MODERN NUTRITION: FADS, FRAUDS, AND QUACKERY
© S. Barrett, 2006
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Food faddism can be defined as an unusual pattern of food behavior enthusiastically adopted by its adherents. It is commonly expressed by (a) beliefs that particular foods or food substances can cure diseases, (b) elimination of certain foods from the diet without adequate reason, and/or (c) emphasis on "natural" foods. Many aspects of food faddism become social movements that represent symbolic rebellions against authority, society at large, or some imagined enemy.
Quackery can be defined as the promotion for profit of a medical scheme or remedy that is unproven or known to be false. This definition seeks to distinguish folk practices and neighborly advice from practices for financial gain. "Health fraud" has been defined in a similar way. However, because most people regard fraud as a deliberate attempt to deceive, the term health fraud is most appropriate when deliberate deception is involved.
Quack methods are sometimes referred to as "alternatives." Because ineffective methods are not true alternatives to effective ones, the terms unscientific or dubious are preferable. "Alternative" methods related to nutrition are discussed in another chapter.
Faddists and quacks urge everyone to distrust large food companies, government regulators, and scientific health professionals. This negative philosophy is essential because without it, there would be no reason to buy health food industry products or consult "alternative" practitioners.
VULNERABILITY TO QUACKERY
Victims of quackery usually have one or more of the following characteristics:
1. They are unsuspecting. Many people believe that if something appears in print or in a broadcast, it must be true or somehow it would not be allowed. People also tend to believe what others tell them about personal experience.
2. They believe in magic. Some people are easily taken in by the promise of an easy solution to their problem. Those who buy one fad diet book after another fall into this category.
3. They are desperate. Many people faced with a serious health problem that doctors cannot solve become desperate enough to try almost anything that arouses hope. Many victims of cancer, arthritis, multiple sclerosis, and acquired immunodeficiency syndrome (AIDS) are vulnerable in this regard.
4. They are alienated. Some people feel deeply antagonistic toward scientific medicine but are attracted to methods that are "natural" or otherwise unorthodox. They may also harbor extreme distrust of the medical profession, the food industry, drug companies, and government agencies.
5. They are overconfident. Despite P. T. Barnum's advice that one should "never try to beat a man at his own game," some strong-willed people believe they are better equipped than scientific researchers and other experts to tell whether a method works.
Nutritional faddism and quackery are promoted with five basic fallacies:
1. Our food supply is nutritionally inadequate because our soils are depleted and important nutrients are removed by food processing. These claims encourage purchase of "organic," "natural," and "health" foods. A typical example is this passage from a book by Earl Mindell, cofounder of the Great Earth chain of health food stores:
"Much of our soil our food is grown in has been depleted of many vitamins and minerals, thanks to the overuse of fertilizers and chemicals. Then the food takes a long time to get to the supermarket. The longer these foods are stored the more vitamins they lose. Many of the foods we eat have been heavily processed, meaning they have been crushed, heated, bleached, extracted, chemicalized and preserved. Then we cook the food, destroying valuable enzymes and what's left of many vitamins. It's a wonder there's any nutrition at all left in our food by the time it gets to our tables!"
2. Vitamin and mineral deficiencies are common. This claim is used to persuade people that everyone should take supplements. A typical example is this passage from Prescription for Nutritional Healing, a book that recommends supplements and/or herbs for more than 250 health problems:
"The problem with most of us is that we do not get what we need from our modern diet. Even if you are not sick, you may not necessarily be healthy. By understanding the principles of wholistic nutrition and knowing what nutrients we need, we can improve the state of our health, stave off disease, and maintain a harmonious balance in the way nature intended."
3. Most health problems are the result of faulty diet and can be treated by "nutritional" methods. These types of claims are used to market food supplements, health foods, and quack dietary methods.
4. US residents are in danger of being poisoned by food additives and pesticide residues. This claim, along with accusations that the food industry and government regulators are untrustworthy, is used to promote the sale of "organic" and "natural" foods.
