Phytochemicals aren't exactly foremost in the minds of most health-conscious consumers -- certainly not to the same extent as fat, cholesterol, calcium and even antioxidants. Judging from the resources that researchers are now devoting to this group of chemicals, though, it may soon become the next nutritional buzzword.
Will food designers be creating products that cash in on what some see as the next consumer craze? As it stands, the food industry is already under fire within some circles for failing to market better-known functional food components -- like fiber, vitamins and minerals -- more aggressively.
Ironically, the Dietary Supplement Health and Education Act of 1994 -- which some saw as a means to loosen the regulatory handcuffs for the food industry, as well as the supplement industry -- may be of little help. In fact, some experts say that by failing to spell out a regulatory framework for nutraceuticals, DSHEA may make it more difficult to market the phytochemical benefits of food products. Instead, consumers may be flocking to health food stores to purchase phytochemicals-in-a-pill.
Exactly what is a phytochemical? As the name indicates, phytochemicals are chemicals that are found in plants. They aren't considered nutrients because they have no inherent nutritive value -- as opposed to vitamins or minerals, for example. Often, they do impart flavor or color to the plant. And data is stacking up, mostly in the form of epidemiological and animal studies, that they may do even more important things in the human body.
The incredible isoflavones
The isoflavones found in soy, particularly genistein and daidzein, have been commanding a great deal of space in the medical press recently -- and for good reason. Many studies have suggested a protective role against certain cancers. Also, the results of a major meta-analysis published last summer were in keeping with what some researchers have long suspected: that soy consumption could be an important weapon against serum cholesterol.
That analysis, published Aug. 3, 1995, in the New England Journal of Medicine, examined the results of 38 clinical studies that had been conducted over the past 17 years. Under the direction of James Anderson, M.D., a professor of medicine and clinical nutrition at the University of Kentucky, Lexington, researchers found that consuming soy protein significantly decreases serum cholesterol levels without significantly affecting the HDL cholesterol (high-density lipoprotein, or "good" cholesterol) that protects against heart disease.
According to their analysis, daily consumption of 17 to 25 grams of soy protein was associated with reductions in serum cholesterol in 34 out of the 38 studies. The average total cholesterol reduction was 9.3%; LDL cholesterol (low-density lipoprotein, or "bad" cholesterol) was reduced 12.9%; and HDL increased by 2.4%.
As for the anti-cancer properties of soy, the evidence thus far has been generated by epidemiological and animal studies. According to Stephen Barnes, Ph.D., of the University of Alabama, Birmingham, certain Asian populations have a four- to ten-fold lower incidence of death from breast and prostate cancer than Americans. They also consume 20 to 80 mg of genistein daily, mostly from soy protein, whereas Americans consume only 1 to 3 mg.
Animal studies appear to have corroborated the connection, Barnes noted in a 1995 article in the Journal of Cellular Biochemistry. In one such study, the consumption of soybeans was shown to reduce the incidence of mammary tumors in rats. In another, genistein was shown to inhibit the incidence, size and multiplicity of mammary tumors in rats.
Equally intriguing is evidence that these same compounds reduce the risk of osteoporosis and the severity of menopausal symptoms, possibly by preventing the body's own estrogen from binding to cell receptors.
Granted, America's eating habits would have to change dramatically to incorporate the levels of soy protein that the Asian populations consume. Anderson, the lead author of the cholesterol meta-analysis, recommended 17 to 25 grams a day -- the amount in one 10- or 11-oz. block of tofu.
The results of clinical trials now underway may soon provide enough incentive for Americans to change their eating habits -- and for food designers to come up with the products to help them do so. For example, several chemoprevention trials have begun, or are being planned, using SUPRO® brand isolated soy protein from Protein Technologies International. The effects of the isolate on several cancers, including breast, colon and prostate, are being studied.
At the University of Illinois' Functional Foods for Health program, Urbana, IL, researchers are now conducting dietary intervention trials to study whether soy proteins can protect against osteoporosis. The phytoestrogens in soy are believed to bind to human cell receptors in the same way as the body's own estrogens, which may account for their apparent protective effect against osteoporosis and estrogen-dependent cancers.
