Global Concerns with B Vitamin Statuses: Biofortification, Fortification, Hidden Hunger, Interactions, and Toxicity.

The prevalence of undernutrition due to insufficient energy intake has been reduced by nearly 50% since 1990. This reduction is largely attributed to improved yields of staple crops, such as wheat, rice, and maize; however, these improvements did little for micronutrient deficiencies that affect an estimated two billion people worldwide. Starchy staple crops are energy dense but are often lacking in one or more B vitamins, making resource-constrained people who consume monotonous diets comprised predominantly of these staples at risk for developing deficiency. B vitamin deficiencies occur due to a poor overall nondiversified diet and rarely occur alone. Many B vitamins are essential cofactors involved in the metabolism of other nutrients, including other B vitamins, whereby the deficiency of one B vitamin affects the metabolism and status measurements of another. Food fortification efforts have nearly eradicated diseases of extreme B vitamin deficiency, such as beriberi from thiamin deficiency and pellagra from niacin deficiency. However, subclinical deficiency, sometimes referred to as hidden hunger, is still common especially in low-income countries. Most dietary B vitamins, due to their water-soluble nature, are not a concern for excessive intakes, but synthetic forms used for fortification and supplements sometimes can have adverse effects when consumed in high amounts. Biofortified crops offer a long-term sustainable method to increase the amount of dietary B vitamins for people who rely on staple crops for most of their caloric intake. Efforts have been made to improve B vitamin content of crops, especially for thiamin, vitamin B6 , and folate, but none have undergone human feeding trials; therefore, more research is needed to provide sustainable and scalable solutions in many parts of the world.