5. Personal experience is the best way to tell whether a health-related action is effective. This claim encourages people to rely on testimonial evidence rather than scientific studies and prevailing medical beliefs.
Table 1 lists ways to spot nutrition quacks.
Claims for Foods
Many foods are promoted with slogans suggesting that they are safer, more nutritious, or have special therapeutic value. "Organically grown" foods are said to be grown without the use of "artificial" fertilizers or pesticides. The foods themselves are usually indistinguishable from "ordinary" foods but cost significantly more.
US Food and Drug Administration (FDA) market-basket studies indicate that pesticide residues are insignificant in the overall diet. Some studies have found that the pesticide content of "organically grown" and conventionally grown foods is similar. The largest such study measured the levels of more than 300 synthetic pesticides in about a thousand pounds of tomatoes, peaches, green bell peppers, and apples purchased in five cities. Traces were detected in 77% of conventional foods and 25% of organically labeled foods, but only one sample of each exceeded the federal limit. The amounts are small enough that the risk from pesticide is not worth worrying about and does not warrant paying higher prices.
Nutrients are absorbed by the plant in their inorganic chemical state regardless of whether the soil has been prepared with manure, compost, or manufactured fertilizer. Plants grow only if they receive enough nutrients, and their vitamin content is determined by their genes. Fertilizers can influence the mineral composition of plants, but these variations are rarely significant in the overall diet. A study encompassing 460 assessments of nine different fruits and vegetables done in the early 1990s found no significant difference in taste quality between "organic" and conventionally grown samples. Despite such facts, a 1990 federal law forced the US Department of Agriculture to establish standards for organic food "certification." The standards, which took effect in 2002, are embodied in a 26,000-word document that covers definitions, agricultural practices processing, and marketing claims.
The word "natural" is said by its proponents to designate foods that are minimally processed and contain no artificial additives or preservatives. This "no artificial additives or preservatives" is meant to imply that additives and preservatives (MES) pose a health risk. Actually, they help make our food supply safe, abundant, and palatable. Although one is occasionally found to pose a health hazard (e.g., sulfites), the vast majority appear safe, and the overall level in our food supply should not be a cause for concern or a reason to buy "natural" foods. The health food industry also circulates unfounded criticisms of food irradiation, milk pasteurization, and genetically engineered foods.
The term "health food" is commonly used to suggest that certain foods have special health-giving properties not found in "ordinary" foods. Some "health" foods are rich in various nutrients and can be a valuable part of a balanced diet. However, no food has any special health-promoting property beyond those of the nutrients it contains. FDA regulations permit food labels and packages to contain truthful and nonmisleading claims related to (a) calcium and osteoporosis, (b) sodium and high blood pressure, (c) dietary fats and heart disease, (d) dietary fats and cancer, (e) dietary fiber and cancer, (f) fiber and cardiovascular diseases, (g) oatmeal or oat bran and heart disease, (h) soy protein and heart disease, (i) folic acid and neural tube defects, and a few other relationships. The claims must be limited to the relationship between these conditions and a particular food component, rather than the specific product. The recommendation must also be consistent with a sound total diet. Food advertising is primarily regulated by the Federal Trade Commission (FTC), which can apply similar criteria.
Promotion of Supplements
Although some dietary supplements are useful, US residents waste several billion dollars a year on products that are worthless or unnecessary. These products often are promoted with scare tactics and false promises. The most common sales pitch is "nutrition insurance," the idea that everyone needs vitamin and mineral supplements to be sure of getting enough. Some promoters falsely suggest that it is difficult to balance one's diet, whereas others insist that our food supply is inadequate. The best strategy is to have an objective assessment of the quality of one's diet and to modify the diet or use supplementation for any remaining shortfall.
