The World's Healthiest Foods

What is the Special Nutritional Power found in Phytonutrients?

Plant foods have long been known to promote health and wellness. Cultures whose diet primarily features plant-based foods such as fruits, vegetables, whole grains and legumes have been found to have increased longevity and reduced rates of the many cancers and chronic diseases so common in populations consuming the standard American diet.

Researchers traditionally have attributed the health-promoting affects of plant foods to their comprehensive array of vitamins, minerals, and fiber. More recently, however, research studies are uncovering a new story. Plant foods contain thousands of other compounds in addition to the macronutrients (complex carbohydrates, proteins, fats, and fiber), and the micronutrients (vitamins and minerals). These many other compounds are collectively known as phytonutrients (phyto=plant). Simply put, phytonutrients are active compounds in plants that have been shown to provide benefit to humans when consumed.

Phytonutrients provide plants with protection from the environmental challenges they face, such damage from ultraviolet light, and, when we consume plants rich in phytonutrients, they appear to provide humans with protection as well. Investigating the ways in which phytonutrients provide this protection is one of the most exciting areas in nutrition research today, and recent findings are providing science-based explanations as to how plant foods support our health and wellness.

What are phytonutrients?

Phytonutrients are plants' home security services--think of them as the Plant Police, Fire Department and Coast Guard. As defenders, phytonutrients protect their plant from free radical attack from excess ultraviolet radiation and from predator pests. And phytonutrients do their job with style, providing plants with their sensory characteristics such as their color, flavor and smell.

Unlike us, plants can't move, put on a fan or air conditioning when it gets too hot, or put on sunscreen or sunglasses. But, even more than we, plants are exposed to damaging radiation, toxins, and pollution, and this toxic exposure results in the generation of free radicals within their cells. Free radicals are reactive molecules that can bind and damage proteins, cell membranes and DNA. Since plants can't move away from these insults, nature has provided them with a means of protection: they can make a variety of types of protective compounds--the phytonutrients. Like plants, we're exposed to ultraviolet radiation or pollution, we also generate reactive, free radicals, and although we cannot produce our own phytonutrients, when we consume plants, their phytonutrients also protect us against damage from these free radicals. In fact, researchers at the Tufts University Human Nutrition Research Center on Aging have determined that phytonutrients (and perhaps conventional nutrients as well) in green leafy vegetables may help protect our heart rate from potential disruption by air-polluting particles that cause free radical damage to parts of the nervous system that help regulate heart rate. There's a chance that phytonutrients in cruciferous vegetables and non-citrus fruits (like berries and plums and grapes) might work in this exact same way.

Most plants use sunlight as an energy source. Although to the eye sunlight appears as a single, clear, bright force, it is actually made up of many different wavelengths, some of which the plant captures for the generation of energy. Others, however, are wavelengths from which the plant needs protection. Each plant contains literally thousands of different phytonutrients that can act as antioxidants, providing protection from potentially damaging free radicals. Many of these compounds also provide the plants with color, their different colors each reflecting a different variety of protection they provide.

Plants Contain Thousands of Phytonutrients

If a plant was only one color, with no shades or variations in that color, it would only be able to receive and protect against one specific wavelength of light. A plant with several different colors is like a television set with an antenna, and a plant with many different colors is like a television with a satellite dish. Most plants have a satellite dish's worth of colors - even ones that look very green to us when we eat them. Like the primer used beneath a coat of paint, these other colors are simply overshadowed by the primary color that we see.

How are Phytonutrients Classified?

Some researchers estimate up to 40,000 phytonutrients will someday be fully catalogued and understood. In just the last 30 years, many hundreds of these compounds have been identified and are currently being investigated for their health-promoting qualities. At research organizations like the National Institute of Cancer, and at many universities around the world, different individual phytonutrients are being studied to identify their specific health benefits.

Phytonutrients are classified by their chemical structure. This classification is extensive and can be confusing since many of the phytonutrients appear to provide similar types of protection. Still, these names help scientists differentiate between phytonutrients' different chemical structures. Because there are so many compounds, phytonutrients are also lumped together in families depending on the similarities in their structures. Names such as terpenes are used to describe carotenoids, some of which are precursors to vitamins A, and which provide the orange, red and pink colors in foods such as carrots, tomatoes, and pink shellfish; limonoids, which are found in citrus fruits and provide them with their distinctive smell; and coumarins, natural blood thinners found in parsley, licorice and citrus fruits.

