UNIVERSITY OF CALIFORNIA
COOPERATIVE EXTENSION

NUTRITION PERSPECTIVES

Volume 27, No. 1
January/February 2002

TABLE OF CONTENTS PAGE

Folic Acid Fortification for Preventing Neural Tube Defects
Folic Acid Reminder
Alternative Medicine Is No Fad
Herb-Laden Foods Draw FDA Warning
Garlic Supplements can Impede HIV Medication
Tips for the Savvy Supplement User: Making Informed Decisions and Evaluating Information
Tips for Effective Nutrition Screening of the Elderly
Taming Obesity: How Important Is the "Snack Factor"?
The Role of Genomics In Public Health and Disease Prevention
An Endnote on Fruit and Vegetable Intake

Resources:

References that May Help Users Understand and Evaluate Information Encountered on the Internet or In the Marketplace.
New Reference Book May Help Prevent Herb-Drug Mishaps

Subscription for NUTRITION PERSPECTIVES

Sheri Zidenberg-Cherr, PhD, Editor
Department of Nutrition
University of California
Davis, CA 95616

NUTRITION PERSPECTIVES is prepared by Sheri Zidenberg-Cherr, PhD, Nutrition Specialist, Cristy Hathaway, and staff. It is designed to provide research-based information on ongoing nutrition and food-related programs. It is published bimonthly (six times annually) as a service of the University of California Cooperative Extension and the United States Department of Agriculture. Subscription to NUTRITION PERSPECTIVES is available from UC Cooperative Extension, Department of Nutrition, University of California, Davis, California. Cost is ten dollars ($10.00) for a one-year subscription. Subscriptions and questions or comments on articles may be addressed to: NUTRITION PERSPECTIVES, Department of Nutrition, University of California, Davis, CA 95616-5270. Phone (530) 752-3387; FAX, (530) 752-8905.

FOLIC ACID FORTIFICATION FOR PREVENTING NEURAL TUBE DEFECTS

Neural tube defects (NTDs) are among the most common birth defects worldwide, resulting in nerve damage or death of the fetus due to spina bifida and anencephaly. Researchers have long known that folic acid supplementation of pregnant women can help reduce the incidence of NTDs, perhaps by as much as 50 to 70 percent, but translating this knowledge into effective public health policy has been problematic.

To prevent the first occurrence of a NTD, the US Institute of Medicine recommends that women capable of becoming pregnant consume an extra 400 µg/d of synthetic folate, in addition to usual folate intake from foods. This approach recognizes that NTDs occur very early in a pregnancy, about the fourth week post-conception, and that women planning to become pregnant need extra folate at this very critical juncture. However, because an estimated 50 percent of pregnancies are not planned, and unplanned pregnancies usually have not been confirm-ed by the fourth week of gestation, in many cases a NTD will already have occurred by the time the pregnant woman thinks to begin folic acid supplementation (1). Therefore, pregnancy cannot be used as a trigger to initiate supplementation.

Focus on Fortification

The solution to this problem, according to many experts, is population-wide folic acid supplementation through food fortification. In 1998, the US Food and Drug Administration endorsed this view by mandating folic acid fortification of all enriched grain products at a level of 140 µg per 100 g of product. This quantity is not sufficient to produce the full 400 µg/d of supplementation that is recommended for pregnant women, but this reduced level of fortification was deliberately chosen to prevent over-consumption by those who eat large quantities of fortified products. Of particular concern is that widespread fortification could mask pernicious anemia in the elderly, thereby delaying treatment of vitamin B12 deficiency.

Although it is understandable that the FDA would want to err on the conservative side, there has been some question as to whether fortification at these levels will help prevent NTDs. A national panel form the UK recently recommended that flour be fortified with folic acid at 240 µg per 100 g of product, nearly twice the level now mandated in the United States (2). It concluded that fortification at these levels could produce a significant reduction in NTDs without resulting in over-consumption by any population.

References:
1. McKinley MC, McNulty H, McPartlin J, Strain JJ, Pentieva K, Ward M, Weir DG, Scott JM. Low-dose vitamin B-6 effectively lowers fasting plasma homocysteine in healthy elderly persons who are folate and riboflavin replete. Am J Clin Nutr. 2001 Apr;73(4):759-64.
2. Kirby RS. Fortification of foods with folic acid. N Engl J Med. 2000 Sep 28;343(13):971; discussion 972.

Source: Nutrition and the MD; 27(8); August 2001; p. 4.

FOLIC ACID REMINDER

Many physicians are missing a key opportunity to prevent birth defects by not telling their female patients to take a daily multivitamin containing folic acid, says the March of Dimes.

The voluntary health agency made its comments following the September 5 release of a survey of 2001 women aged 18 to 45 conducted by the Gallup Organization under a grant from the Centers for Disease Control and Prevention.

In the survey, 76% of the women said their physicians did not discuss the benefits of folic acid to prevent neural tube defects. Fewer than one third of US women of childbearing age, not pregnant, take a daily multivitamin containing folic acid. But 20% of women asked said that they would be more likely to do so if a physician or other health care professional said to.

The March of Dimes recommends that all women capable of becoming pregnant should take a multivitamin containing 400 µg of folic acid daily beginning before conception and continuing into the early months of pregnancy.

