On the whole, a good 99% of discussion on the topic of the human diet is nonsense - that marketplace of ideas and goods is just as bad as the anti-aging marketplace. If you pick out a group at random, the odds are very good that you'll be pointing to a coven of fools who have found ways to make money from ignorance and hope. There are always potential customers whose desire for immediate solutions and answers overwhelms their desire for actually working solutions and correct answers.
The areas where science has robust things to say about diet, advice proven beyond any reasonable doubt, largely revolve around levels of calorie intake and recommended levels of micronutrients. Calorie restriction, for example, is undeniably good for you. Keeping your micronutrient intake up to scratch is also a good thing. After that, we devolve into studies for, studies against, and debates that can be argued well in either direction. So, given the existance of the diet industry and its idiocies, I tend not to talk too much about diet. This is for much the same reasons that I don't talk much about skin rejuvenation or hair restoration. There are occasional flashes of good science amidst the foolish braying of the sellers, but most of the broader discussion is worthless and a distraction.
Here, for a change, are a couple of recent items on aging and diet: we know that advanced glycation endproducts (AGEs) and insulin signaling are both important to the way in which metabolism determines degeneration and life span, the latter probably more so. But how does diet enter into this? AGEs are generated in the body, but also consumed. Insulin signaling is intimately tied to levels of sugar in the blood, which changes with the level of glucose in the diet.
By adding just a small amount of glucose to C. elegans usual fare of straight bacteria, they found the worms lose about 20 percent of their usual life span. They trace the effect to insulin signals, which can block other life-extending molecular players. Although the findings are in worms, Cynthia Kenyon of the University of California, San Francisco, says there are known to be many similarities between worms and people in the insulin signaling pathways.
Researchers from Mount Sinai School of Medicine report that cutting back on the consumption of processed and fried foods, which are high in toxins called Advanced Glycation End products (AGEs), can reduce inflammation and actually help restore the body's natural defenses regardless of age or health status. These benefits are present even without changing caloric or nutrient intake.
"What is noteworthy about our findings is that reduced AGE consumption proved to be effective in all study participants, including healthy persons and persons who have a chronic condition such as kidney disease," said the study's lead author Helen Vlassara, MD, Professor and Director of the Division of Experimental Diabetes and Aging at Mount Sinai School of Medicine.
"This suggests that oxidants may play a more active role than genetics in overwhelming our body's defenses, which we need to fight off disease. It has been said that nature holds the power, but the environment pulls the trigger. The good news is that unlike genetics, we can control oxidant levels, which may not be an accompaniment to disease and aging, but instead due to the cumulative toxic influence of AGEs," said Dr. Vlassara.
Calorie restriction is going to reduce your intake of AGEs and glucose, of course, even if you manage to keep eating exactly the same foods as you did before. Though in practice most practitioners find they have to drop highly processed or sugared foods from their diet in order to meet the calorie limits. So some presently unknown fraction of the health and longevity benefits of calorie restriction may stem from lowered intake of AGEs and glucose.