Functional Foods and Structure/Function Claims: Is There a Difference Between Sexes?


  Food is critical for human existence. However, food goes beyond nourishment, as it encompasses a multitude of human experiences and emotions, and these vary between cultures and religions. More recently, food is being used and appreciated differently by women and men.


Food is critical for human existence. However, food goes beyond nourishment, as it encompasses a multitude of human experiences and emotions, and these vary between cultures and religions. More recently, food is being used and appreciated differently by women and men.

Differences in health and illness are influenced by individual genetic and physiological makeup, as well as by an individual’s interaction with environmental factors. Identifying sex differences at genetic and molecular levels could explain disease susceptibility, onset, severity, and anticipated response to therapy.

Personalized medicine appears to be the way of the future. However, while concentrating on diagnosing and treating acute and chronic medical conditions, one cannot help considering the importance of prevention. It already has been demonstrated that alteration in lifestyle (e.g., diet and exercise) can influence the onset and severity of disease for a significant percentage of individuals. Therefore, a new wave of consumers is challenging the industry by demanding foods based on their disease-preventive functions. With consumers becoming more health conscious and recognizing the need to take more responsibility to protect their own health, the functional food and drink markets have grown exponentially.


In the 1990s, with the increased public awareness about health and disease prevention, a new category of value-added foods and food ingredient products evolved that is known as functional foods. While the term might be new, the concept dates back 2500 years to Hippocrates: “Let food be thy medicine and medicine be thy food.” According to the National Institutes of Health (NIH; Bethesda, MD), functional foods are defined as “components of the usual diet that may have biologically active components that may provide health benefits beyond basic nutrition.” In the last decade, functional foods became even more appealing to health-conscious consumers with the realization that certain dietary constituents can act synergistically to heighten absorption of nutrients simply through daily food intake (as opposed to supplementation). According to a recent survey, functional foods make up 1% of the food industry, and are growing at the rate of 10% each year to reach projected sales of $70 billion by 2009.

Foods that have added ingredients to produce a health-specific benefit (i.e., functional foods) may now bear so-called structure/function (S/F) claims on the label, provided that these claims are substantiated by scientific data, as required by FDA. While this article primarily focuses on the scientific findings and the possible role that they might play in the functional food arena, it is also important to mention the regulatory aspects under which the industry has to operate. FDA does not have a definition for functional foods and regulates these products as any other food under the Federal Food, Drug, and Cosmetic Act. However, it seems that pressure from consumers and the industry is impacting FDA decisions, as the agency in January allowed S/F claims on conventional foods. S/F claims describe the role of substances intended to affect the normal structure or function in humans, and may not explicitly or implicitly link the relationship to a disease or health-related condition, which is addressed by Qualified Health Claims (21 CFR §101.93). In other words, S/F claims are allowed for a portion of marketed functional foods: those that address only the normal structure or function of the body. These claims can be made without FDA review or authorization before use, but they must be truthful and not misleading, and the claims must derive from the nutritional value of the product.

Increased consumer demand for functional foods is influenced by several factors, not the least of which are the scientific and clinical findings supporting the claims. In an age when the dissemination of scientific findings is made easy by the use of the information superhighway, the public is more informed then ever on the subjects of health, chronic illness, prevention, and nutrition. Scientific advances in these areas, as well as in food technology, allow the food industry to satisfy the increased demand for functional foods by consumers. The traditional “one size fits all” concept has evolved into even-more-challenging product development that currently targets specific demographics, including age, race, and sex. One area of heightened activity is that of functional foods catering to sex-based differences.


Until the 1990s, scientists operated under the long-standing assumption that men and women were biologically the same except for their reproductive organs. However, a major shift occurred within the last decade, as it became evident that more work is needed to address sex differences in nonreproductive areas of biology in the attempt to identify and better define physiological and biological dissimilarities between men and women. There is no doubt that being male or female matters in the prevalence, severity, and age of onset of a broad range of medical conditions. Understanding the foundation of sex-based differences is important in developing new approaches to prevention, diagnosis, and treatment, as well as providing consumers with more disease-prevention value-added food products. Because of the unique physiological makeup and reproductive demands that women encounter throughout life, unparalleled health issues face more than half of the United States population. Research and clinical findings demonstrate that women are affected differently than men by several medical conditions, including:

• Heart disease-Heart disease kills more women than men every year.

• Heart attacks-Women are 11 times more likely to die from a heart attack than from breast cancer.

• Depression-Women are more likely than men to suffer from depression due to lower serotonin synthesis in the brain.

• Stroke-Women suffer less aphasia than men following a stroke, possibly because of the different location of the language centers.

• Autoimmune diseases-Three-fourths of autoimmune diseases (such as lupus and rheumatoid arthritis) occur in women.

