First international conference on East-West perspectives on functional foods: Singapore, September 1995 – Conferences, Symposia, and Reports
All foods provide essential nutrients to maintain bodily health, but functional foods, by virtue of physiologically active components, are purported to be effective in preventing or treating disease and promoting optimal health. Worldwide acceptance of these foods is growing among consumers, food technologists, the food and pharmaceutical industries, and governments concerned with rising health care costs, said Mr. Goh Chee Wee, Singapore’s Minister of State for Trade and Industry and Communications, who gave the keynote address at the conference. His remarks, along with many of the findings presented at the meeting, piqued the interest of the local media, which gave the conference significant coverage.
Although Japan has taken the lead in developing a market for these foods–also called nutraceuticals and designer foods–there is a longstanding tradition elsewhere in Asia of attributing healing properties to certain foods and herbs, Mr. Goh said. Laboratory and epidemiologic investigations are attempting to ascertain the scientific basis for the efficacy of these traditional “cures and medicines,” but have “only touched the tip of the iceberg.”
“As consumers worldwide become more affluent and health conscious, demand for health-enhancing foods is sure to grow,” Mr. Goh said. But to realize the full market potential of these foods, consumers must be assured of their efficacy and safety, he said, adding that “only science can dispel some of the myths shrouding some of these traditional functional foods.” It is also critical to establish internationally acceptable standards and regulations to protect consumers from “bogus products,” Mr. Goh said. “This conference is a good start.”
TRADITIONAL REMEDIES, MODERN EVIDENCE
Describing a tradition that dates from about 1000 B.C., Dr. Chen Junshi of the Chinese Academy of Preventive Medicine said that food and medicine are of equal importance in Chinese medicine. For example, the use of pork liver to treat night blindness and of congee made from rice husk or brown rice to treat and prevent beri beri is cited in medical works from 1400 years ago, during the Tang Dynasty. Even earlier–340 A.D., during the Jin Dynasty–marine algae were prescribed to prevent and treat goiter, and pork pancreas was recommended in the treatment of diabetes, Dr. Chen said.
Eastern folklore and tradition have long recognized tea, and especially green tea, as a healthful beverage, according to Mr. Ivor E. Dreosti of Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO). Recently, several human epidemiologic studies and laboratory animal studies world-wide point to the potential health benefits from antioxidant and other compounds found in green and black teas that may play a role in the prevention of such degenerative diseases as cancer, cardiovascular disease, and ocular cataracts, he said.
Scientists from Sarawak University in Malaysia collected specimens of leaves, roots, stem, bark, flowers, and fruit from some 300 plants used in traditional medicine formulations in rain forest communities in Malaysia and screened them for antitumor activity. The in vitro tests found that five extracts were cytotoxic to a cell line of acute human lymphoblastic leukemia, said the university’s Dr. Rahmad Mohamed.
The medical use of turmeric, a common spice in Indian diets sometimes called the “salt of the Orient,” dates back to ancient times, said Mrs. Kamala Krishnaswamy of India’s National Institute of Nutrition. It is known to have antiseptic and vermicidal properties, and its active component, curcumin, has received much attention in recent times as an anti-inflammatory agent. Animal experiments found that turmeric in the diet is a potent antimutagen against several carcinogens. Turmeric and curcumin inhibited both the initiation and the promotion of tumors in the skin, breast, oral cavity, and forestomach in several rodent species, she said.
A variety of ginseng, Panax ginseng, says C. A. Meyer, has long been regarded as a life-prolonging tonic in the Orient. Dr. Taik-Koo Yun of the Korea Cancer Center Hospital, Seaoul, reported on his study of the anticarcinogenic effects of ginseng against various chemical carcinogens. Pulmonary adenomas that developed in newborn mice given injections of carcinogenic compounds were inhibited after they were fed red ginseng extract. An epidemiologic study he undertook in humans found an association between ginseng consumption and reduced rates of various cancers, including lip, oral cavity and pharynx, esophagus, stomach, and colon and rectum. His trend analysis found that the correlation was greater with increasing ginseng consumption.
