Final answer:
Folic Acid is the recommended supplement for women of childbearing age to decrease the incidence of neural tube defects in their offspring.
Step-by-step explanation:
The supplement recommended for women of childbearing age to decrease the incidence of neural tube defects such as spina bifida in their offspring is Folic Acid.
Folic acid, also known as vitamin B9, is important for the healthy development of the neural tube. A deficiency of maternal folate during early pregnancy can result in neural tube defects.
Taking a daily dose of at least 400 µg/day of folate from supplements or fortified foods is advised by the Food and Nutrition Board of the Institute of Medicine.