Copies of the survey, "Folic Acid and the Prevention of Birth Defects: A National Survey of Pre-Pregnancy Awareness and Behavior Among Women of Childbearing Age, 1995-2001," item 31-1596-01, may be obtained by calling (800) 367-6630.

Source: JAMA; September 26, 2001; 286(12); p. 1443.

ALTERNATIVE MEDICINE IS NO FAD

Complementary and alternative medicine (CAM) is not a passing fad and will be around for the foreseeable future, said Harvard Medical School researchers in a study published in the August 21 Annals of Internal Medicine.

The study used data compiled from more than 2000 interviews and examined trends in the use of 20 different types of CAM from acupuncture to yoga.
The use of alternative treatments was independent of gender, ethnicity, and education level. Regional trends and urban vs rural differences were also absent. The researchers said most of the 20 therapies have steadily increased in popularity since the 1960s, with the largest overall growth rate occurring in the late 1960s and early 1970s.

The researchers noted the timing of societal adoption of particular therapies. In the 1960s, commercial diet programs, lifestyle diet therapy, megavitamin therapy, and self-help groups increased markedly. The 1970s saw growth in biofeedback, energy healing, herbal medicine, and imagery. In the 1980s, massage and naturopathy increased while yoga decreased in popularity. The 1990s brought increased use of aromatherapy, energy healing, herbal medicine, massage, and yoga.

Source: JAMA; September 26, 2001; 286(12); p. 1443.

HERB-LADEN FOODS DRAW FDA WARNING

Despite concerns about the safety and efficacy of some herbal supplements, since the Dietary Supplement Health and Education Act went into effect the FDA has generally not taken aggressive action against the marketing of supplements or, more recently, foods containing herbal supplements. Now, however, the growing trend toward adding herbs to conventional foods has prompted the agency to act.

In letters to three beverage manufacturers, the FDA warned the companies that their products might be illegal because of additives, which include Echinacea, Siberian ginseng, and Gingko biloba, that are not generally recognized as safe (GRAS) (1). Under regulatory law, food products differ from stand-alone supplements in that any additives must be approved ahead of time or be proven safe through scientific testing before they can be sold. In its letters, the FDA has requested data showing that the products are safe; if such evidence is not provided, the agency can order them off the market.

The smaller companies who received the letter are hardly the only enterprises that are marketing foods with herbal additives. Conglomerates PepsiCo and Cadbury Schweppes both market Echinacea-containing drinks via their SoBe and Snapple lines of beverages. Other herbal products, such as St. John's wort and kava, are showing up in snack crackers and chips. Receipts from herb-containing foods and beverages accounted for just $20 million in sales in 1997; they have ballooned to some $700 million in 2000.

The quality of herbal additives contained in most foods is unlikely to produce a biological effect in most people. But, as described elsewhere in table 1, some additives may have an adverse impact on those taking medications, especially anticoagulants, or those about to undergo surgery.

So, the bottom line is that foods containing herbal ingredients that are not GRAS make little sense for anyone except the companies that market them. Individuals who are serious about obtaining the therapeutic benefits of herbs will find that herb-containing foods may be poor sources of most active ingredients. Conversely, susceptible individuals may be at risk for adverse reactions.

The following table provides a list of therapies and proposed mechanisms for weight loss.

Reference:
1. [Online source] www.fda.gov/foi/warning_letters/g1317d.pdf.

Adapted from: Nutrition & the MD; 27(10); September 2001; pp. 6-8.

GARLIC SUPPLEMENTS CAN IMPEDE HIV MEDICATION

Researchers have found that garlic supplements can cause a potentially harmful side effect when combined with a type of medication used to treat HIV/AIDS. Investigators from the National Institutes of Health (NIH) observed that garlic supplements sharply reduced blood levels of the anti-HIV drug saquinavir. The study results appeared in an on-line edition of "Clinical Infectious Diseases" (http://www.journals.uchicago. edu/CID/journal/home.html) (1).

"In the presence of garlic supplements, blood concentrations of saquinavir decreased by about 50 percent among our study participants," explains the study's senior co-author Judith Falloon, MD, an AIDS clinical researcher at the National Institute of Allergy and Infectious Diseases (NIAID). "We saw a definite, prolonged interaction. The clear implication is that doctors and patients should be cautious about using garlic supplements during HIV therapy," she says.

For the first three days of the study, nine healthy, HIV- negative volunteers received doses of saquinavir, one of a class of drugs called protease inhibitors that are effective at slowing the progression of HIV infection. The research team drew samples of the volunteers' blood to measure their baseline levels of saquinavir in the bloodstream.

Next, the volunteers took garlic caplets twice daily for three weeks. When the researchers again analyzed blood samples, the average overall levels of saquinavir had decreased 51 percent, and the average maximum concentrations had fallen 54 percent.

Even after a ten-day "wash-out" period with no garlic supplements, when the volunteers again used only the protease inhibitor for three days, their blood levels of saquinavir still averaged about 35 percent lower than the expected baseline amount.

The research paper's lead author is Stephen C. Piscitelli, Pharm D., formerly with the NIH Clinical Center Pharmacy Department and now the Associate Director of Clinical Pharmacology at Tibotec-Virco. Noting that some dietary supplements can cause detrimental interactions with medications, Dr. Piscitelli and his colleagues set out to investigate the effects of a number of herbal therapies. As Dr. Falloon explains, "We set out to learn more about these alternative medicine products because there simply are not a lot of clinical data available on them." In their first study, the team found a potentially dangerous interaction between the herbal remedy St. John's wort and the protease inhibitor indinavir.

