Competitive Absorption

      When I speak on the topic of carotenoids I emphasize two factors, specificity if action and competitive absorption. Specificity of action refers to the fact that different members of the carotenoid family have specific modes of action and benefits which can not be accomplished by other carotenoids. For example, "Lutein appears to have an affinity for the peripheral retina and rods, while zeaxanthin seems to be preferentially taken up by the cones of the macula. This means that in order to derive the most complete benefit from carotenoids they need to be consumed as a family rather than in isolation.
     Competitive absorption means that high levels on one carotenoid can depress levels of others reducing the overall benefits of carotenoid intake. This was illustrated in a recent study in which supplementation with large amounts of individual carotenoids was shown to depress levels of other carotenoids. The researchers wrote, "...the dietary intake of large amounts of any one of the three carotenoids depressed the concentrations of the other carotenoids in plasma and most tissues. The high lutein supplement decreased levels of zeaxanthin; the high zeaxanthin supplement decreased lutein levels; and the high beta-carotene supplement decreased levels of both lutein and zeaxanthin. In the face of these dietary perturbations, the retinal content of lutein and zeaxanthin varied considerably."
     The reality of specificity of action and competitive absorption underscores the benefit of supplementation with the NeoLife Carotenoid Complex. It supplies the entire family of carotenoids as found in whole foods while most other products provide only isolated carotenoids most popular in the media at the moment.
     I learned the importance of competitive absorption with regard to Vitamin E many years ago in a conversation with Stephan Christen. Christen, a researcher at U.C. Berkley found that supplementation with only alpha tocopherol depressed levels of gamma tocopherol his laboratory animals. This impaired their ability to detoxify certain carcinogens.
     The NeoLife product philosophy is to provide complexes of nutrients as they are found in nature. This prevents the induction of deficiencies by lop-sided supplementation.
References:
Lutein and Zeaxanthin, Alternative Medicine Review, 2005; 10(2), 128.
Wang, Yingming, et al., Competitive inhibition of carotenoid transport and tissue concentratios by high dose supplements of lutein, zeaxanthin and beta-carotene, Eur J Nutr, 2010; 49:334.