Tonic water and is used mostly for its flavor. As a result of the lower quinine content, it is less bitter, and is also usually sweetened, often with high-fructose corn syrup or sugar. Some manufacturers also produce diet (or slimline) tonic water, which may contain artificial sweeteners such as aspartame. Traditional-style tonic water with little more than quinine and carbonated water is less common but may be preferred by those who desire the bitter flavor. In the United States, the US Food and Drug Administration (FDA) limits the quinine content in tonic water to 83 ppm (83 mg per liter if calculated
Human genetic resistance to malaria only gene conferring innate resistance to falciparum malaria; there could be many such genes exerting more modest effects that are challenging to detect by GWA because of the low levels of linkage disequilibrium in African populations. However the same GWA association in two populations is powerful evidence that the single gene conferring strongest innate resistance to "falciparum" malaria is that encoding HbS. The fitnesses of different genotypes in an African region where there is intense malarial selection were estimated by Anthony Allison in 1954. In the Baamba population living in the Semliki Forest region in Western Uganda the sickle-cell heterozygote