Garlic became the next focus because of its reputation as a natural cholesterol fighter, which has made it particularly popular for patients whose cholesterol levels have risen due to a side effect from HIV medications. The research team also suspected a strong possibility of a drug interaction because both garlic and protease inhibitors share the same pathway in the body, a metabolic route known as the CYP450 enzyme system. Exactly how garlic supplements disrupt the uptake of saquinavir is still unclear.

Other questions remain as well, says Dr. Falloon. Usually, doctors prescribe saquinavir to be taken together with several anti-HIV drugs, and it is unknown how garlic supplements would affect such a combined drug regimen. "More research is needed in this area, but it's clear from this study that any patient using saquinavir as the sole protease inhibitor should avoid using garlic supplements," says Dr. Falloon.

NIAID and the Warren Grant Magnuson Clinical Center are components of NIH. NIAID supports basic and applied research to prevent, diagnose, and treat infectious and immune-mediated illnesses, including HIV/AIDS and other sexually transmitted diseases, tuberculosis, malaria, autoimmune disorders, asthma and allergies. The Clinical Center is the clinical research hospital for NIH. Through clinical research, physicians and scientists translate laboratory discoveries into better treatments, therapies and interventions to improve the nation's health. Press releases, fact sheets and other NIAID-related materials are available on the NIAID Web site at: http://www.niaid.nih.gov.

Reference:
1. Piscitelli, SC, Burstein, AH, et al. "The effect of garlic supplements on the pharmacokinetics of saquinavir." Clin Infect Dis; 2002; 34(2): 234-8.
Source: NIH Press Release; Wednesday, December 5, 2001.

TIPS FOR THE SAVVY SUPPLEMENT USER:
MAKING INFORMED DECISIONS AND EVALUATING INFORMATION

FDA, as well as health professionals and their organizations, receive many inquiries each year from consumers seeking health-related information, especially about dietary supplements. Clearly, people choosing to supplement their diets with herbals, vitamins, minerals, or other substances want to know more about the products they choose so that they can make informed decisions about them. The choice to use a dietary supplement can be a wise decision that provides health benefits.

However, under certain circumstances, these products may be unnecessary for good health or they may even create unexpected risks.

Given the abundance and conflicting nature of information now available about dietary supplements, you may need help to sort the reliable information from the questionable. Below are tips and resources that we hope will help you be a savvy dietary supplement user. The principles underlying these tips are similar to those principles a savvy consumer would use for any product.

Basic Points to Consider

Do I need to think about my total diet?

Yes. Dietary supplements are intended to supplement the diets of some people, but not to replace the balance of the variety of foods important to a healthy diet. While you need enough nutrients, too much of some nutrients can cause problems. You can find information on the functions and potential benefits of vitamins and minerals, as well as upper safe limits for nutrients at the National Academy of Sciences Web site at: http://www.iom.edu/iom/iomhome.nsf/Pages/FNB+Reports .

Should I check with my doctor or healthcare provider before using a supplement?

This is a good idea, especially for certain population groups. Dietary supplements may not be risk-free under certain circumstances. If you are pregnant, nursing a baby, or have a chronic medical condition, such as, diabetes, hypertension or heart disease, be sure to consult your doctor or pharmacist before purchasing or taking any supplement. While vitamin and mineral supplements are widely used and generally considered safe for children, you may wish to check with your doctor or pharmacist before giving these or any other dietary supplements to your child. If you plan to use a dietary supplement in place of drugs or in combination with any drug, tell your health care provider first. Many supplements contain active ingredients that have strong biological effects and their safety is not always assured in all users. If you have certain health conditions and take these products, you may be placing yourself at risk.

Some supplements may interact with prescription and over-the-counter medicines.

Taking a combination of supplements or using these products together with medications (whether prescription or OTC drugs) could under certain circumstances produce adverse effects, some of which could be life-threatening. Be alert to advisories about these products, whether taken alone or in combination. For example: Coumadin (a prescription medicine), ginkgo biloba (an herbal supplement), aspirin (an OTC drug) and vitamin E (a vitamin supplement) can each thin the blood, and taking any of these products together can increase the potential for internal bleeding. Combining St. John's Wort with certain HIV drugs significantly reduces their effectiveness. St. John's Wort may also reduce the effectiveness of prescription drugs for heart disease, depression, seizures, certain cancers or oral contraceptives.
Some supplements can have unwanted effects during surgery:

It is important to fully inform your doctor about the vitamins, minerals, herbals or any other supplements you are taking, especially before elective surgery. You may be asked to stop taking these products at least 2-3 weeks ahead of the procedure to avoid potentially dangerous supplement/drug interactions -- such as changes in heart rate, blood pressure and increased bleeding - that could adversely affect the outcome of your surgery.

