The implicated product was marketed as a dietary supplement, as stated on the label and the Internet, suitable for the “entire family” to provide a balance of nutrients to “maintain energy and sustain health.” The product contained a blend of 16 vitamins, 12 elements with labeled concentrations and 58 “trace elements,” 18 amino acids, 3 essential fatty acids, Spirulina
, coenzyme Q10, and anti-oxidants, suspended in an ionic colloidal liquid. The label instructions directed adults to take 1 capful (1 fl oz [30 mL]) of the supplement daily, or one-half teaspoon (2.5 mL) for each 20 lb (9.07 kg) of body weight daily for children 5 years or older. On the basis of the reported symptom complex and the laboratory test results of the implicated product obtained by the distributor, selenium was suspected to be the source of illness. The product was labeled as containing 200 μg of selenium per fluid ounce (30 mL) in the form of sodium selenite, an inorganic form of selenium. The FDA subsequently tested the product and determined the selenium concentration to be 40 800 μg/1 oz, approximately 200 times the labeled concentration. Chromium was also identified as being elevated at 17 times the labeled concentration of 200 μg/1 oz. This was less than the amount known to cause adverse health effects among either humans or animals.10,11
None of the affected patients reported symptoms typical of chromium toxicity (eg, gastrointestinal hemorrhage, liver dysfunction, renal failure). All other tested ingredients were within the labeled concentrations.
The incriminated lots of 1200 bottles of the product were manufactured in September 2007, and distribution began in January 2008. Product distribution was primarily in the eastern United States, with the highest concentration in the Southeast. This was reflected in the geographic distribution of cases (). The product was recalled in late March 2008.
Distribution of cases of acute selenium poisoning after ingestion of a misformulated dietary supplement
Structured telephone interviews were administered to all persons identified as having consumed the product. Of 227 consumers, 201 (89%) met the case definition for selenium poisoning. The remaining 26 consumers who did not meet the case definition reported no or mild symptoms. Illness onset extended from January 5 through June 11, 2008 (). The median patient age was 54 years (range, 4–92 years) and 121 (60%) were female. One-hundred forty-nine (74%) were white, and 15 (7%) were black. At the time of the initial interview, 118 (59%) of the patients had sought care at private physicians’ offices, clinics, or emergency departments; 83 (41%) had not brought their symptoms to medical attention. One patient was hospitalized; none died.
Epidemic curve by date of onset of illness after consumption of a misformulated dietary supplement. The arrow indicates date of voluntary product recall.
The median period over which patients had consumed the misformulated product was 29 days (range, 1–109 days). Among 156 patients with data available, the median estimated amount of selenium ingested was 989 mg (range, 41–5875 mg), for a median of 41 585 μg/d (range, 3400–244 800 μg/d; recommended dietary allowance, 55 μg/d). Among 98 patients with weight and dose available, the median dose ingested was 12.8 mg/kg (range, 0.5–115.4 mg/kg).
The most frequently reported symptoms included diarrhea (78%), fatigue (72%), hair loss (70%), joint pain (67%), nail discoloration or brittleness (61%), nausea (57%), and headache (45%) (). The proportion of scalp hair lost ranged from 10% to 100%, with a median of 50%. Foul breath (37%) and cutaneous eruption (26%) were also commonly reported.
Reported Symptoms of Selenium Toxicity After Consuming a Misformulated Dietary Supplement
A follow-up questionnaire was administered to 104 of 150 patients (69%) in Florida, Georgia, and Tennessee, at a median of 106 days (range, 43–206 days) after symptom onset. Among patients originally reporting specific symptoms and who were interviewed 90 days or more after symptom onset, symptoms persisting 90 days or more included fingernail discoloration and loss (52%), fatigue (35%), hair loss (29%), joint pain (26%), memory loss (22%), and muscle aches (22%) ().
Persistence of Symptoms 90 Days or More After Cessation of a Misformulated Dietary Supplement
Of the 78 patients reporting hair loss, 14 (18%) reported complete loss of scalp hair. One patient (1%) reported total body hair loss. Of the 74 patients who reported fingernail discoloration or brittleness, 28 (38%) reported nail loss.
Initial serum selenium concentrations were obtained from 8 patients at a median of 1 day after cessation of product consumption (range, 0–33 days). Initial serum selenium concentrations ranged from 321 to 1500 μg/L, with a mean of 761 μg/L and a median of 664 μg/L; 3 were higher than 1000 μg/L (reference mean, 125 μg/L).12
Initial urine specimens from 7 patients were obtained at a median of 9 days after cessation of product consumption (range, 6–37 days). Initial urine selenium concentrations ranged from 55 to 227 μg/d, with a mean of 166 μg/d and a median of 179 μg/d (reference mean for Tennessee residents, 55 μg/d).13
Serum and urine selenium concentrations decreased gradually with time, with values returning to normal by weeks 1 to 2 for urine and starting at week 6 for serum.
The supplement was distributed by Company A, a small privately owned company in Atlanta, Georgia. The product had been on the market for 12 years without any reported problems. Company A received the finished product from a manufacturer in Arkansas, which in turn received ingredients from suppliers in Louisiana.
The FDA conducted inspections of the manufacturing and supply plants after the outbreak was identified. Company A had recently changed the manufacturer of the product, and the misformulated lots were the first lots produced after the change. Employee error at one of the ingredient suppliers was determined to be the cause of the increased selenium in the product.