The disease-preventing potential of dietary estrogens, or phytoestrogens, found in flaxseed and soy proteins was reviewed by Dr. Kenneth D. R. Setchell of Children’s Hospital Medical Center, Cincinnati. Studies undertaken by his research group in the 1980s found that modest intakes of either flaxseed or soy proteins resulted in markedly increased blood and urine levels of two classes of estrogenic compounds, the lignans and the isoflavonoids, in normal adults. Dr. Setchell and his coworkers hypothesized that the presence of these bioactive nutrients in the diet would be beneficial in the prevention and treatment of certain hormone-dependent diseases, including breast cancer and cardiovascular diseases. Subsequent studies supported this hypothesis, including the demonstration that isoflavones provide anticancer actions in several animal models of carcinogenesis and in vitro against human cancer cells lines. These studies, he said, also support observations that daily intake of soy protein will cause significant modifications to the hormonal regulation of the menstrual cycle of premenopausal women, modifications considered beneficial with regard to risk factors for breast cancer.
The medicinal properties of garlic, noted since ancient times, were reviewed by Dr. John A. Milner of Pennsylvania State University. Epidemiologic studies demonstrate a correlation between greater garlic intakes and reduced cancer risk, a relationship observed worldwide, and laboratory studies have found that garlic and related compounds inhibited tumors in a variety of animal models and in vitro systems, he said. Protection against chemically induced cancer has been observed in such tissues as liver, colon, esophagus, lung, and breast. Deodorized commercial preparations are as effective as fresh garlic in blocking chemically induced tumors, he said, noting that the presence of both allyl and sulfur seems to be necessary for maximum tumor inhibition.
Although cranberry juice and its cocktail have for many years been widely recommended as a simple way to reduce or treat urinary tract infections in women, the scientific basis for the recommendation until recently was lacking, said Dr. L. N. Kuszminski of Ocean Spray Cranberries, Inc. A large, well-controlled human study conducted by the Harvard Medical School and Brigham and Women’s Hospital in Boston recently found that the consumption of cranberry juice cocktail reduced urinary bacteria and pus by 50% in a group of elderly women subjects compared with controls. Although the scientific validity of traditional treatments has often been dismissed, experimental approaches like this may serve as a model for the validation of a possible functional food relationship, he said.
Among other functional foods and compounds reviewed by scientists at the meeting were mushrooms, tempeh, marine and vegetable oils, a strain of lactobacillus, complex carbohydrates and resistant starch, oligosaccharides, and the antioxidant micronutrients vitamin C, vitamin E, and beta-carotene.
PROOF OF EFFICACY
“It is crucial to agree on the causal relationship that we wish to establish between food and disease,” said Dr. Fergus M. Clydesdale of the University of Massachusetts, Amherst. “The question at hand is, What kind of science is necessary to provide a scientifically valid claim for such a relationship?” Dr. Clydesdale offered some guidelines, including the following.
To establish a convincing scientific relationship between food and health or risk reduction, data from any or all of several sources must be used, including epidemiologic data, clinical studies, and mechanistic data from chemical, cellular, and animal models.
Both developers and regulators must remember that food has characteristics that may make the establishment of a disease relationship difficult. Foods are often complex chemical and physical entities where the physiologically active ingredients are not present in a pure form and the physiologic effect may be due to the synergy between several compounds. Thus, in the interpretation of clinical trials, it must be recognized that the addition of a food or food component to the diet may not be interpretable as a single controlled intervention because of the complexity of food systems. Also, the introduction of a food or a macro component of food may create other dietary changes, physiologic reactions, or changes in eating behavior that blur the interpretation of the effects of the component. Effects must also have time for metabolic stabilization.
“As daunting as some of this may seem, I am convinced that sufficiently consistent and powerful data can be obtained so that consumers become aware of the benefits of functional foods in a way that ensures trust in science, regulators, and the industry producing the product,” Dr. Clydesdale concluded.
Several regulatory issues sur-round the development, marketing, and consumer acceptance of functional foods, and regulators everywhere are dealing with them in a variety of ways.
Japan appears to have taken the lead by issuing licensing criteria to regulate “foods for specified health use.” To receive a license for such a food, said Prof. Kohei Kojima of Azabu University, the applicant must submit documents to an expert committee which demonstrate that certain criteria are met. These include the expectation that improvement in “dietary life” and the maintenance and enhancement of health will occur, establishment of an appropriate consumption level based on medical or nutritional knowledge, thorough definition of the physicochemical properties and methods of qualitative and quantitative determination, assurances that the product is in the form of ordinary food and will be consumed in ordinary dietary patterns rather than only occasionally, documentation that the health benefit of the food or relevant components has a medical and/or nutritional basis and is safe, and assurances that the food and relevant components will not be used exclusively as medical drugs. As of August 1995, 35 products were licensed as “foods for specified health use,” Dr. Kojima said.