Adverse effects from the use of dietary supplements should be reported to MedWatch:

You, your health care provider, or anyone may report a serious adverse event or illness directly to FDA if you believe it is related to the use of any dietary supplement product, by calling FDA at 1-800-FDA-1088, by fax at 1-800-FDA-0178 or reporting on-line at: http://www.fda.gov/medwatch/how.htm. FDA would like to know whenever you think a product caused you a serious problem, even if you are not sure that the product was the cause, and even if you do not visit a doctor or clinic. In addition to communicating with FDA on-line or by phone, you may use the MedWatch form available from the FDA Web site.

Who is responsible for ensuring the safety and efficacy of dietary supplements?

Under the law, manufacturers of dietary supplements are responsible for making sure their products are safe before they go to market. They are also responsible for determining that the claims on their labels are accurate and truthful. Dietary supplement products are not reviewed by the government before they are marketed, but FDA has the responsibility to take action against any unsafe dietary supplement product that reaches the market. If FDA can prove that claims on marketed dietary supplement products are false and misleading, the agency may take action also against products with such claims.

Tips on Searching the Web for Information on Dietary Supplements

When searching on the Web, try using directory sites of respected organizations, rather than doing blind searches with a search engine. Ask yourself the following questions:

· Who operates the site?
Is the site run by the government, a university, or a reputable medical or health-related association (e.g., American Medical Association, American Diabetes Association, American Heart Association, National Institutes of Health, National Academies of Science, or US Food and Drug Administration)? Is the information written or reviewed by qualified health professionals, experts in the field, academia, government or the medical community?

· What is the purpose of the site?
Is the purpose of the site to objectively educate the public or just to sell a product? Be aware of practitioners or organizations whose main interest is in marketing products, either directly or through sites with which they are linked. Commercial sites should clearly distinguish scientific information from advertisements. Most nonprofit and government sites contain no advertising; and access to the site and materials offered are usually free.

· What is the source of the information and does it have any references?
Has the study been reviewed by recognized scientific experts and published in reputable peer-reviewed scientific journals, like the New England Journal of Medicine? Does the information say "some studies show…" or does it state where the study is listed so that you can check the authenticity of the references? For example, can the study be found in the National Library of Medicine's database of literature citations (PubMed link - http://www.ncbi.nlm.nih.gov/PubMed/)

· Is the information current?
Check the date when the material was posted or updated. Often new research or other findings are not reflected in old material, e.g., side effects or interactions with other products or new evidence that might have changed earlier thinking. Ideally, health and medical sites should be updated frequently.

· How reliable is the Internet or e-mail solicitations?
While the Internet is a rich source of health information, it is also an easy vehicle for spreading myths, hoaxes and rumors about alleged news, studies, products or findings. To avoid falling prey to such hoaxes, be skeptical and watch out for overly emphatic language with UPPERCASE LETTERS and lots of exclamation points!!!! Beware of such phrases such as: "This is not a hoax" or "Send this to everyone you know."

More Tips and To-Do's

Ask yourself: Does it sound too good to be true?

Do the claims for the product seem exaggerated or unrealistic? Are there simplistic conclusions being drawn from a complex study to sell a product? While the Web can be a valuable source of accurate, reliable information, it also has a wealth of misinformation that may not be obvious. Learn to distinguish hype from evidence-based science. Nonsensical lingo can sound very convincing. Also, be skeptical about anecdotal information from persons who have no formal training in nutrition or botanicals, or from personal testimonials (e.g. from store employees, friends, or online chat rooms and message boards) about incredible benefits or results obtained from using a product. Question these people on their training and knowledge in nutrition or medicine.

Think twice about chasing the latest headline.

Sound health advice is generally based on a body of research, not a single study. Be wary of results claiming a "quick fix" that depart from previous research and scientific beliefs. Keep in mind science does not proceed by dramatic breakthroughs, but by taking many small steps, slowly building towards a consensus. Furthermore, news stories, about the latest scientific study, especially those on TV or radio, are often too brief to include important details that may apply to you or allow you to make an informed decision.

Check your assumptions about the following:

· Questionable Assumption -
"Even if a product may not help me, it at least won't hurt me." It's best not to assume that this will always be true. When consumed in high enough amounts, for a long enough time, or in combination with certain other substances, all chemicals can be toxic, including nutrients, plant components, and other biologically active ingredients.
· Questionable Assumption -
"When I see the term 'natural,' it means that a product is healthful and safe." Consumers can be misled if they assume this term assures wholesomeness, or that these food-like substances necessarily have milder effects, which makes them safer to use than drugs. The term "natural" on labels is not well defined and is sometimes used ambiguously to imply unsubstantiated benefits or safety. For example, many weight-loss products claim to be "natural" or "herbal" but this doesn't necessarily make them safe. Their ingredients may interact with drugs or may be dangerous for people with certain medical conditions.
· Questionable Assumption -
" A product is safe when there is no cautionary information on the product label." Dietary supplement manufacturers may not necessarily include warnings about potential adverse effects on the labels of their products. If consumers want to know about the safety of a specific dietary supplement, they should contact the manufacturer of that brand directly. It is the manufacturer's responsibility to determine that the supplement it produces or distributes is safe and that there is substantiated evidence that the label claims are truthful and not misleading.
· Questionable Assumption -
" A recall of a harmful product guarantees that all such harmful products will be immediately and completely removed from the marketplace." A product recall of a dietary supplement is voluntary and while many manufacturers do their best, a recall does not necessarily remove all harmful products from the marketplace.
Contact the manufacturer for more information about the specific product that you are purchasing.
If you cannot tell whether the product you are purchasing meets the same standards as those used in the research studies you read about, check with the manufacturer or distributor. Ask to speak to someone who can address your questions, some of which may include:
· What information does the firm have to substantiate the claims made for the product? Be aware that sometimes firms supply so-called "proof" of their claims by citing undocumented reports from satisfied consumers, or "internal" graphs and charts that could be mistaken for evidence-based research.
· Does the firm have information to share about tests it has conducted on the safety or efficacy of the ingredients in the product?
· Does the firm have a quality control system in place to determine if the product actually contains what is stated on the label and is free of contaminants?
· Has the firm received any adverse events reports from consumers using their products?