"These estrogens bind weakly, but strong enough to keep our estrogens from binding," explains program director Clare Hasler, Ph.D.
The case for carotenoids
The controversy continues to escalate over the effectiveness of vitamin A and beta-carotene against cancer and heart disease -- at least in supplement form. At the same time, evidence is building that other carotenoids in fruits and vegetables have myriad health benefits.
We know of some 500 carotenoids; about 10% of these are converted to vitamin A in the body. (This conversion ability is what accounts for beta-carotene's ubiquitous presence in vitamin supplements and its inclusion in so many clinical trials. Several health risks have been attributed to excessive doses of vitamin A; beta-carotene supplements are believed to be a safer way to achieve antioxidant and other benefits.)
Many epidemiological studies have pointed to correlations between consumption of fruits and vegetables and a reduced risk of certain cancers, as well as heart disease, macular degeneration and other conditions. Some studies have taken the connection a step further by attributing the risk reduction to specific carotenoids in the fruits and vegetables.
One recent study that's garnered quite a bit of attention was published Dec. 6, 1995, in the Journal of the National Cancer Institute. In the article, Harvard Medical School researchers suggested that intake of lycopene or other compounds in tomato products may reduce the risk of prostate cancer.
Although lycopene is not converted to vitamin A in the body, the researchers explained, "it is the most efficient scavenger of singlet oxygen among the common carotenoids and is the predominant carotenoid in plasma and in various tissues, including the prostate gland."
This study was part of the ongoing Health Professionals Follow-Up Study, which has examined the fruit and vegetable consumption of more than 47,000 men over nine years. Subjects who ate 10 or more servings of tomatoes, tomato paste and pizza per week were 45% less likely to develop prostate cancer than men with low intakes of those foods; those who consumed four to seven servings were 20% less likely.
Interestingly, products made with tomato paste had a greater protective effect than the tomatoes themselves -- hence the headlines in the consumer media proclaiming the new-found health benefits of pizza.
The flavonoid fix
Health professionals have welcomed recent explanations of the infamous "French paradox" ambivalently, to say the least. Certainly, more than a few consumers were happy to learn that all the wine the French drink may protect them from heart disease, which could normally ensue from so much consumption of saturated fats.
Setting aside the potential risk increases for other public health concerns -- such as alcoholism, death from drunk driving, and possibly even breast cancer -- several epidemiological studies have indicated a correlation between consumption of wine and a reduced risk of heart disease. Researchers theorize that flavonoids and other polyphenolic antioxidants, while not actually reducing serum cholesterol levels, may reduce platelet activity, thereby minimizing blood clotting.
Recently, researchers have been attributing these effects mostly to red wine, which contains more of the whole grape than white wine. Because the compounds are more concentrated than in the whole fruit, some say, moderate amounts of wine may be more beneficial than the amount of grapes one could reasonably consume at a sitting. According to some researchers, it also stands to reason that grape juices contain similar concentrations.
Meanwhile, some studies have suggested that similar compounds in green and black teas may have the same anti-clotting effect. Epidemiological evidence has indicated a correlation between the reduced risk of heart disease among Chinese and Japanese populations and their high rate of tea consumption. Clinical trials should shed more light on whether these benefits can be attributed to the tea, or to the generally low-fat Asian diet.
Epidemiological evidence that the compounds in tea can reduce the risk of certain cancers has been spotty, although animal studies have been more conclusive.
Those amazing allicins
Of all the phytochemicals now being researched, the allicins found in onions and garlic are the most familiar to consumers. Since the 1950s, more than 1,200 papers have been published on the health benefits of garlic, according to Paul Lachance, Ph.D., chairman of the food science department at Rutgers University, New Brunswick, NJ.
Epidemiological and animal studies have attributed numerous health benefits to the compounds in garlic. Among these are the ability to reduce serum cholesterol and LDL cholesterol, as well as platelet activity. Allicin and similar compounds also seem to have antibacterial and antifungal properties; in fact, garlic has been used for centuries among Asian populations as a weapon against infections.
