Anti-sickling effect of dietary thiocyanate in prophylactic control of sickle cell anemia.

As a clinical entity, sickle cell anemia (SCA) is known to be relatively rarer in Africans than in the African-American population of the United States. Paradoxically, sickle cell trait (SCT), the non-anemic, heterozygous condition, is about three times more common among indigenous Africans than in African-Americans. The ratio of SCA to SCT is 1:50 for African-Americans, and less than 1:1,000 for tropical Africans. This etiological disparity is attributed to an anti-sickling agent, thiocyanate, (SCN-) found abundantly in staple African foods, such as the African yam (Dioscorea sp) and cassava (Manihot utilissima). Staple American foods have negligible SCN-concentrations. Nonstaple foods in the American diet, such as carrots, cabbage, and radishes, have SCN- levels far below the African yam and cassava. This finding explains the high incidence of SCA among African-Americans and its rarity in Africans.The author concludes that SCA is a congenital deficiency anemia, ameliorable by prophylactic diets of foods with high SCN- contents. Thus, "thiocyanate deficiency anemia" is nutritionally a more correct clinical status for those born with the homozygous sickle hemoglobin genome. Just as any iron undernourished person can suffer from iron deficiency anemia, sickle hemoglobin homozygotes suffer from "thiocyanate deficiency anemia" when they subsist on SCN-deficient foods. This article reviews the role of dietary SCN- in SCA control.