NOTE: You may obtain more information on how FDA regulates dietary supplements and on the manufacturers' responsibilities for the products they market at "Questions and Answers." http://www.cfsan.fda.gov/~dms/ds-faq.html

Source: [Online source] http://www.cfsan.fda.gov/~dms/supplmnt.html; Center for Food Safety & Applied Nutrition; Dietary Supplements; January 2002.

TIPS FOR EFFECTIVE NUTRITION SCREENING OF THE ELDERLY

Appropriate nutrition screening and assessment are pivotal to prevention malnutrition in the elderly, especially among those hospitalized or in long-term institutional care (1). The factors leading to malnutrition in the elderly can be diverse and quite complex, but the evaluation process for identifying at-risk patients need not be overly complicated.

To help maximize accuracy while also making efficient use of resources, a common-sense approach to nutrition screening and assessment is advocated. This practicality is reflected in the answers to the following frequently asked questions.

What should be included in the initial nutrition screen and assessment of the elderly patient?

The following is a brief summary of the most important elements to include in the initial evaluation. Readers are encouraged to seek out more detailed information from the list of additional resources presented later in this article.

· History, including a detailed dietary and medication history. In addition to prescription medication, be sure to ask about use of over-the-counter, herbal, and alternative therapies as well.
· Physical examination, including anthropometrical measurements, assessment of activities of daily living, and cognitive/mental status if indicated.
· Laboratory tests, including CBC, albumin, cholesterol, folic acid, and vitamin B12.

What warning signs should nutrition professionals look for?

While no single parameter should be relied upon to make the diagnosis of malnutrition, the following are commonly used in identifying at-risk individuals:

· Involuntary weight change of 10 percent of body weight in three months;
· Albumin < 3.5 g/dL;
· Total lymphocyte count £ 1500; and
· Low score on the Subjective Global Assessment and/or Patient Generated Subjective Global Assessment.

Elderly patients may not provide accurate information, either because of impaired memory and cognition or because they're afraid or embarrassed to tell the truth. How does the clinician overcome this?

Patience and developing trust are critical when dealing with the elderly, just as with other patients. In many cases it is also important to have a close family member or significant other present during visits, especially for the performance of a history and physical examination. This will help you obtain accurate information regarding nutrition, activity, medication use, and underlying diseases and disabilities, all of which are critical for effective management of elderly patients.

What other nutrition screening resources can you recommend?

There is a great deal of information available in the literature and on the Internet. One resource found to be useful is a self-administered questionnaire called "The DETERMINE Checklist." This is one of three screening tools that were developed by and are readily available from The Nutrition Screening Initiative, 1010 Wisconsin Ave. NW, Suite 800, Washington, DC 20007, (202) 625-1662, email: nsi@gmmb.com; or through the American Academy of Family Physicians' website, www.aafp.org/nsi. There is also a monograph for professionals that discus nutrition and its role in a variety of chronic diseases available at www.aafp.org/nsi/manual.

Reference:
1. Barrocas A. Nutritional support of the hospitalized elderly. Nutrition & the MD; September 2001; 27(9); pp. 1-2.

Source: Nutrition & the MD; September 2001; 27(9); p.4.

TAMING OBESITY: HOW IMPORTANT IS THE "SNACK FACTOR"?

In assessing the reasons for increased obesity in today's children and young adults, some say that decreased physical activity is the primary causative factor. They note that television, videogames, and the web have usurped the role of active recreation among young people, and that this generation of couch potatoes is bound to become overweight.

But, is too much sitting around the only thing that contributes to childhood obesity? Some researchers argue that children's snacking habits also have taken a turn for the worse. For evidence, two recent studies show that today's young people snack more often, with foods that have a higher energy density and a greater percentage of energy from fat, than children of previous decades.

Two Decades of Data

In two separate reports of children 2 to 18 years old and young adults 19 to 29 years old, researchers from the 1977-78 National Food Consumption Survey and the 1989-91 and 1994-96 Continuing Surveys of Food Intake by Individuals. In each of the surveys, "snacking" was self-reported by the participants, and the investigators grouped snack foods that were consumed within 15 minutes of each other as part of the same discrete snack (1,2).

Snacking Prevalence and Frequency

In the years covered by the surveys, the percentage of individuals who snacked increased from 77 percent to 91 percent in children and from 77 percent to 84 percent in young adults.

In what was described by the investigators as "the most significant change in snacking behavior" observed in children, the mean number of snacks eaten per day increased anywhere form 24 percent to 32 percent, depending on the age group. This was about a snack-per-day increase over the 1977 value of 1.6 snacks per day. In young adults, snacking frequency increased by a smaller amount, 14 percent.

