What is the Recommended Dietary Allowance (RDA) of vitamin A for adult males over 18 years of age?

The Recommended Dietary Allowance (RDA) for vitamin A for adult males over 18 years is 900 micrograms (ug) per day. This guideline is established to meet the nutritional needs of the majority of individuals in this demographic, ensuring that they receive adequate amounts of this essential nutrient, which plays a critical role in vision, immune function, and skin health.

Vitamin A exists in two primary forms in the diet: preformed vitamin A (retinol) found in animal products and provitamin A carotenoids found in plant-based foods. The RDA serves as a benchmark to help individuals achieve optimal health and prevent deficiencies that can lead to various health issues.

In the context of the other options provided, the 700, 800, and 1000 micrograms values either fall short of or exceed the established RDA for this demographic group. Thus, 900 micrograms is the correct and scientifically supported amount necessary for adult males over 18 years to maintain proper health and prevent deficiencies.