Another common ploy is the suggestion that supplementation is advisable to help deal with "stress." This idea was commercialized by distorting a 1952 National Academy of Sciences report. The report merely stated that people who are seriously ill or injured (some of whom have impaired appetite) might benefit from supplementation to prevent depletion of water-soluble vitamins, which have limited storage. However, in 1976, a major vitamin manufacturer began falsely advertising that "stress robs the body of vitamins" and that water-soluble vitamins must be replaced daily because the body cannot store them. Some manufacturers made no claims for their "stress" products but assumed that consumers would know their purpose. Several manufacturers falsely suggest that being active and elderly creates special needs that their products supposedly meet.
In the mid-1980s, the New York State attorney general secured consent agreements with two major "stress supplement" manufacturers to stop misrepresenting the need for their products. Since that time, the amount of direct advertising of "stress supplements" has greatly decreased. However, the Council for Responsible Nutrition, a trade organization that represents major supplement manufacturers and suppliers, has advertised that a busy lifestyle places US residents at nutritional risk. The advertisement included a narrowly worded "Vitamin Gap Test" suggesting that virtually everyone may have one or more "gaps." Council for Responsible Nutrition representatives maintain that virtually everyone needs supplements. In 1990, the FTC secured a consent agreement barring another large manufacturer from making unsubstantiated claims that any vitamin product is needed to replace nutrients lost as a result of athletic activities or "the stress of daily living." Such "stress" is not a true hypercatabolic state in which increased amounts of calories and nutrients are needed.
Many health food manufacturers market "ergogenic aids" amino acid supplements falsely claimed to increase stamina, endurance, and muscle development. Some of these products are claimed to be "natural steroids" that release growth hormone. No scientific evidence indicates that these products actually release growth hormone, and this is fortunate, because if they did, acromegaly could result. David Lightsey, who coordinates the National Council Against Health Fraud's Task Force on Ergogenic Aids, has requested documentation from more than 80 companies that market "ergogenic aids." Fewer than half sent anything, and the rest submitted studies that were poorly designed or did not actually support product claims. Lightsey also checked statements that various teams were using certain products and found that management had neither endorsed the products nor encouraged their use.
The Federation of American Societies for Experimental Biology (FASEB) has criticized the widespread use of amino acids in supplements. Following extensive review, FASEB experts concluded the following: (a) single- or multiple-ingredient capsules, tablets, and liquid products are used primarily for pharmacologic purposes or enhancement of physiologic functions, rather than for nutritional purposes; (b) little scientific literature exists on most amino acids ingested for these purposes; (c) no scientific rationale has been presented to justify use of amino acid supplements by healthy persons; (d) safety levels for amino acid supplement use have not been established; and (e) a systematic approach to safety testing is needed.
In 2002, the Institute of Medicine's Food and Nutrition Board concluded the following: (a) there is no evidence that amino acids derived from usual or high intakes of protein from foodstuffs present any risk; (b) blood concentrations could be considerably higher when amino acids were consumed as supplements as opposed to a component of protein in food; (c) for some amino acids, studies in healthy persons indicated no evidence of adverse effects; and (d) for other amino acids, the data are insufficient to establish tolerable upper safe intakes. However, when there is a metabolic defect in the utilization of certain amino acids or when renal insufficiency prevents excretion of normal metabolic products of an amino acid, there may be an undesirable effect.
Vitamin C, vitamin E, and β-carotene are being vigorously promoted with claims that their antioxidant properties can help to prevent various diseases by blocking the harmful action of free radicals. Epidemiologic evidence indicates that diets containing significant amounts of fruits, vegetables, and grains are associated with a lower incidence of heart disease and certain cancers. However, it is not known which, if any, specific substances in the diet are responsible or whether taking doses of supplements higher than the recommended dietary allowance (RDA) will do more good than harm. Evidence exists, for example, that vitamin E can help to prevent atherosclerosis by interfering with oxidation of low-density lipoproteins (LDLs). However, vitamin E can also exert an anticoagulant effect. The issue can be settled scientifically by conducting long-term double-blind clinical studies that compare vitamin users and nonusers and measure death rates from all causes.