Energy Content

In 1977, snacks contributed about 20 percent of total energy intake in the diets of children; by 1996, this figure had increased to 25 percent of total energy, Likewise, in young adults, the percentage of total energy intake from snacks increased from 20 percent to 23 percent during the study period. In both groups, the energy density of snacks increased significantly, while the energy density of other meals stayed essentially the same.

"Super-sizing" to Blame?

The studies came to different conclusions about the average size (calories) of snacks during the two decades covered by the surveys. Data from the young adults showed that the energy consumed per snack increased by 26 percent during the study period, suggesting that snack portions had become larger.
According to investigators, this fits with a popular belief that "super-sizing" is a trend with tangible impacts on nutritional intake. By contrast, the data in children showed that energy consumed per snack had remained approximately the same, and that more frequent snacking, not larger snack portions, were largely to blame for increased overall snack energy intake in this group.

Potential Positives

These results suggest that more healthful snacking behavior could make a significant contribution to lowering energy intake in young people. The consumption of smaller, more frequent meals (considered snacking by some) may have important health benefits. In very young children, between-meal snacks can be beneficial because a child's stomach is quite small. In adults, research suggests that eating smaller, more frequent meals may have a positive influence by increasing satiety and lowering overall energy intake. Although much remains to be studied about meal frequency and its impact on body composition, clinicians can help patients and their children adopt beneficial, as opposed to problematic, snacking habits (3) by suggesting that they:

· Eat snacks between meals only when hungry.
· Choose healthy snack foods with a low energy density, such as vegetables, fruits, whole grains, and beans (calcium rich foods such as yogurt are also good choices for children).
· Reduce the "empty" calories of salty, high-fat snacks and sugary beverages.

References:
1. Jahns L, Siega-Riz AM, Popkin BM. The increasing prevalence of snacking among US children from 1977 to 1996. Journal of Pediatrics 2001;138:493-498.
2. Zizza C, Siega-Riz AM, Popkin BM. Significant increase in young adults' snacking between 1977-1978 and 1994-1996 represents a cause for concern! Preventive Medicine 2001;32:303-310.
3. [Online reference]: Kenney J, www.foodandhealth.com/cpecourses/snack.shtml

Source: Nutrition and the MD; 27(12); December 2001; p. 4-5.

THE ROLE OF GENOMICS IN PUBLIC HEALTH AND DISEASE PREVENTION

Francis Collins and colleagues articulated a vision for using genomics in disease prevention in a "hypothetical case in 2010 (1)." In this case, a 23-year-old man named John elects to undergo DNA testing for genes related to several diseases. The results suggest that while John is at lower than average risk for prostate cancer and Alzheimer disease, he is at increased risk for lung and colon cancer, as well as for coronary artery disease. Fortunately, this hypothetical case scenario even remotely possible by 2010 will require a concerted public health effort to translate genomic sequence data into new opportunities for disease prevention.

The Genetics of Common Diseases

Traditionally, genetic diseases have been perceived as rare conditions resulting from high-penetrance mutations inherited in a Mendelian fashion such as Tay-Sachs disease (2). However, the etiology of common chronic diseases such as cancer, heart disease, and diabetes also has a significant genetic component. In these cases, inheritance is non-Mendelinan and complex, making the causal genetic factors difficult to identify. Variants of multiple genes may each contribute a small part of the total risk for an individual. For example, evidence supports a role for common variants of a drug-metabolizing enzyme, N-acetyltransferase, in mediating susceptibility to sporadic bladder and colorectal cancer (3). Because these variants only become risk factors in the presence of bladder or colon carcinogens, they alter an individual's risk only slightly, but they may be responsible for a large number of cancers in populations that are exposed to carcinogens (3).

Currently, because the presence of common genetic polymorphisms alone cannot accurately predict disease susceptibility, genetic tests for these variants rarely furnish information that can be used in prevention. The hope for the future is to learn what combination of gene variants and environmental factors predispose people to disease, and to use this information to prevent disease. For example, people who have the gene variant that codes for the "slow-acetylator" form of N-acetyltranferase, and who have a specific combination of other, as yet unidentified, risk factors, might be counseled to avoid working with bladder carcinogens like aniline dyes. In the future this model may provide targeted intervention and prevention. The US Centers for Disease Control and Prevention (CDC) has detailed the essential public health functions for genetics to play a role in disease prevention (4).

Public Health, Genetics, and Disease Prevention

Population based epidemiological studies are needed to learn the prevalence of gene variants that predispose people to disease, the burden of disease and death caused by these diseases, and the prevalence of disease-causing environmental exposures in genetically susceptible people. These studies are also needed to identify how environmental factors interact with genetic factors to cause disease. Such studies will often take years to complete, although in some cases, the information can be obtained retrospectively using incident case-control studies that are derived from population-based registries of diseases (5).

For genetic tests to have practical value, they must be evaluated for their sensitivity, specificity, and positive predictive values in relation to measured genotypes (analytic validity) and specific health outcomes (clinical validity). To calculate these essential parameters, information about the prevalence and penetrance of disease-associated gene variants is required from population-based studies. When this information is available, genetic tests may improve the clinical predictive values of traditional risk factors for disease. For example, hypercholesterolemia is an independent risk factor for heart disease that can be treated with statin drugs (6).

