Yes it can . Good nutrition can also prevent the diseases ( plus many others ) in the first place. These conditions are brought on by poor diet. For example, the incidence of colo-rectal cancers is high in North America but low in Asia. It has been proven that the western dietary emphasis on meat products is the culprit in this case. Asians traditionally have eaten little red meat. Dubious dietary choices also are factors with heart disease and diabetes. Here again, the instigators are excessive animal product, processed food, and fat consumption So it is not unreasonable to assume that these ailments can also be corrected by diet. But this has to be a good one. Not the usual garbage peddled by the giant agribusiness/chemical industries, but rather an emphasis on whole, mainly vegetarian foods, as close to their original form as possible. Raw is the key word here. Little if any processed food. A higher proportion of alkaline foods over acidic ones. I believe that if the population affected by these ailments even only partially adopted some of these sensible dietary guidelines, then the illnesses in question would no longer have such catastrophic consequences for so many. However, as long as officials, the medical industry and the media continually parrot the "health" benefits of animal foods to the credulous public, plus the unproven treatment approach to illness, then practical nutritional advice will continue to take a backseat to profit margins.