• Osteoporosis-For every 10 white women, four by the age of 50 and older will experience a hip, spine, or wrist fracture during the remainder of their lives, as will 13% of white men.1 Both men and women experience an age-related decline in bone mass density starting in midlife. However, the disease presents differently in men than in women, showing a more rapid decline and an earlier age of onset in women.2

Studies have shown that women respond differently than men to certain drugs in terms of effectiveness and are at a greater risk than men for experiencing adverse reactions. While several factors are involved, a key factor remains that women are being underrepresented in drug trials, leading some to suggest that data collected from male-only studies should not be applied to women.3 Finally, because women are often smaller than men, the dose requirement may be substantially different between them. Research has shown that metabolism and rate of metabolism are different for women than men for certain medications, alcohol, and nicotine.

• There is a more rapid clearance in women than men of several drugs, including erythromycin, cyclosporine, verapamil, and diazepam. Rapid clearance might also explain why women react differently to anesthesia.

• Certain drugs (e.g., warfarin) are metabolized differently by women than men, with more serious adverse events noted in women. Women are more likely than men to become addicted to sedatives, antianxiety drugs, or hypnotic agents.4

• Aspirin does not protect women against heart attacks in the same way it does men.

• Women tend to get lung cancer at younger ages than men.

• On average, a smoking woman loses 15 years of her life, while a smoking man loses 13 years.

• Women metabolize nicotine faster than men do, especially women who are taking oral contraceptives.4

• Alcohol has more of an effect on women than on men, because women produce less of the enzyme that breaks down alcohol in the stomach, which may explain why, when consuming equal amounts of alcohol, they have a higher blood-alcohol level than their male counterparts. This may contribute to the finding that women become addicted to alcohol and drugs more easily and the statistic that 6 million girls and women abuse or are addicted to alcohol.4

These examples are just a few of those reflecting the differences in metabolism and rate of metabolism between men and women. These findings, while having relevance in and of themselves, also indicate that similar metabolic pathways likely impact other orally ingested substances, including foods, food ingredients, and dietary supplements. This emphasizes the need for the development of gender-specific products.

When it comes to taste, functional foods face the same challenges as “regular” foods in the eyes of the consumer, which makes product development challenging. It has been suggested previously that food taste preferences vary between sexes. Recently, at the Karolinska Institute (Stockholm) researchers were able to show that these differences exist and that, for example, obese men prefer foods high in fat and protein, while obese women choose foods high in carbohydrate/fat and sugar.5 The findings are significant because they are opening the door for more research in the attempt to elucidate why men and women select and consume different foods.

Age is another important demographic on which the functional food industry has been focusing. It is anticipated that by 2010, a third of all Americans will be 50 or older, while the childbearing group of women is declining at the same time. Recent census information shows that the elderly are a growing population base, with more than 58% of the adults over the age of 65 being female.6 These facts did not escape the food and dietary supplement industry that is already making the 50-and-above age group a priority for product development. The 50-year-old age group is exceptional from a marketing point of view, because baby boomers have more purchasing power than any preceding generation, have a life expectancy of another 36 years, are concerned with their health and motivated to make lifestyle changes to prevent disease onset, and are more loyal to the functional food and dietary supplement industry than any other group, as demonstrated by high levels of regular consumption.

Functional foods represent an area that will likely remain of interest to consumers contemplating life-long, beneficial effects from day-to-day nutrition. Currently, functional foods are being designed for people with special needs and wants, such as adolescents, women of childbearing age, athletes, military personnel, the elderly, and women and men wanting to maintain their youth and health (e.g., beauty foods and cosmeceuticals)-paving the way to individualized nutrition. The selection process for consumers making choices concerning diet and supplements is complex, which should alert industry and regulators to focus on two key areas-the importance of using sound science when substantiating claims (e.g., S/F claims) for functional foods, and educating the public to facilitate the decision-making process. The consumer base is in place, the science is maturing, and the regulatory atmosphere is favorable for quantitative gains in the general public’s health through the use of functional foods.


1. SR Cummings and LJ Melton, “Epidemiology and Outcomes of Osteoporotic Fractures,” The Lancet, 359 (May 18, 2002): 1761–1767.

2. Osteoporosis, Prevention, Diagnosis, and Therapy, National Institutes of Health Consensus Statement, 17, no. 1 (March 27, 2000): 1–45.

3. Canadian Women’s Health Network [online] at

4. Alcohol Problems in Adolescents and Young Adults: Epidemiology, Neurobiology, Prevention, and Treatment, ed. M Galanter. (New York City: Springer-Verlag, 2006).

5. K. Elfhag and S Rossner, “Obesity Patients with Eating Disorders Risk Ending Up Between Medicine and Psychiatry,” Lakartidningen, 104, no. 7 (February 14, 2007): 494–7. In Swedish.

6. 2000 Census Bureau Report.



Ioana G. Carabin, MD, is medical consultant and James Griffiths, PhD, is director of toxicology at the Burdock Group (Vero Beach, FL). For more information about the Burdock Group, visit or call 772/562-3900.


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