Because nearly one third of the US population has hypercholesterolemia, an important public health priority would be to optimize the cost-effectiveness of statin therapy. Genetic testing may one day identify the population that will benefit most from these drugs.

As more genetic tests are developed and marketed, it will be important to evaluate the value they add to existing medical and behavioral interventions. Population research will facilitate this evaluation of genetic testing and therapy and thereby prevent its misuse while helping to realize its benefits. Although new developments in genomic medicine will give physicians new tools for promoting health, preventing disease, and managing illness, they will also create a new responsibility to ensure they are used wisely and well.

References:

1. Collins FS, Patrinos A, Jordan E, et al. New goals for the US Human Genome Project: 1998-2003. Science; 1998l 282:6829.
2. Myerowitz R. Tay-Sachs disease-causing mutations and neutral polymorphisms in the Hex A gene. Hum Mutat. 1997; 9:195-208.
3. Hein DW, Doll MA, Fretland AJ, et al. Molecular genetics and epidemiology fo the NAT1 and NAT2 acetylation polymorphisms. Cancer Epidemiol Biomarkers Prev; 2000; 9:29-42.
4. Khoury MJ. Genetic epidemiology and the future of disease prevention and public health. Epidemiol Rev; 1997; 19:175-180.
5. Yang Q, Khoury MJ, Coughlin SS, Sun F, Flanders WD. On the use of population-based registries in the clinical validation of genetic tests for disease susceptibility. Genet Med; 2000; 2:186-92.
6. Jacobson TA. Clinical context: current concepts of coronary heart disease management. Am J Med. 2001;110 (Suppl 6A): 3S-11S.

Source: JAMA; October 3, 2001; 286(13); p. 1635.

AN ENDNOTE ON FRUIT AND VEGETABLE INTAKE

While dietary intake of fruits and vegetables is associated with reduced risk of many different disease states including certain types of cancer and atherosclerosis, the mechanism of the protective effect is not fully elucidated and may relate to macronutrient substitution, trace nutrients, or phytochemicals.

An interesting report by Blacklock and colleagues (1), offers a new hypothesis of interest. These authors measured blood salicylic acid concentration in subjects taking low does of aspirin and non-aspirin-taking omnivores and vegetarians (Buddhist monks) in Scotland. They found highly variable, but detectable, blood salicylic acid levels in all subjects tested, and much higher average levels in the aspirin takers than the non-aspirin takers.

The authors note that while salicylic acid does not have the anticoagulant properties of aspirin, even low plasma levels, in the range observed in many of these subjects, is sufficient to inhibit the COX-2 prostaglandin inflammation pathway, which is inhibited by some of the new anti-inflammatory drugs, some of which are also being explored for use in certain malignancies such as colon cancer.

Whatever the mechanism of the health-protective effects of fruits and vegetables, "five a day" continues to be good advice.

Reference:
1. Blacklock CJ, Lawrence JR, Wiles D, Malcolm EA, Gibson IH, Kelly CJ, Paterson JR. Salicylic acid in the serum of subjects not taking aspirin. Comparison of salicylic acid concentrations in the serum of vegetarians, non-vegetarians, and patients taking low dose aspirin. J Clin Pathol. 2001 July; 54(7):553-5.

Source: Nutrition and the MD; 27(8); August 2001; p. 8.

RESOURCES:

REFERENCES THAT MAY HELP USERS UNDERSTAND AND EVALUATE INFORMATION ENCOUNTERED ON THE INTERNET OR IN THE MARKETPLACE.

Evaluating Research

10 Things to Know About Evaluating Medical Resources on the Web A short guide developed by the National Cancer Institute, NIH, to help you evaluate medical Web sites. (July 1999). cancertrials.nci.nih.gov/beyond/evaluating.html

How to Understand and Interpret Food and Health-Related Scientific Studies
This article provides an overview for understanding and interpreting food and health-related scientific studies (from the International Food Information Council, May 2000). www.ific.org/proactive/newsroom/release.vtml?id=17953

Making Sense of Health and Nutrition News

Provides tips for evaluating science.(IFIC, Food Insight. Jan/Feb 2001
www.ific.org/proactive/newsroom/release.vtml?id=19403

Navigating the Internet

Medical products and the Internet. A guide to finding reliable information.
This document provides advice from the World Health Organization to help internet users obtain reliable, independent, and comparable information on the internet.
www.who.int/medicines/library/qsm/who-edm-qsm-99-4/medicines-on-internet-guide.html

"Navigating for Health: Finding Accurate Information on the Internet".
(IFIC Food Insight article, November-December, 2000)
www.ific.org/proactive/newsroom/release.vtml?id=18846

Health Information On-line

This article provides tips and links for finding information on the web as well as advice to help you determine the reliability of different web sites.
www.cfsan.fda.gov/~dms/fdonline.html

Quality of Health Information.
Several links to other government and private sector web sites compiled by the Department of Health and Human Services' Healthfinder web site to help you evaluate online health information.
www.healthfinder.gov/scripts/SearchContext.asp?topic=14310&section=5

Product Claims and Labeling
"Claims That Can Be Made for Conventional Foods and Dietary Supplements"
An FDA explanation of the various kinds of claims that can be made for foods and supplements. (Updated April 2001.)
www.cfsan.fda.gov/~dms/hclaims.html