So far, clinical trials related to the prevention of cardiovascular disease and cancer have not been promising. The US Preventive Services Task Force (USPSTF) concluded the following:
"The available evidence from randomized trials is either inadequate or conflicting, and the influence of confounding variables on observed outcomes in observational studies cannot be determined. As a result, the USPSTF could not determine the balance of benefits and harms of routine use of supplements of vitamins A, C or E; multivitamins with folic acid; or antioxidant combinations for the prevention of cancer or cardiovascular disease.
The USPSTF recommends against the use of beta-carotene supplements, either alone or in combination, for the prevention of cancer or cardiovascular disease."
In addition to marketing antioxidants, many companies are marketing products said to be concentrates of fruits and/or vegetables. Critics note, however, that it is not possible to condense large amounts of produce into a pill without losing fiber, nutrients, and many other phytochemicals. Although some products contain significant amounts of nutrients, these nutrients are readily obtainable at lower cost from foods.
Advice from Retailers
No special knowledge or training is required to become a salesperson at a health food store. Personnel in these stores typically obtain information by reading books and magazines that promote supplements and herbs for treatment of virtually all health problems. Retailers also obtain information from manufacturers and can attend seminars at trade shows sponsored by industry groups and trade magazines. Several large studies have demonstrated that the proprietors of these stores often give advice that is irrational, unsafe, and illegal:
In 1983, investigators from the American Council on Science and Health made 105 inquiries at stores in New York, New Jersey, and Connecticut. Asked about eye symptoms characteristic of glaucoma, 17 of 24 store employees suggested a wide variety of products for a person not seen; none recognized that urgent medical care was needed. Asked over the telephone about sudden, unexplained 15-pound weight loss in 1 month's time, nine of 17 recommended products sold in their store; only seven suggested medical evaluation. Seven of ten stores carried "starch blockers" despite an FDA ban. Nine stores contacted made false claims of effectiveness for bee pollen, and ten stores did so for RNA.
In 1989, volunteers of the Consumer Health Education Council telephoned 41 Houston-area health food stores and asked to speak with the person who provided nutritional advice. The callers explained that they had a brother with AIDS who was seeking an effective alternative against human immunodeficiency virus (HIV). The caller also explained that the brother's wife was still having sex with her husband and wanted to reduce or eliminate her risk of being infected. All 41 retailers offered products they said could benefit the brother's immune system, improve the woman's immunity, and protect her against harm from HIV. Thirty said they sold products that would cure AIDS. None recommended abstinence or using a condom.
In 1993, posing as prospective customers, FDA agents visited local health food stores throughout the United States. The investigators asked, "What do you sell to help high blood pressure?" "Do you have anything to help fight infection or help my immune system?" and/or "Do you have anything that works on cancer?" Of 129 requests for information, 120 resulted in recommendations of specific dietary supplements.
In 1998, a researcher posing as the daughter of a patient with metastatic breast cancer inquired at 40 health food stores in Oahu, Hawaii. After products to assist in metastatic breast cancer care were mentioned and/or shown, if store personnel did not provide any further information, the researcher asked: (a) How does the product work? (b) Do you recommend any particular brand (if more than one brand available)? (c) Could I write down some prices? (d) How much of the product does my mother need to take per day? (e) Can the product(s) be taken together with the medication my mother is receiving from her physician? and (f) Is there anything else you can recommend? Personnel in 36 of the stores recommended one or more of 38 inappropriate products, the most common of which were shark cartilage (recommended by 17) and essiac (recommended by eight), and maitake mushrooms (recommended by seven). Retailers who recommend products when customers describe symptoms violate state laws against the unlicensed practice of medicine or pharmacy, but they are rarely prosecuted.
About 100 companies market supplements through person-to-person (multilevel) sales. Virtually anyone can become a distributor by filling out a one-page application and buying a distributor kit for about $50. Most multilevel companies claim that their products can prevent or cure a wide range of diseases. A few companies merely suggest that people will feel better, look better, or have more energy if they use supplements.