Large-scale studies in China and Italy have indicated a link between garlic consumption and reduced risk of stomach cancer, and the Iowa Women's Health Study has associated garlic with a reduced risk of colon cancer. Again, animal research has tended to confirm most of these epidemiological results, but what's needed now is definitive evidence from human clinical trials.
With so many potential benefits being attributed to garlic, it's not surprising that supplement manufacturers have been marketing garlic tablets and capsules aggressively. What consumers may not realize, though, is that the content of the active ingredients in these supplements can vary widely from brand to brand -- and possibly from batch to batch. There is no official methodology for assaying the levels of allicins or of most of the other phytochemicals -- and therein lies the regulatory rub for food designers.
For most of the vitamins, minerals and other nutrients that are required on the labels of food products, there are methods of assaying that are approved by AOAC International. Traditionally, AOAC-approved methods have been accepted by the U.S. Food and Drug Administration and the U.S. Dept. of Agriculture.
For substances like phytochemicals, which are not required on the label, there often aren't any officially approved methods. Individual manufacturers may standardize these substances, but in the absence of AOAC-approved methods, the consumer has no assurance that the product contains what it claims.
Presumably, if supplement or food manufacturers start making health claims or even structure/function claims for a particular phytochemical, it would attract FDA's attention. A simple content claim would be unlikely to do so in the current anti-regulatory climate, unless harmful effects were to be attributed to the substance. Understandably, though, companies may be reluctant to make claims that still might come under the agency's scrutiny -- especially for phytochemicals or other substances for which there are few, if any, standardized methods of assay.
This regulatory conundrum is a "chicken-and-egg syndrome," in the words of Audra Davies, director of product development at Watson Foods Co.'s nutritional products division. It's also one reason why the U.S. food industry has not jumped onto the nutraceutical bandwagon as enthusiastically as have other countries, such as Japan.
Some supplement manufacturers, however, have been considerably quicker to market the benefits of phytochemicals. A few are claiming to offer the advantages of several servings of fruits or vegetables within a very concentrated form. And they are doing so despite the fact that the effects of processing methods on phytochemicals -- such as concentrating, freeze-drying or even extraction -- have yet to be determined.
Manufacturers who are rushing their supplements to market without standardizing their contents are guilty of "irresponsible marketing," according to Lachance, of Rutgers. "They're going to hurt the whole industry," he says.
Setting some standards
An ongoing project at USDA's Food Composition Laboratory in Beltsville, MD, may prove to be the first step toward solving the dilemma. Under the direction of Gary Beecher, Ph.D., the laboratory is developing analytical technology to measure certain phytochemicals in food products.
For the past few years they've been working with carotenoids in conjunction with the University of Minnesota, Minneapolis, and the Medical College of Virginia at Richmond. Recently, they began working with flavonoids in conjunction with Tufts University, Boston, as well as isoflavonoids in conjunction with Iowa State University, Ames.
The immediate goal is to develop a database for USDA's "Handbook 8." Whether the methods are eventually accepted by the AOAC remains to be seen. As Beecher points out, the phytochemicals they're working with are not yet required on food labels.
As research continues to uncover the health benefits of phytochemicals, food designers can be sure that their counterparts in the supplement industry will continue to capitalize on consumer demand. Their standardization methods will continue to evolve as well.
Many supplement manufacturers are developing increasingly sophisticated technology, according to Paul Bolar, vice president for legal and regulatory affairs at Pharmavite Corp. In addition, the fact that the U.S. Pharmacopeia (USP) is interested in the area may provide incentive for supplement manufacturers to standardize their products.
In January 1995, the USP published its new standards for multivitamins, including methods for assay, dissolution and weight variation measurement, as well as GMP (Good Manufacturing Practices) guidelines. The USP is now interested in doing the same with herbal products and extracts, according to Bolar.
