The goal of this protocol is to determine the vitamin A value (equivalence) of spirulina. The investigation will use intrinsically deuterium labeled spirulina and an isotope vitamin A reference dose, 13C10- retinyl acetate (13C10 RAc), in males (n=20). Up to 45 blood samples (10 ml/sample) will be collected from each subject over a two-month period to evaluate the bioavailability and bioconversion of spirulina ß-carotene to vitamin A.

By utilizing novel stable isotope dilution techniques recently developed in our laboratory, we will trace deuterium labeled ß-carotene in intrinsically labeled spirulina, which is harvested from a hydroponic system. In the mean time, we will track 13C10 labeled vitamin A in humans. In this way we will determine absorption of ß-carotene from spirulina matrix and the conversion of the spirulina ß-Carotene to retinol. This will enable us quantitatively determine the vitamin A equivalence of spirulina.

The specific aims of this study are:

1. To determine labeled ß-C blood response kinetics following an acute dose of intrinsically labeled spirulina;
2. To determine labeled retinol blood response from the intrinsically labeled spirulina;
3. To determine 13C10 retinol blood response from the isotope reference material 13C10 retinyl acetate;
4. To determine s spirulina-vitamin A equivalence.

Inclusion Criteria:

• Healthy volunteer

Exclusion Criteria:

• Not has GI track problems
• Any medical condition that will affect the intestinal absorption