The raw food movement began with a fringe group of eaters in the mid 1970s and has since gained mainstream status along with other alternative diets such as veganism and macrobiotic eating. Most major cities and many smaller ones now boast raw food restaurants. Raw cookbooks abound and celebrities like Carol Alt, Woodie Harrelson and Natalie Portman have gone public with their raw food habits.
A cornerstone of raw foodism dictates that uncooked food is more nutritionally intact and bioavailable to humans. Raw foodists point out that all natural foods have the enzymes necessary to break down their matter, but that these enzymes are destroyed by cooking temperatures. Such followers believe that by eating only foods that contain their own decompositional enzymes, the body does not have to produce its own digestive enzymes (from the pancreas) and can redirect the energy elsewhere. Raw foodists also believe that an uncooked meal is more nutritious than cooked counterparts because of some evidence that cooking leaches nutrients.
But new evidence published in the upcoming issue of the British Journal of Nutrition suggests that vegetables do not always provide optimal nutrition when consumed raw. Instead, several vegetables are more nutritious after cooking or when served with other ingredients, such as fats. In the published study, 198 German citizens followed a 95% raw diet and underwent blood analysis throughout their experiment. While the subjects had average levels of some plant-derived nutrients such as beta-carotene and vitamin A, they had surprisingly low levels of other nutrients, such as licopene – a potent antioxidant that is found in tomatoes.
Licopene from tomatoes, it seems, is more readily available to the body when cooked because the heat breaks down the cellular walls of the tomato, allowing for more licopene to leach out during digestion. Without heat, much of this licopene passes through the body in intact cells. Fats such as olive oil are also useful in digesting licopene because the nutrient is fat-soluble, making the fat an efficient delivery system. These techniques amount to a significant distinction: tomato sauce, for example, has more than five times the amount of lycopene as the equivalent amount of raw tomato.
But tomatoes aren’t the only vegetables that benefit from a bit of heat. The Journal of Agriculture and Food Chemistry published a study (summarized in the New York Times here) found that several vegetables such as carrots and zucchini provided the most nutrition when they were boiled.
While vegetables are obviously healthy in most contexts, its interesting to note that human innovation and techniques are sometimes more beneficial than we give them credit for. Long live caprese salads and their abundance of fat-tastic lycopene delivery mechanisms!