Regulatory issues are impeding the development of functional foods in the United States, said Dr. Clare M. Hasler, director of the Functional Foods for Health Program at the University of Illinois, Urbana. Because these foods are at the “food-drug interface,” the government is unsure how to regulate them and the food industry is unclear about what legal claims they can make for them. Further confusion results from the spectrum of definitions used to describe functional foods, she said, although the US National Academy of Sciences’ Institute of Medicine defines them as those that “encompass potentially healthful products [including] any modified food or food ingredient that may provide a health benefit beyond the traditional nutrients it contains.” However they are defined, “functional foods are unquestionably the wave of the future,” Dr. Hasler concluded.
Within the European Union, the situation regarding these foods differs from one member state to another, said Dr. Gerard Pascal of the European Union’s Scientific Committee for Food. But some of the common issues being addressed include the definition of functional foods, agreement that these foods should not systematically refer to diseases and should not claim to cure or treat a disease, the need to identify and understand interactions between specific dietary components and particular biochemical and physiologic functions related to health, and other factors. The European Union, he noted, is providing financial support for research projects that aim to increase knowledge of the effects of functional food constituents–such as dietary fibers, probiotics, and prebiotics–on the microbial flora and the intestinal function.
On the supranational front, the Codex Alimentarius Commission has begun work on guidelines for the use of health and nutrition claims, “the type of claims which are made for functional foods,” said Dr. John A. Race of the Norwegian Food Control Authority. The foods will be subject to international regulation on the basis of the World Trade Organization’s Agreement on the Application of Sanitary and Phytosanitary Measures and the WTO’s Agreement on Technical Barriers to Trade, both of which use Codex standards, guidelines, and other recommendations as international reference points.
The functionality of foods must be based on a sound scientific evaluation of the effects claimed, which will require the same degree of scientific rigor used in maintaining food safety protection, Dr. Race said. Assurances must also be made that claims for functional foods will not lead to misuse or overuse of the food or to the disruption of a sound dietary pattern for individuals and populations. “This First International Conference on East-west Perspectives on Functional Foods will help in providing an understanding which will allow Codex to establish a mechanism for setting priorities for the evaluation and assessment of some of the issues mentioned above,” he said, adding that “it will help show the way forward.”
Four major recommendations emerged from the panel discussion that concluded the meeting. First, functional foods should be described as foods that improve or affect body functions over and above their normal nutritional values. Medical claims should not be made for these foods, and their altered functional effects must be substantiated and scientifically proven through laboratory and human studies. Second, the development of relevant and good biologic markers for body functions should be encouraged. Third, more research using epidemiologic studies should be conducted to evaluate functional foods and their components. And fourth, a functional but not a health or medical claim should be permitted for well-documented and well-studied functional foods.
Publication of the conference proceedings as a supplement to Nutrition Reviews is under consideration.
RELATED ARTICLE: USAID OFFERS DOCUMENTATION ON HNCRSP
The US Agency for International Development has made available on CD-ROM the documentation and findings from The Human Nutrition Collaborative Research Support Program (NCRSP). This study encompasses over 10 years of research on the effects of marginal food intake on the physiologic and behavioral performance of children, women, and households in the developing countries of Mexico, Egypt, and Kenya. These studies were conducted by US Universities–The University of Connecticut, Purdue University, and the University of California, Berkeley–in collaboration with counterpart developing country institutions to establish the relationship between nutrition and functional aspects of development, rather than a cause and effect focused on the household and target individuals in the household.
These data tapes are made available in hopes that research scientists will capitalize on the available data to study the many questions on the relationship of marginal food intake on the many human functions and performance which information on the tapes will make possible. For further information, contact Dr. Samuel G. Kahn, Senior Nutrition and Health Advisor, Office of Health and Nutrition, Bureau of Global Programs Field Support and Research, USAID, 320 21st Street NW, Washington, DC 20523.
(*) Reprinted from ILSI News, Vol. 13, No. 5, September/October 1995, with permission from the International Life Sciences Institute, Washington, DC.
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