Although pharmacists receive scientific training in nutrition, a study by Consumer Reports has cast considerable doubt on the ability of community pharmacists to give appropriate advice about supplements. When undercover investigators asked 30 pharmacists whether vitamins could relieve their nervousness or fatigue, 17 recommended vitamins, one recommended L-tryptophan, and only nine mentioned seeing a doctor.
Many supplement products are irrationally formulated. Several years ago, two dietitians examined the labels of vitamin products at five pharmacies, three groceries, and three health food stores in New Haven, Connecticut. Products were judged appropriate if they contained between 50 and 200% of the US RDA and no more than 100% of others for which estimated safe and adequate daily dietary intakes exist. Only 16 of 105 (15%) multivitamin-multimineral products met these criteria.
Few supplement products have any usefulness against disease, and most that do (e.g., niacin for cholesterol or triglyceride control and folic acid for lowering abnormal blood levels of homocysteine) should not be taken without competent medical supervision.
Quality Control Problems
Although drugs are subject to rigorous quality control to ensure the nature, potency, and safety of ingredients, dietary supplements and herbs are not. The FDA has proposed adherence to good manufacturing practices but has not taken the necessary steps to require this standard.
ConsumerLab, which has tested hundreds of products since 1999, has reported that about 15% of the vitamins and minerals, 23% of the other supplements, and 38% of the herbals failed their evaluations. The most common reason for the failure was too little or none of the main ingredient. Other problems included the following: too much active ingredient; the wrong ingredient; dangerous or illegal ingredients; contamination with heavy metals, pesticides, or pathogens; "spiking" with unexpected ingredients; poor disintegration (which affects absorption); and misleading product information.
Since the early 1980s, many persons and groups have developed "credentials" intended to resemble those of established medical and nutritional organizations. During this period, unaccredited correspondence schools and other organizations have issued a steady stream of "degrees" and other certificates intended to suggest that the recipient is a qualified expert in nutrition. The schools typically issue B.S., M.S., and/or Ph.D. "degrees" based on study of unscientific writings plus open-book tests that are scored quite liberally. The professional organizations typically grant immediate "professional memberships" and a fancy certificate for a modest fee. Household pets and nonexistent persons have achieved membership in several of these groups. Some organizations offer "certification" based on correspondence courses that invariably include unscientific teachings. The most significant of these is the C.N. (Certified Nutritionist) issued by the nonaccredited National Institute for Nutrition Education.
Such credentials have no legal or scientific standing but can be advertised or displayed in most states that do not regulate nutritionists. The American Dietetic Association is striving for increased regulation of nutritional practice and has gained passage of laws in 41 states.
In 1993, a 32-state survey sponsored by the National Council Against Health Fraud found that 286 (46%) of 618 "Yellow Page" listings under the heading "Nutritionists" were spurious, and 72 (12%) were suspicious. Listings were considered spurious if the advertiser used an invalid method of diagnosis, treatment, or nutritional assessment. Listings were rated suspicious if the practitioner did not comply with a request for information on credentials or methods used. Dubious nutrition practitioners were also found under the headings "Acupuncture," "Health and Diet Products," "Health, Fitness, and Nutrition Consultants," "Herbs," "Holistic Practitioners," "Weight Control Services," and "Wellness Programs." Many such listings were for chiropractors, homeopaths, naturopaths, holistic physicians, health food stores, and multilevel distributors for such companies as Herbalife International, Nu Skin International, Shaklee Corporation, and Sunrider International. The credentials used included C.C.N. (certified clinical nutritionist), C.N. (certified nutritionist), C.C.T. (certified colon therapist), C.M.T. (certified massage therapist), C.N.C. (certified nutrition consultant), H.M.D. (homeopathic medical doctor), L.Ac. (licensed acupuncturist), M.L.D. (manual lymph drainage), N.C. (nutrition counselor), N.D. (doctor of naturopathy), N.M.D. (doctor of nutrimedicine), and O.M.D. (oriental medical doctor). Of 24 persons identified as having a "Ph.D." in their ad, 17 had spurious credentials. Of 231 listings under the heading "Dietitians," 21 (9%) were spurious, including several from GNC stores. The best strategy to avoid entanglement with an unqualified nutritionist is to avoid all practitioners who sell supplements in their offices or espouse the statements listed in Table 1.
