Protection from Plants…defenders against disease

By Brenda Davis, RD

 

There is no doubt that the food we put into our bodies dramatically alters our risk for numerous chronic diseases, including cardiovascular diseases, certain types of cancer and type 2 diabetes. While most people understand this connection, they are often confused about the most powerful steps that they can take to reduce their risk. Many people do a reasonable job of cutting back on damaging dietary components such as saturated fat, cholesterol and trans fatty acids. However, they assume that once they get rid of the worst offenders, there is nothing more that can be done to further improve their diet. They are wrong. While getting rid of unhealthy foods is an extremely important first step, it is only half the battle. Fortunately, the other half is much more pleasant—adding a wide variety of delightfully delicious and nutritious plant foods. These plant foods offer a host of protective dietary components including fiber, antioxidant nutrients, essential fatty acids and a host of phytochemicals. This article will focus on phytochemicals and how you can maximize your protection from what may be among our greatest allies in our fight against disease.

 

Phytochemicals are natural substances found in all plants that regulate growth, defend against attacks by insects or fungi, and provide flavor, color, texture, and odor. Luckily for us, when we eat plants, these powerful little protectors go to work on our behalf, and their potential for human health is simply remarkable. 

 

To begin, many phytochemicals are strong antioxidants, quenching destructive free radicals. Others have tremendous anticancer activity, blocking tumor formation, reducing cell proliferation, and inducing enzyme systems that help rid the body of potent carcinogens. Phytochemicals also protect against cardiovascular disease by helping to reduce the formation of cholesterol, lower blood pressure, decrease blood cholesterol levels, decrease platelet stickiness, reduce blood clot formation, open blood vessels, and decrease damage to blood vessel walls.
 
Which foods are the most efficient phytochemical factories? Vegetables and fruits stand out as being particularly noteworthy, although legumes, grains, nuts, and seeds are also excellent sources. Choosing a wide variety of colorful, whole plant foods is your key to a phytochemical-rich diet. There are, of course, certain foods that can transform your diet into a tremendous phytochemical feast. Among the most outstanding are dark greens (such as kale, collards, and spinach), crucifers (like broccoli and broccoli sprouts), and, of course, garlic, tomatoes, blueberries, citrus fruits, flaxseeds, and soybeans. Let’s take a look at some of the most impressive among these.

 

Phytochemical Superstars:

 

• Kale. Found to have the greatest antioxidant activity when rated against 19 other vegetables, kale is rich in lutein, a phytochemical that protects the eyes from macular degeneration, the leading cause of blindness in North America. It is also high in beta-carotene, (antioxidant), indoles (help eliminate toxic compounds), sulforaphanes (anti-carcinogens), and quercetins (anti-inflammatory agents).

 

• Broccoli. With a similar complement of phytochemicals to kale, broccoli is also noted for its indole content (helping to shift estrogen-production to a less potent form, a protective factor relative to hormone-related cancers). Interestingly, broccoli sprouts contain anywhere from 10 to 100 times more sulforaphane than broccoli, comparing weight for weight.

 

• Garlic. With a unique phytochemical makeup, garlic is loaded with allium compounds. These phytochemicals help to lower blood pressure, reduce the stickiness of blood cells, dilate blood vessels, and destroy cancer cells. The allium compounds also have immune-stimulating, antibacterial, antifungal, antiyeast, and antiasthmatic activity.

 

• Tomatoes. Tomatoes get their red color from the exceptional amount of lycopene they contain. Lycopene has strong antioxidant properties, and several studies have suggested that it may be effective in protecting against prostate cancer and/or slowing the growth of prostate tumors. As well, there is some compelling evidence that lycopene is a powerful protector against the development of artery and heart disease.

 

• Blueberries. In a study by the USDA’s Center for Aging at Tufts University, the Oxygen Radical Absorbance Capacity, or ORAC (ability to quench free radicals), of over 40 vegetables and fruits was measured. Of all the foods, blueberries came out on top! The primary active component in blueberries is a phenolic compound and powerful antioxidant called anthocyanin. This substance gives blueberries their rich blue color. Blueberries contain several other phenolic compounds, including flavonols and phenolic acids. In addition to their antioxidant activity, blueberries have been found to protect against urinary tract infections, improve “tired eyes,” and possibly reduce the overall effects of aging through their potent antioxidant activity.

 

• Citrus fruits. A single orange contains over 170 different phytochemicals, including 60 flavonoids, 40 limonoids, and 20 carotenoids. Flavonoids are strong antioxidants with significant anticancer, and anticardiovascular disease activity, while limonoids help to reduce cholesterol levels and stimulate detoxifying enzymes.

 

• Soybeans. These beans provide a rich plant source of protein and plant sterols, as well as phytoestrogens such as lignans and isoflavones. The principle isoflavones in soy are genestein and daidzein. These isoflavones are powerful antioxidants and very effective inhibitors of the tyrosine kinase enzyme—a potent tumor promoter. Research suggests that isoflavones may provide protection against heart disease, certain forms of cancer, and osteoporosis.

 

• Flaxseeds. The champions of the nut and seed world, flaxseeds are our richest known source of lignans (potent anticarcinogens), with over 100 times the lignans of most other plant foods. They also boast the highest alpha-linolenic acid content of any food—57% of the fat in flaxseeds is omega-3 fatty acids. Omega-3 fatty acids fight cancer and cardiovascular disease. Like other nuts and seeds, flaxseeds also contain flavonoids, phenolic acids, phytic acids, and tocotrienols (a type of vitamin E).

 

• Green tea. With its polyphenol and catechin content, green tea is an up and coming phytochemical superstar. It is especially rich in epigallocatechin gallate, a potent anticarcinogen and powerful antioxidant.

 

It is important to note that refining foods can dramatically diminish phytochemical content. Refining a grain of wheat removes 95% of the phytochemicals! While many people assume that cooking will damage phytochemicals, that is not necessarily so. In many cases cooking actually increases the availability of phytochemicals. For example, lycopene is far better absorbed from cooked tomatoes than from raw tomatoes, especially when oil is used in the recipe. Cooking can also alter the structure of phytochemicals, resulting in very different health effects. For example, when garlic is cooked in water, vinyldithiins (antiasthmatics) are produced, while when cooked in oil, ajoenes (inhibitors of chemicals that increase inflammation and blood pressure) are formed. There is little question that if you want to maximize phytochemicals in your diet, it may be best to include a variety of both raw and cooked foods.

 

Many people wonder if they can just pop a pill to get their phytochemicals. For a host of reasons, it looks like we are much better off eating the whole food than simply relying on an extract. Studies looking at the effects of single phytochemicals have been rather mixed, and some downright discouraging. One of the reasons may be that phytochemicals often work synergistically with one another, and the collaborative action of two or more chemicals is sometimes needed to produce the desired effect. At this time, we just do not know enough about the complicated interactions of these dietary components to be confident about turning them into pills. Besides, whole foods come packaged with fiber, vitamins, minerals, plant sterols, and other protective components, and they are infinitely more pleasurable to consume!

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