PHYTOCHEMICALS - VITAMINS OF THE FUTURE?
Ohio State University Extension Fact Sheet
Family and Consumer Sciences
1787 Neil Avenue, Columbus, Ohio 43210
HYG-5050-98
By 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 disease 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 provide a 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: Non-nutrient 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 |
Composite Plants
Artichoke |
Silymarin |
Citrus Fruits
Oranges
Lemons
Grapefruit
Limes |
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 not listed here
and many
are 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 SIMPLY TAKE A SUPPLEMENT 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 vegetables 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.
- 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 health care provider 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.
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Molecular Expressions: The Phytochemical Collection With Graphics
