Because I like Ben Goldacre's book a lot I will quote a few of the more relevant passages. First one will be from the chapter on nutritionists. "Diet has been studied very extensively, and there are some things that we know with a fair degree of certainty: there is reasonably convincing evidence that having a diet rich in fresh fruit and vegetables, with natural sources of dietary fiber, avoiding obesity, moderating one's intake of alcohol, cutting out cigarettes, and taking physical exercise are protective against such things as cancer and heart disease. Nutritionists don't stop there, because they can't; they have to manufacture complication, to justify the existence of their profession. These new nutritionists have a major commercial problem with the evidence. There's nothing very professional or proprietary about "Eat your greens," so they have had to push things further. But unfortunately for them, the technical, confusing, overcomplicated,tinkering intervention that they promote-the enzymes, the exotic berries-are very frequently not supported by convincing evidence."
Peace Skeptical DoDo