DUBIOUS DIAGNOSTIC TESTS
Unscientific practitioners use a variety of tests as a basis for prescribing supplements and/or making dietary recommendations. The most common such test is hair analysis, which is purported to detect "mineral imbalances" or the presence of "toxic minerals." The test is usually obtained by sending a small amount of hair from the nape of the neck to a commercial laboratory for analysis. The laboratory then issues a computerized report suggesting what supplements may be prescribed.
When 52 hair samples from two healthy teenagers were sent under assumed names to 13 commercial hair analysis laboratories, the reported levels of minerals varied considerably between identical samples sent to the same laboratory and from laboratory to laboratory. The laboratories also disagreed about what was "normal" or "usual" for many of the minerals. Literature from most of the laboratories suggested falsely that their reports were useful against a wide variety of diseases and supposed nutrient imbalances. A smaller study published in 2001 yielded similar findings. Properly performed, hair analysis has limited value as a research tool but little if any clinical application.
Supplement purveyors sometimes use "nutrient deficiency tests" to help them decide what their customers need. One type involves completion of a dietary history; another involves completion of a questionnaire about common symptoms that supposedly are signs of deficiency. The answers are then fed into a computer programmed to recommend supplements for everyone. Many such marketers claim that their supplements are individually customized.
Functional intracellular analysis (FIA), formerly called essential metabolics analysis (EMA), is performed by a laboratory that claims that most US residents have nutrient deficiencies and that "intracellular nutrient deficiencies" even occur in more than 40% of US residents who take multivitamins as "insurance." The test is performed by placing lymphocytes from the patient's blood into Petri dishes containing various concentrations of nutrients. A growth stimulant is added, and a few days later, technicians identify the dishes in which "greatest cell growth" takes place, which supposedly points to a deficiency. Properly performed, lymphocyte cultures have a legitimate role in testing for concentrations of certain nutrients, but they are not appropriate for general screening or for diagnosing nutrient deficiencies
Some practitioners use data from legitimate laboratory tests but misrepresent their meaning. Chemistry profiles, which measure many different chemical characteristics of the blood, are a valuable screening test in scientific medical practice. However, dubious practitioners misuse the test by narrowing the normal ranges so healthy persons appear to have abnormalities, which are then used to recommend expensive supplements or special diets.
Some practitioners claim that food allergies may be responsible for virtually any symptom and can be treated with vitamin supplementation plus dietary restriction. To detect the alleged offenders, they assess the levels of various immune responses to foods. These levels, however, are not necessarily related to allergy and have nothing whatsoever to do with a person's need for supplements.
Although thousands of practitioners (mostly chiropractors) use the foregoing procedures, government regulatory agencies rarely attempt to stop them.
QUESTIONABLE DIET PLANS
Many weight-reduction schemes are promoted to the public as a solution to obesity. Fad diet books typically have several things in common. They claim to offer a revolutionary new idea based on the author's personal experience. They suggest that certain nutrients, foods, or food combinations are either the key to weight reduction or the villains that prevent it. In addition, these books contain inaccurate biochemical information. Many fad diets are unbalanced and lack important nutrients.
Since the 1980s, many best-selling diet plans have emphasized proteins, some recommending "unlimited" amounts and others using small amounts. "Food-combining" schemes also have been popular. Fit for Life, which sold more than 3 million copies, claims that obesity caused accumulation of "toxic waste" from incomplete assimilation of foods eaten in the wrong combinations.
