Efficacy of Weekly Versus Daily Folic Acid Supplementation

460 women of a rural community in the western highlands of Guatemala were recruited for participation in the double-blinded study led by Emory University and the Institute of Nutrition of Central America and Panama (INCAP). The women were randomly assigned one of 4 vitamin treatments containing different levels of folic acid, Vitamin B12, iron and zinc. The treatments were as follows:

• weekly dose of folic acid at 5000ug, iron at 120 mg, zinc at 30mg, and B12 at 16.8 ug;
• weekly dose of folic acid at 2800ug, iron at 120mg, zinc at 0mg and B12 at 16.8ug;
• daily dose of folic acid at 400ug, iron at 60mg, zinc at 15mg, B12 at 2.4ug; and
• daily dose of folic acid at 200ug, iron at 50mg, zinc at 0mg, and B12 at 2.4ug.

The women, aged 15-49, received the vitamins daily for 3 months. Anthropometric data and blood samples were taken at baseline and post-supplementation. The participants also completed a series of dietary interviews at baseline and post-intervention. No pregnant or lactating mothers were admitted into the study, nor severely anemic females. Blood samples were sent to the National Laboratory in Cuernavaca, Mexico, for analysis of serum folate levels.

Inclusion criteria

• female
• aged 15-49

Exclusion criteria

• pregnant
• lactating less than 3 months
• severely anemic