beneficial anti-cancer compounds (carotenoids and phytochemicals— especially lutein and lycopene) from cooked vegetables compared with raw. The Institute of Food Research in Norwich reported their recent findings in New Scientist magazine: about 3 to 4 percent of the carotenoids were absorbed from raw carrots compared with about 15 to 20 percent from cooked and mashed carrots. The team also found that we absorb these critical anti-cancer nutrients more effectively from vegetables than we do from supplements.
Multiple studies have demonstrated that the beneficial antioxidant activity of cooked tomatoes is significantly higher than from uncooked tomatoes. Scientists speculate that the increase in absorption of antioxidants after cooking may be attributed to the destruction of the cell matrix (connective bands) to which the valuable compounds are bound.
Loss Of Nutrients
It is true that vitamin C, folate, B vitamins, and certain minerals are water-soluble and can be destroyed by cooking; but vitamin C contributes less than one percent to the total antioxidant activity of fruits and vegetables. For example, the main antioxidant activity in apples is provided by classes of chemicals called phenolics and flavonoids, both of which are made more available by cooking.
If you compare raw broccoli to steamed or frozen broccoli, about 25 percent of the vitamin C and about 20 percent of the selenium is lost during cooking, but the other 20 commonly-measured nutrients show only an insignificant change. Raw-food advocates are not accurate when they claim that 50 percent of nutrients are lost with steaming. A closer estimate would be 10 percent.
Cooking corn also has been shown to significantly boost its antioxidant activity, despite reduction in vitamin C. When the ability to quench free radicals was measured, cooked corn outperformed raw corn by between 25 to 50 percent. Cooking corn releases a compound called ferulic acid, which provides anti-cancer health benefits. Ferulic acid, a phytochemical, is unique in that it is found only in very low amounts in fruits and vegetables, but is found in very high amounts in corn. The availability to the body of ferulic acid can be increased 500 to 900 percent by cooking the corn.
Benefits Of Raw Food
Certainly, there are benefits to consuming plenty of raw fruits and vegetables. These foods supply us with high nutrient levels and the smallest number of calories. But the question we are looking at is this— Are there advantages to eating a diet of all raw foods and excluding all cooked foods?
Clearly, the answer is a resounding “No.” In fact, eating an exclusively raw-food diet is a disadvantage. To exclude all steamed vegetables and vegetable soups from your diet narrows the nutrient diversity of your diet and has a tendency to reduce the percentage of calories from vegetables, in favor of nuts and fruit, which are lower in nutrients per calorie.
Unfortunately, sloppy science prevails in the raw-food movement. Raw food advocates mistakenly conclude that since eating processed and cooked carbohydrates is harmful for us, all cooked foods are harmful.
To eat the most healthful diet on earth, include a sufficient quantity of raw fruits, vegetables, nuts, and seeds. If you are not very overweight or diabetic, add a glass of freshly squeezed raw vegetables to your diet. Try one of the following combinations—beet/carrot/cabbage/apple; kale/parsley/carrot/apple; or beet/carrot/celery/cucumber. Have a blended salad a few times a week.
In addition, try to consume an adequate amount of cooked food, especially vegetable soup.