The most notorious high-protein (low-carbohydrate) plan has been the Atkins diet, which has four steps: a 2-week "induction" period, during which the goal is to reduce carbohydrate intake to less than 20 g/day; and three periods during which carbohydrate intake is progressively raised but kept below what Atkins calls "your critical carbohydrate level" for losing or maintaining weight. The dieter is permitted to eat unlimited amounts of noncarbohydrate foods "when hungry," but ketosis tends to suppress appetite. The plan calls for checking one's urine for ketone bodies to ensure that the desired level of ketosis is reached. Atkins also recommended large amounts of nutritional supplements.
A computer analysis of sample menus has found that the diet contained 59% fat and provided fewer servings of grains, vegetables, and fruits than recommended by the US dietary guidelines. The investigators also said that although the diet can produce short-term weight loss, long-term use is likely to increase the risk of both cardiovascular disease and cancer. A subsequent literature review found "insufficient evidence to make recommendations for or against the use of low-carbohydrate diets, particularly among participants older than age 50 years, for use longer than 90 days, or for diets of 20 g/d or less of carbohydrates." These reviewers noted that "weight loss while using low-carbohydrate diets was principally associated with decreased caloric intake and increased diet duration but not with reduced carbohydrate content."
A controlled study of 63 people who were randomly assigned to either the Atkins diet or a conventional diet found that the Atkins group lost about 4% more weight for the first 6 months, but there was no significant difference between two groups at 1 year. The low-carbohydrate diet appeared to improve risk factors for heart disease, but the authors concluded that more research is needed on the safety and effectiveness of this regimen.
Low-carbohydrate diets are unsuitable for people with coronary artery disease, gout, or kidney disease. Before a low-carbohydrate diet is started, measurements should be made of the blood levels of creatinine (which reflects kidney function), uric acid (related to gout), and glucose (may detect diabetes, which can elevate triglyceride levels). Low-carbohydrate dieters should also monitor their blood lipid levels and stop the diet if their 3-month total or LDL cholesterol levels rise sharply. Among those whose cholesterol levels improve, the improvement is thought to be related to weight reduction, but no published study has examined the effect of the diet on the coronary arteries.
Because increasing the amount of carbohydrates in a diet can raise triglyceride levels and reduce high-density lipoprotein (HDL), a low-carbohydrate diet may be appropriate for obese persons with abnormally high triglyceride levels. As noted before, it is better to replace carbohydrate with monosaturated or polyunsaturated fat than with protein-fat containing foods, and the diet should contain fewer calories than expended. Future genetic research may be able to determine the diets that are best for persons with metabolic problems based on their genetic pattern.
The recent popularity of low-carbohydrate diets has encouraged food companies to market low-carbohydrate foods for people who want to "watch their carbs." Most of these foods are much higher in fat than the foods they are designed to replace. Thus, "low-carb" advertising is encouraging both dieters and nondieters to eat high-fat foods, which is exactly the opposite of what medical and nutrition authorities have been urging for decades.
QUESTIONABLE "DIET PILLS"
Questionable diet pills are marketed though retail outlets, direct mail solicitations, newspaper advertising, cable television infomercials, and the Internet. Typically, these pills are claimed to produce effortless, rapid, and permanent weight loss. Many are falsely claimed to block absorption of starch, fat, or calories, to flush fat out of the body, or to step up the body's "fat-burning system." Some contain a fiber (e.g., glucomannan or guar gum) that is claimed to curb appetite by absorbing water and swelling to fill the stomach. However, the amount of fiber is too small actually to fill the stomach, and even if it could, that would not necessarily curb a person's appetite. In 1990, guar gum was banned as a diet aid after the FDA received 17 reports of persons whose esophagus became blocked as a result of using tablets of "Cal-Ban 3000," a widely promoted guar gum product.
Spirulina, a dark-green powder or pill derived from algae, is said by its promoters to suppress appetite. However, no scientific evidence supports this claim.
