When Promoting Fruit Consumption Goes Sour
For many years, the Florida Department of Citrus has produced ads that exaggerate the value of citrus products. The most recent example, appearing both on television and on its Web site, suggests that drinking a single glass of orange juice per day can greatly reduce the odds of having a stroke. According to a press release on its Web site: A study published in the October 6 edition of the Journal of the American
Medical Association (JAMA) found that drinking a glass of orange or
grapefruit juice every day may lower the risk of stroke by 25 percent....
[The researchers] found that increasing overall vegetable consumption
reduced the risk of stroke by just four percent, but increased consumption
of cruciferous vegetables (broccoli, Brussels sprouts, cauliflower, etc.)
cut the risk by 32 percent. As for fruit, increasing overall consumption
lowered stroke risk by 11 percent, but simply drinking a glass of orange
juice every day reduced the risk of stroke by 25 percent.
This study, which was well designed, was supported by grants from the U.S. Office of Dietary Supplements and by the Florida Department of Citrus. The researchers examined data on 75,596 women, ages 34 to 59, who were followed for a 14-year period, and on 38,683 men, ages 40 to 75, who were followed for eight years. All of the participants were free of cardiovascular disease when the studies began. The study found that those with the highest intake of fruits and vegetables--particularly cruciferous vegetables, green leafy vegetables, and citrus fruit and juice--had the lowest incidence of strokes caused by obstruction of blood supply to the brain. The researchers noted, however, that "the analyses of individual fruit and vegetable items did not show any single fruit or vegetable that was strikingly more protective than others" (JAMA 282:1233-1239, 1998).The Citrus Department's "25 percent reduction" figure was derived from a table showing that the people reporting consumption of one serving per day of citrus juice had 20% fewer ischemic strokes than the 20% of people who consumed the fewest number of servings of fruits and vegetables. The study provides strong support for the prevailing scientific recommendation to consume at least five servings of fruits and vegetables a day. But it cannot predict the effect of adding citrus juice to your current diet--as the ad suggests.
In 1986, the department advertised that people who exercised couldn't get enough potassium in their diet and that the potassium in grapefruit juice not only would provide enough, but would "balance sodium levels to regulate blood pressure and fight off fatigue." When the National Advertising Division (NAD) of the Council of Better Business Bureaus investigated, a department spokesperson said that the potassium deficiency claims were based on an opinion survey of athletes conducted by a nutrition consultant, plus a study of the effects of intense conditioning in young men undergoing basic military training. In addition, a literature survey was provided as substantiation of the roles of sodium and potassium as nutritional factors in controlling blood pressure. NAD's investigator replied that the data obtained from the studies could not support broadly stated claims and that the ad had overstated the benefits of drinking normal quantities of grapefruit juice. The spokesperson informed NAD that the claims had been discontinued and that a new campaign would promote grapefruit as a significant source of potassium when part of a healthy regimen, including proper diet and exercise. However, a subsequent ad stated that grapefruit juice was "high in potassium with no sodium: a combination that, along with proper diet and exercise, can help control blood pressure." This was still misleading because drinking normal quantities of grapefruit juice is unlikely to lower blood pressure.
In 1993, the department distributed a booklet containing several pages of misleading information about vitamin C. Among other things, the booklet suggested that vitamin C "may offer remarkable protection against heart disease" and "can help prevent tuberculosis." (The latter claim was attributed to "Dr. Irwin Stone," but did not indicate that Stone's doctoral credential was a Ph.D. from nonaccredited Donsbach University.) The booklet also claimed that vitamin C must be ingested daily because it cannot be stored in the body. This claim was false, because the body normally stores about a month's supply.