"Staking a Claim to Good Health".
Reviews the health claims that FDA has authorized for use on food labels. (FDA Consumer article, November - December 1998.)
www.cfsan.fda.gov/~dms/fdhclm.html

FDA Dietary Supplement Questions and Answers.
Provides information about what dietary supplements are, and how they are regulated, including the labeling and claims that can be made for supplements.
www.cfsan.fda.gov/~dms/ds-faq.html

Questions You Can Ask About Health Claims.
"Improving Public Understanding: Guidelines for Communicating Emerging Science on Nutrition, Food Safety and Health."
These questions were developed to help journalists and scientists accurately convey health information. You can ask yourself these questions to help judge whether the information you are reading is fairly presented (the International Food Information Council, 1998)
www.ific.org/proactive/newsroom/release.vtml?id=17560

"Miracle" Health Claims: Add a Dose of Skepticism
This FDA/FTC joint agency information piece focuses on how to assess claims and seek advice, and avoid becoming a victim of health fraud. The information discusses how to minimize being cheated out of money, time, and health. (September 2001)
www.ftc.gov/bcp/conline/pubs/health/frdheal.htm

The Story of the Laws Behind the Labels.
This article on the history of food and drug laws provides useful insights on the regulation of health claims over the years. (FDA Consumer, June 1981.)
www.cfsan.fda.gov/~lrd/history1.html

Advertising Dietary Supplements
"Dietary Supplements: An Advertising Guide for Industry".
This document describes the factors that FTC takes into account in deciding whether an ad is truthful and not misleading. You can use them to judge the advertisements you see.
www.ftc.gov/bcp/conline/pubs/buspubs/dietsupp.htm

"Promotions for Kids' Dietary Supplements Leaves Sour Taste"
(FTC article, May 2000)
www.ftc.gov/bcp/conline/features/kidsupp.htm

Other Sources

MedWatch.
FDA Safety Information and Adverse Event Reporting Program www.fda.gov/medwatch/safety.htm

The Food and Nutrition Board
The Food and Nutrition Board (FNB), National Academy of Sciences, as part of its mission, establishes principles and guidelines of adequate dietary intake. The FNB issues reports such as "Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline."
www.iom.edu/iom/iomhome.nsf/Pages/FNB+Reports

NUTRITION.GOV
NUTRITION.GOV, a new federal resource, provides easy access to all online federal government information on nutrition, including dietary supplements.
www.nutrition.gov/framesets/frameset.php3?topic=food facts&subtopic=dietary supplements

MEDLINE Plus Health Information: Vitamin and Mineral Supplements
MEDLINE Plus Health Information is a service of the National Library of Medicine, National Institutes of Health, that provides information on health topics, including vitamin and mineral supplements. www.nlm.nih.gov/medlineplus/vitaminandmineralsupplements.html

International Bibliographic Information on Dietary Supplements (IBIDS)
The International Bibliographic Information on Dietary Supplements (IBIDS) NIH, Office of Dietary Supplements is a database of published, international, scientific literature on dietary supplements, including vitamins, minerals, and botanicals. ods.od.nih.gov/databases/ibids.html

National Center for Complementary and Alternative Medicine, NIH .
The National Center for Complementary and Alternative Medicine (NCCAM) at the National Institutes of Health (NIH, www.nih.gov) is dedicated to exploring complementary and alternative healing practices in the context of rigorous science; training CAM researchers; and disseminating authoritative information.
nccam.nih.gov
Source: [Online source] http://www.cfsan.fda.gov/~dms/supplmnt.html; Center for Food Safety & Applied Nutrition; Dietary Supplements; January 2002.

NEW REFERENCE BOOK MAY HELP PREVENT HERB-DRUG MISHAPS

Even doctors don't always know which herbs interact with which drugs, leaving herb-takers at serious risk for adverse herb-drug reactions. Enter the Herb-Drug Interaction Handbook (Church Street Books, 2000), a handy reference developed by registered Dietitian Sharon Her. Intended primarily for use by health professionals (the spiral-bound paperback fits in a lab coat pocket), it's full of information detailing possible interactions between more than 350 herbs and dozens of different drugs.

Not surprisingly, the handbook is dense with medical terminology, and the bare-bones format takes a little getting used to. And while one scientific citation listed might say that an herb has no known interactions with drugs, another might say that there are several. That is, the recommendations aren't always flat-footed, and it's sometimes up to the reader to decide whether to err on the side of caution.

But that doesn't mean the book isn't helpful for a layperson choosing to self-medicate with herbs. For example, someone who uses antihistamines to cope with seasonal allergies could find a list of 16 herbs, among them the sleep aid valerian, which might interact with the drugs to cause symptoms like excess drowsiness. And a light sleeper who occasionally takes valerian could consult the handbook to find that he or she could risk over-sedation by combining the herb with (among other things) alcohol or certain anti-depressants.

To order the book, which costs $21.95 (plus $5.00 shipping and handling), write to Food Medication Interactions, P.O. Box 204, Birchrunville, PA 19421-0204. You can also call (800) 746-2324, fax (610) 827-7669, or online at: www.foodmedinteractions.com.

Source: Tufts University, Health & Nutrition Letter; November 2001; 19(9); p.3.

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