Products containing Gymnema sylvestre are being touted as weight-control aids with claims that they block absorption of sugar. The leaves of this plant, when chewed, can prevent the taste sensation of sweetness. However, no evidence indicates that Gymnema sylvestre blocks absorption of sugar into the body.
Supplements containing chromium picolinate are promoted with unsubstantiated claims that this substance promotes fat loss and increases lean muscle mass. The FTC has stopped some companies from making such claims, but others have continued to do so.
A systematic review of scientific reports, including reviews and metaanalyses, has concluded that chitosan, chromium picolinate, Garcinia cambogia, glucomannan, guar gum, hydroxymethylbutyrate, plantago psyllium, pyruvate, yerba mate, and yohimbe have not been proven effective for reducing body weight. The reviewers stated: "None of the reviewed dietary supplements can be recommended for over-the-counter use."
Products containing ma huang have been marketed as weight-loss aids even though they have not been proven safe or effective for this purpose. Ma huang is an herb that contains ephedrine, a nasal decongestant and nervous system stimulant. Ephedrine can raise blood pressure and therefore is hazardous to persons with high blood pressure. Deaths have been reported among users of stimulants containing ephedrine and caffeine. In April 2004, after concluding that ephedra poses an unreasonable risk of injury, the FDA banned its use as a dietary supplement ingredient.
The FDA is also planning to ban phenylpropanolamine (PPA), which has been used in weight-loss products as well as a nasal decongestant to relieve stuffy nose or sinus congestion. PPA can have a temporary effect on appetite, but no evidence indicates that it offers any long-term benefit for weight control, In 2001, the FDA announced that it plans to ban PPA in all drug products and asked manufacturers voluntarily to stop marketing them. The FDA warning was based on estimates that 200 to 500 strokes per year among persons 18 to 49 years old could be associated with PPA use. A study by scientists at Yale University in New Haven, Connecticut found an association between PPA use and hemorrhagic stroke in women. The study did not contain enough men to estimate the risk to men, but there is no reason to believe it is lower. The FDA's PPA information page provides comprehensive information .
DANGERS OF QUACKERY
Quackery's harm can be classified as economic, indirect, direct, psychologic, and societal. Individual economic damage can range from a few dollars a year for "nutrition insurance" to many thousands of dollars wasted on quack remedies for serious disease. Because everyone must eat, the potential market for nutritional quackery is immense. Indirect harm occurs when the use of an ineffective approach diverts someone from effective care. Direct harm occurs when a dubious method causes death (Fig. 1), serious injury, or unnecessary suffering. Psychologic harm arises when persons blame themselves for the failure of an ineffective remedy or when they mistaken conclude they have been helped and become more vulnerable to future deception. Quackery can also harm our democratic society when large numbers of people hold erroneous beliefs about the nature of disease and the best way to deal with it. Limited resources can be wasted if funds are used to follow leads based on inadequate or faked data.
Between 1986 and 1990, the American Dietetic Association documented more than 500 cases of people harmed by inappropriate nutritional advice from bogus "nutritionists," health food store operators, and others. Privacy considerations, however, prevented the association from publishing a detailed analysis.
The tryptophan tragedy illustrates how inappropriate use of supplements can lead to disaster. In 1989, a form of L-tryptophan was implicated in an outbreak of eosinophilia-myalgia syndrome, a previously rare disorder characterized by severe muscle and joint pain, weakness, swelling of the arms and legs, fever, and rash. This amino acid had been promoted by the health food industry to treat insomnia, depression, premenstrual syndrome, and overweight, although it had not been proven safe and effective for these purposes. Within a year, more than 1500 cases were reported, with 27 deaths and many hospitalizations. When the outbreak's cause was identified, the FDA banned the sale of L-tryptophan products. The outbreak was traced to a Japanese bulk wholesaler that had used a new bacterial strain to produce the L-tryptophan sold to US manufacturers. Attorneys handling the resultant lawsuits state that more than 5000 users were injured, and total damages paid by the errant producer have exceeded $1 billion.