Although the USP is not a government agency, its methods are recognized by FDA. Use of the USP seal is voluntary, but if consumers learn to look for it, the increased credibility could give supplement manufacturers an edge over a slower-moving food industry.
What designers do have in their favor is solid support from health and nutrition professionals, who continue to insist that a balanced, varied diet is the best way to achieve the health benefits of most nutrients -- including phytochemicals.
The fastest way to lose that edge, though, may be to undermine consumer confidence. Everything depends on "doing the right science, if we want to move the whole area of functional foods into the mainstream and out of the health food stores," says Fergus Clydesdale, Ph.D., chairman of the food science department at the University of Massachusetts, Amherst. Otherwise, he says, the ultimate loss will be to the consumer.
Technology Overcomes Processing Obstacles
The party line from nutritionists is that whole foods are usually preferable to processed. There's no fighting it: Vitamin content is usually diminished by processing, and in some cases, dramatically so.
Processing doesn't always have to raise a red flag to consumers, however. Food designers have made great strides in compensating for nutrient losses -- and besides, processed foods sometimes are better than fresh.
"Processing and technology very often are looked at in pejorative terms," says Fergus Clydesdale, Ph.D., of the University of Massachusetts, Amherst. "But processing can concentrate the good ingredients, as well as the bad."
That phenomenon certainly seems to be at work in the case of new research that attributes protective effects against prostate cancer to lycopene, with tomato-based food products having a greater effect than the tomatoes themselves. Other research suggests that the flavonoids in wine are more effective than the raw grapes, if only because they're more concentrated in the wine.
Of course, without processing technology, consumers would be missing out on many important nutrients. Witness the myriad benefits being attributed to soy.
"No one can consume a raw soybean," notes Janet Pang, R&D manager at Vitasoy U.S.A. "We have to process it in order to make it consumable."
Still, the food designer faces the challenge of making a product consumable, indeed palatable, while retaining as much nutritive value as possible. In the case of soy foods, for instance, the isoflavones that are apparently responsible for so many health benefits also cause the "beany" flavor that may be undesirable in certain products.
Alcohol extraction is more effective in getting rid of the flavor than water extraction, but it also gets rid of the isoflavones, explains Ed Coco, Ph.D., executive vice president at Protein Technologies International, St. Louis.
By using soy protein isolates instead of concentrates, food designers can retain more of the isoflavone content without the undesirable flavors. Still, roughly 50% of the isoflavone content is lost in the process, according to Coco.
Food designers have been coping with similar issues when it comes to vitamins for some time. To varying degrees, vitamins are degraded by heat, oxygen and moisture. Water-soluble vitamins are most susceptible, vitamin C in particular.
Some of these losses can be minimized or prevented by the creative use of ingredient and processing technology. For example, suppliers have been working with encapsulation technology using different types of coating materials to improve stability. One result is that today, even baked products can be fortified with vitamin C.
Many beverage processors have been turning to ultra-high-temperature (UHT) or high-temperature/short-time (HTST) pasteurization to minimize the loss of vitamins and other nutrients. Al Bolles, Ph.D., Tropicana Products' vice president of research and technical services, stresses that immediate cooling and cold-filling play key roles, as well.
To prevent oxidation of the vitamins, Tropicana also deaerates the lines, literally vacuuming the dissolved oxygen at specific points. The company's patented Dual Lock packaging helps reduce oxygen permeation into the carton, further protecting vitamin C.
As interest in phytochemicals continues to grow, food designers will need an equally clear understanding of how these chemicals are affected by processing technology. Researchers at the Brassica Chemoprotection Laboratory at Johns Hopkins University School of Medicine, Baltimore, expect to provide some answers shortly.
Paul Talalay, M.D., and other scientists there have been researching the cancer-fighting compounds in broccoli and other cruciferous vegetables for several years. Much of their work has focused on sulforaphane.
The American Institute of Cancer Research has awarded Talalay's program a grant specifically to study the effects of thermal processing on the anti-carcinogenic compounds in these vegetables. The researchers are studying more than 100 compounds and expect to publish some results in late spring or early summer.