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Phytochemicals


Source:  Ohio State University Extension

Phytochemicals - Vitamins of the Future?, HYG-5050-98
Ohio State University Extension Fact Sheet, Family and Consumer Sciences
1787 Neil Avenue, Columbus, Ohio 43210

Sereana Howard Dresbach
Amy Rossi


Recently, you may have heard the words chemoprevention, nutraceuticals, and phytochemicals in the media. What exactly do these terms mean? With the  ever-increasing interest in improving our health, it is important to understand  these words and understand their function in health care. The information presented here will provide a basis for deciphering the mixed messages that are being delivered in the media, conversations, research, and education.

Research has demonstrated that cancer is a largely avoidable disease. It is estimated that more than two-thirds of cancer may be prevented through lifestyle modification (1). Nearly one-third of these cancer occurrences can be attributed to diet alone, secondary to our American diet of high-fat, low-fiber content. Fruit and vegetable consumption have been consistently shown to reduce the risk of many cancers (2). A major prevention strategy has been the "5 A Day for Better Health" program sponsored by the National Cancer Institute (NCI), encouraging the public to include more fruits and vegetables in their diet. The American Cancer Society has developed guidelines for nutrition and cancer prevention. These guidelines are similar to the Dietary Guidelines for Americans and include the following:

Choose most of the foods you eat from plant sources.
Limit your intake of high-fat foods, particularly from animal sources.
Be physically active. Achieve and maintain a healthy weight.
Limit consumption of alcoholic beverages if you drink at all.

The guideline stating to "choose most of the foods you eat from plant sources" has been recognized for years as important for good health. The Food Guide Pyramid illustrates this recommendation. More importantly, recent research has begun describing properties, specifically chemicals, contained in fruits, vegetables, grains, legumes, seeds, licorice root, soy, and green tea. Chemical compounds found in these foods are being recognized for their potential for protection against heart diasease and cancer. This fact sheet will describe phytochemicals, identify the foods in which they
are found, and suggest ways to obtain them from the diet.

Current "Buzzwords" in Nutrition

Chemoprevention -- Using one or several chemical compounds to prevent, stop, or reverse the development of cancer.
Designer Food -- Processed foods that are supplemented with food ingredients naturally rich in disease-preventing substances (5).
Functional Food -- Any modified food or food ingredient that may providea health benefit beyond the traditional nutrients it contains (6).
Nutraceutical -- Specific chemical compounds in food, including vitamins and additives, that may aid in preventing disease.
Pharmafood -- Food or nutrient that claims medical or health benefits, including the prevention and treatment of disease (7).
Phytochemical --Nonnutrient plant chemicals that contain protective, disease-preventing compounds.

What are phytochemicals?
Phytochemicals are nonnutritive plant chemicals that contain protective, disease-preventing compounds. More than 900 different phytochemicals have been identified as components of food, and many more phytochemicals continue to be discovered today. It is estimated that there may be more than 100 different phytochemicals in just one serving of vegetables (6).

As early as 1980, the National Cancer Institute Chemoprevention Program of the
Division of Cancer Prevention and Control began evaluating phytochemicals for
safety, efficacy, and applicability for preventing and treating diseases.

Researchers have long known that there are phytochemicals present for protection
in plants, but it has only been recently that they are being recommended for
protection against human disease.

Most Commonly Studied Phytochemicals

Food Phytochemical(s)
Allium vegetables
(garlic, onions, chives, leeks)
Allyl sulfides
Cruciferous vegetables
(broccoli, cauliflower,
cabbage, Brussels sprouts,
kale, turnips, bok choy,
kohlrabi)
Indoles/glucosinolates
Sulfaforaphane
Isothiocyanates/thiocyanates
Thiols
Solanaceous vegetables
(tomatoes, peppers)
Lycopene
Umbelliferous vegetables
(carrots, celery, cilantro,
parsley, parsnips)
Carotenoids
Phthalides
Polyacetylenes
Compositae plants (artichoke) Silymarin
Citrus fruits
(oranges, lemons, grapefruit)
Glucarates
Monoterpenes (limonene)
Carotenoids
Other fruits (grapes, berries,
cherries, apples, cantaloupe,
watermelon, pomegranate)
Ellagic acid
Phenols
Flavonoids (quercetin)
Beans, grains, seeds
(soybeans, oats, barley, brown
rice, whole wheat, flax seed)
Protease inhibitors
Flavonoids (isoflavones)
Phytic acid
Saponins
Herbs, spices (ginger, mint,
rosemary, thyme, oregano,
sage, basil, tumeric, caraway,
fennel)
Gingerols
Flavonoids
Monoterpenes (limonene)
Licorice root
Green tea
Polyphenols
Glycyrrhizin Catechins

There are also hundreds more phytochemicals existing and in need of discovery!

How are they beneficial?

Although phytochemicals are not yet classified as nutrients, substances
necessary for sustaining life, they have been identified as containing
properties for aiding in disease prevention. Phytochemicals are associated with
the prevention and/or treatment of at least four of the leading causes of death
in the United States -- cancer, diabetes, cardiovascular disease, and
hypertension (7). They are involved in many processes including ones that help
prevent cell damage, prevent cancer cell replication, and decrease cholesterol
levels.

Specifically, the economic cost of cancer to society was estimated to be about
$104 billion in 1997 (8). With health-care costs being a major issue today, it
would be cost effective to continue the research needed to help promote the
awareness and consumption of phytochemicals as a prevention strategy for the
public.