The phenols, or polyphenols (poly=many) is another family of phytonutrients that has received much research and discussion in the scientific literature. In fact, some of the most talked about phytonutrients are in this family. They include the anthocyanidins, which give blueberries and grapes their dark blue and purple color, and the catechins, found in tea and wine, which provide the bitter taste as well as the tawny coloring in these foods. Flavonoids are also commonly considered phenols, although the term "flavonoids" can refer to many phytonutrients. Lastly, the isoflavones are usually categorized as members of this family. Isoflavones, which are found in soy, kudzu, red clover, flax and rye, have been researched extensively for their ability to protect against hormone-dependent cancers, such as breast cancer.

Other phytonutrients include the organosulfur compounds, such as the glucosinolates and indoles from brassica vegetables like broccoli, and the allylic sulfides from garlic and onions, all of which have been found to support our ability to detoxify noxious foreign compounds like pesticides and other environmental toxins. Organic acids are another common family of phytonutrients and include some powerful antioxidants, like ferulic acid, which is found in whole grains.

Phytonutrients in Fruit - Anthocyanidins

With over two thousand known plant pigments presently identified, the chemicals that give foods their colors may also translate into vibrant health. Notable among these phytonutrient pigments are the bioflavonoids known as anthocyanidins. These are the purple-blue pigments that give fruits such as blueberries, blackberries, raspberries, black currants, and red and purple grapes their unique coloration, and which protect them from the damaging effects of oxidation. Anthocyanidins' antioxidant properties are now being investigated by health care researchers who are determining that these phytonutrients not only support the health of plants, but can support the health of humans as well.

As researchers confirm that metabolites of oxidation, known as free radicals, are at the root of the progression of both chronic diseases (such as arthritis, atherosclerosis, diabetes and cancer) and other signs of aging, such as the loss of skin elasticity and cognitive function, antioxidants are gaining an ever more important place in health promotion. Among the antioxidants, anthocyanidins have been found to have some unique features. They are able to protect cells and tissues from free radical damage in both water-soluble and fat-soluble environments. And, their free radical scavenging capabilities are thought to be more potent than many of the currently well-known vitamin antioxidants; anthocyanidins are estimated to have fifty times the antioxidant activity of both vitamin C and vitamin E.

Much of the research on anthocyanidins has focused on their ability to protect collagen, such as the collagen that makes up our joints or provides the structure to our capillaries, from the destructive effects of free radical damage. This protection of capillary integrity manifests in the ability of anthocyanidins to reduce the fragility and permeability of these small blood vessels. Anthocyanidins are therefore thought to be able to reduce edema (swelling) as well as vascular conditions such as varicose veins and hemorrhoids. Their ability to inhibit the degradation of collagen found in blood vessels and cartilage has led researchers to propose that anthocyanidins may play a role in the prevention of atherosclerosis and arthritis.

How much of these phytonutrients should I take?

Although research is supporting their significant health benefits, phytonutrients are presently considered "non-essential" nutrients. Unlike vitamins and minerals, there are no RDAs or DRIs for them. One reason for the difficulty in setting a level is that there are so many of these phytonutrients that appear to provide health benefits; hundreds are presently being researched for their health-promoting effects. Another reason for the difficulty in setting standards for consumption is that many of these phytonutrients have similar activities. Instead of a lot of one specific compound, it may be more important to have a certain level of a family of compounds, but you can have different amounts of the individual compounds and still get the health benefit.

Finally, new research is finding that many of these phytonutrients act synergistically; that is, they help each other and provide more benefit when taken with other phytonturients than alone. This is a major reason for eating whole foods rather than taking an individual supplement of beta-carotene or vitamin C. The whole food can contain not only the beta-carotene or vitamin C, but also other phytonutrients that act synergistically to support even more benefit to your health.

Many health care practitioners and public health organizations have realized the importance of these vital nutrients and suggest that people eat a varied diet concentrated in fruits, vegetables, whole grains and legumes to obtain a high level of phytonutrients. Maybe what our Grandmothers used to say is right: "Eat a colorful meal!" With a range of colors in your food, and a high level of vegetables, fruits, whole grains and legumes in your diet, you will obtain a beneficial level of phytonutrients to support your good health.

Conclusion

The array of phytonutrients offered by plant-based foods such as fruits, vegetables, whole grains and legumes further supports the fact that these foods can make important contributions to our health. Although they are officially considered "non-essential nutrients," meaning that their intake is not necessary for survival, phytonutrients seem to truly be essential for the sustenance of a good life, one full of health and abundant energy. Hopefully, one day as the accepted nutrition paradigm changes from preventing outright deficiencies to one that emphasizes that foods can help prevent disease and promote longevity, the true importance of these phytonutrients will be recognized.

References

Park SK, Tucker KL, O'Neill MS et al. Fruit, vegetable, and fish consumption and heart rate variability: the Veterans Administration Normative Aging Study. The American Journal of Clinical Nutrition. Bethesda: Mar 1, 2009. Vol. 89, Iss. 3; pg. 778-786.