There are a lot of disagreements about what exactly is "optimal nutrition", but the one area where you'll see the most agreement is vegetables. Eating a lot of them creates a lot of health benefits. Risk of cancer, metabolic syndrome, osteoporosis, and more - all dramatically reduced. We know that vegetables are nutritionally dense and alkaline to the body, both beneficial characteristics. But little is known about the specific mechanisms by which they may prevent cancer.
Researchers have recently identified one of the ways in which this works. Pectin, a fiber found in all fruits and vegetables (and used to make jam), has a fragment that binds to and is believed to inhibit a protein called galectin 3 that plays a role in all stages of cancer progression.
The best way to increase your vegetable intake is to regularly eat large salads with a wide variety of vegetables. Add some fish or lean meat and dressing made with monounsaturated fat (such as olive oil) or omega-3 fat (such as flax oil), and you've got a perfect meal.
http://www.fasebj.org/cgi/content/abstract/fj.08-106617v2