Can I just take a pill containing these substances?
Americans spend approximately $2-2.5 billion a year on vitamin/mineral
supplements (9). It should be expected that extracted phytochemicals will be, if
not already, available for consumer purchasing. Consumption of supplements
containing phytochemicals will only provide selected components in a
concentrated form, not the diversity of compounds that occur naturally in foods
(10). It is important to continue the effort to encourage increased fruit,
vegetable, and grain consumption to acquire the benefits of phytochemicals
versus simply ingesting a pill containing these substances. Researchers continue
to investigate the interactions of phytochemicals naturally present in food. It
would be difficult to extract phytochemicals from plants for supplement use
before understanding the synergistic effect of all phytochemicals present.

Are there any negative effects?
Individual phytochemicals are being evaluated for their safety and effectiveness
in regard to disease prevention. Although most studies support positive
outcomes, there are a few studies involving animals that show possible
detrimental effects. These studies involve animals and specific extracted
phytochemicals in high dosages. The safety of consuming large amounts of fruits,
vegetables, and grains is not presently a concern. The research question being
asked is: "Should one increase the intake of a particular plant food containing
phytochemicals, and how much should they increase it?" Obviously, like any other
newly discovered chemical, there is a need for further investigation for
potential health benefits and possible health risks. Optimal levels of
phytochemicals have yet to be determined. In addition, requirements during
disease states may differ from requirements for prevention of heart disease and
cancer. Individual recommendations in terms of requirements for different
genders, age groups, body types, and so forth also need further study.
How can I incorporate more phytochemicals into my diet?
First, it is important for Americans to become aware of their lack of
consumption of fruits, vegetables, and grains. The average American consumes
only one serving of vege-tables and one serving of fruit each day (11). In one
survey, one in every nine Americans ate no fruit or vegetable on the day they
were interviewed (12).
Increasing the consumption of plant products in one's diet should not be
difficult or time consuming. There are plenty of simple strategies for
increasing dietary fruits, vegetables, and grains, including the suggestions
below:
Keep fruits and vegetables (fresh, frozen, and canned) stocked and in sight.
Reach for juice instead of coffee or soda.
Add chopped fruit to cereal, yogurt, pancakes, muffins, or even a milkshake.
Snack on fresh chopped carrots, celery, broccoli, cauliflower, and peppers
(purchase at a salad bar to save time).
Add fresh greens, carrots, celery, parsley, tomatoes, and/or beans to your
soups.
Store dried fruit (apricots, dates, raisins, and more) for a quick snack at
home or work.
There are also several other easy methods for increasing fruits, vegetables, and
grains in your lifestyle. Why not challenge yourself and create one of your own?
Good Luck!
Conclusion
It was once stated that our health is a "gift" -- a largely controllable gift
(13). We can control this gift through lifestyle choices of our own. These
choices include the foods we choose to eat.
Research has demonstrated the tremendous potential of phytochemicals in regard
to prevention and treatment of disease. Now, it is the responsibility of not
only health-care professionals, but also individuals to begin the conscientious
effort of improving their diet. Even though phytochemicals are readily available
in today's food supply, it is highly possible that future foods may undergo
bioengineering or fortification to enhance naturally occurring phytochemical
concentrations. This would make it even easier to incorporate phytochemicals in
the diet.
The research involving phytochemicals is promising, but with any newly
discovered chemical, it is recommended that further studies be conducted. This
fact sheet was designed to introduce the discovery and importance of
phytochemicals. It is in no way intended to replace your health-care provider's
recommendations. As with any health recommendation, it is advisable to check
with your physician before adapting any lifestyle changes.
References
1. Oliveria, S. A. et al. 1997. The Role of Epidemiology in Cancer Prevention.
The Soc for Exp Bio and Med 216:142-150.
2. Block, G. et al. 1992. Fruit, vegetables, and cancer prevention: A review of
the epidemiologic evidence. Nutr Cancer 18:1-29.
3. Mirvish, S. S. et al. 1975. Induction of mouse lung adenomas by amines or
ureas plus nitrite and by N-nitoso compounds: effect of ascorbate, gallic acid,
thiocyanate, and caffeine. J Natl Cancer Inst 55:633-636
4. Thomas, P. R., R. Earl. Eds. 1994. Opportunities in the Nutrition and Food
Sciences, Research Challenges and the Next Generation of Investigators. National
Academy Press.
5. Bloch, A. et al. 1995. Position of the American Dietetic Association:
Phytochemicals and functional foods. JADA.95: 493-496.
6. Polk, Melanie. 1996. Feast on Phytochemicals. AICR newsletter. Issue 51.
7. Bloch, A. et al. 1995. Position of the American Dietetic Association:
Phytochemicals and functional foods. JADA.95: 493-496.
8. American Cancer Society. Cancer Facts & Figures 1997. Atlanta, GA: American
Cancer Society.
9. Reynolds, R. D. 1994. Vitamin supplements: current controversies. J Am Coll
Nutr 13(2): 118-126.
10. Bloch, A. et al. 1995. Position of the American Dietetic Association:
Phytochemicals and functional foods. JADA.95: 493-496.
11. Craig, W. 1996. Phytochemicals: Guardians of our health. JADA. 97(10):
S199-S204.
12. Craig, W. 1996. Phytochemicals: Guardians of our health. JADA. 97(10):
S199-S204.
13. Malaspina, Alex. 1996. Functional Foods: Overview and Introduction. Nutr
Reviews 54(11): s4-s10.