Garlic:
Of all plants with medicinal purposes, garlic is probably the most widely hailed. It’s been said to bolster the immune system, prevent cancer and heart disease, and act as an antibiotic. Even ancient Greek literature abounds with anecdotes about the wondrous qualities of garlic. It’s one of those foods that have more than nutritional benefits. The allium family – including garlic, onions and leeks – contains a chemical called allicin that may curb cancers of the gastrointestinal tract.
Although garlic’s role as a cancer fighter has not passed rigorous testing, the evidence that it can lower cholesterol is strong. A survey of 16 clinical trials found garlic lowered cholesterol by 12 percent. Not all supplements work as well as plain garlic, so stick with the fresh stuff.
How much do you need? To lower your cholesterol, try one or more cloves a day, chopped or crushed.

Spinach:
Remember Mom’s admonition to eat carrots because they’re good for your eyes? Mom probably should have promoted spinach instead. Dark green leaves like spinach, collard greens and kale contain lutein and zeaxanthin, phytochemicals that may protect your eyes as you age.
A study in the journal of the American Medical Association found that, people 55 and over who ate 5 to 6 servings of spinach or collard greens a week were one-eighth as likely to suffer from macular degeneration (a leading cause of blindness) as those who ate one serving or less a month.
How much do you need? Try to eat 5-6 cups a week.

Broccoli and Its Cousins:
Evidence is mounting that broccoli and related vegetables (such as cabbage, cauliflower and Brussels sprouts) lower the risk of lung, stomach and other cancers. The substances that make these vegetables so healthy, aside from vitamins, could be glucosinolates. One chemical in this group – called indole-3-carbinol (I3C) – may protect against breast cancer. In fact, researchers are examining the possibility of putting I3C in a pill to combat breast cancer. Still, it’s too early to say whether this or any other food will truly prevent the disease.
How much do you need? Aim for several 1/2-cup servings a day.

Citrus Fruits:
Oranges, lemons, limes and grapefruit are excellent sources of vitamin C, folate and fiber (all linked to reduce cancer risks). But their oil is also high in a lesser-known chemical called limonene, which has been shown to fight tumors in laboratory animals. Researchers are testing a limonene derivative in-patients with advanced cancers. So far the final word’s not in about limonene’s benefits. Most of it is found in the pulp and peelings of citrus, but you can also get a high concentration in juice. So drink up.
How much do you need? Nutritionists recommend 2-4 servings of fruit (3/4 cup juice or 1/2 cup of fruit per helping) daily.

Grapes and their juices:
The news that drinking wine – particularly red wine – is associated with a lower risk of heart disease has received a big play. In fact, heart disease takes the least toll in countries where people drink it the most – France, in particular. Scientists suspect most of the benefits come from nonalcoholic flavonoids in red wine, particularly phenolics in grape skins. Some benefits of wine may also come from the alcohol, which raises "good" HDL cholesterol. Until more studies come in, scientists agree: don’t take up drinking to protect your heart. Since alcohol is linked to higher risks of some cancers, stick with purple grape juice or eat red and black grapes, which have more phenolics than green grapes.
How much do you need? Nutritionists suggest 2-4 servings of fruit a day. Drink wine in moderation.