ARS | Publication request: Spirulina is an effective dietary source of zeaxanthin to humans

Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 3, 2011
Publication Date: August 1, 2012
Citation: Yu, B., Wang, J., Suter, P.M., Russell, R.M., Grusak, M.A., Wang, Y., Wang, Z., Yin, S., Tang, G. 2012. Spirulina is an effective dietary source of zeaxanthin to humans. British Journal of Nutrition. 108(4):611-619.

Interpretive Summary: Zeaxanthin is a yellow pigment found in certain foods such as yellow corn, green leafy vegetables, and egg yolks. It is a compound with properties that make it important for eye health. In particular, its presence in human eyes may reduce the risk of cataracts and age-related macular degeneration, both of which lead to poor sight in the elderly. To assess the ability of different foods to provide dietary zeaxanthin, we developed methods to study zeaxanthin absorption in humans. We used spirulina (a microscopic algae) as the experimental food, because it contains zeaxanthin. Spirulina is currently grown commercially and is sold as a good source of protein. We grew spirulina with a special form of water that allowed us to safely tag the zeaxanthin molecules in the food. After feeding this food to human subjects, we collected and analyzed blood samples to look for the tagged zeaxanthin. We learned that spirulina was readily digested and could serve as a rich source of zeaxanthin for humans.

Technical Abstract: Zeaxanthin is a predominant xanthophyll in human eyes and may reduce the risk of cataracts and age-related macular degeneration. Spirulina is an algal food that contains a high concentration of zeaxanthin. In order to determine zeaxanthin bioavailability of spirulina for dietary supplementation in humans, spirulina was grown in nutrient solution with 2H2O for carotenoid labeling. Single servings of 2H labeled spirulina (4.0 - 5.0 g) containing 2.6 - 3.7 mg of zeaxanthin were consumed by 14 healthy male volunteers (4 Americans and 10 Chinese) with 12 g dietary fat. Blood samples were collected over 45 days. Serum concentrations of total zeaxanthin were measured using high-performance liquid chromatography (HPLC), and enrichment of labeled zeaxanthin was determined using liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS). The results showed that intrinsically labeled spirulina zeaxanthin in the circulation was detected at levels as low as 10% of total zeaxanthin for up to 45 days after intake of the algae. A single dose of spirulina can increase mean serum zeaxanthin concentration in humans from 0.06 to 0.15 umol/L in American and Chinese volunteers. The average 15-day area under the serum zeaxanthin response curve to the single dose of spirulina was 293 nmoles-day/umole (range: 254-335) in the American subjects, and 197 nmoles-day/umole (range: 154-285) in the Chinese subjects. It is concluded that the relative bioavailability of spirulina zeaxanthin can be studied with high sensitivity and specificity using 2H labeling and LC-APCI-MS methodology. Spirulina can serve as a rich source of dietary zeaxanthin which can effectively increase serum zeaxanthin concentration in humans.