On a Slow Monday, is the Solution More Lutein and Zeaxanthin?
To be honest, I don’t know what to make of the study by Thomson and colleagues reporting that increases in plasma lutein concentrations may positively affect physical activity and reduce sedentary behavior. Correlations do not infer causality. I would have dismissed the paper but it was a randomized, controlled trial. Forty-four older adults (68.8y) were randomized to receive 21 mg lutein or placebo with 250 mL of full-cream milk per day for 4 weeks. It should also be noted that these individuals had very low lutein and zeaxanthin serum levels (14.5 µg/dL) even after supplementation. [See discussion below].
It is not surprising that previous studies have correlated serum levels of carotenoids, lutein and zeaxanthin, with higher levels of physical activity. After all, lifestyle factors (exercise, sun exposure, smoking, alcohol consumption) and demographic characteristics (age, sex, education, race/ethnicity) are significantly associated with dietary lutein and zeaxanthin intake. Higher blood carotenoid levels are a marker of eating more fruit and vegetables and healthy living. Indeed, a 10% increase in dietary lutein and zeaxanthin intake was associated with a 2.4% increase in serum lutein concentration. Schleicher and colleagues reported that education and income, estimate by the Poverty Income Ratio (PIR), have a significant impact on serum carotenoid levels, as does smoking.
Gruber and colleagues found lower serum lutein and zeaxanthin concentrations were significantly associated with smoking, heavy drinking, not being physically active, higher percentage of fat mass, higher waist-to-hip ratio, and other lifestyle-related factors. Many factors other than diet affect serum carotenoid status. They reported quintiles of serum lutein + zeaxanthin ranging from Q1 with 0.02-0.25 to Q5 with 0.58-4.45 µmol/L (Or 1-14 and 33-253 µg/dL, respectively, using NHANES conversion factor of 0.01758 to convert from µmol/L to µg/dL).
Because of inadequate intake of lutein and zeaxanthin, serum concentrations can be very low. With supplementation, Thomson and colleagues failed to increase serum lutein and zeaxanthin outside the lowest quintile reported by Gruber and colleagues. Low serum carotenoid concentrations are associated with low macular pigment optical density. Lutein and zeaxanthin are important nutrients for the eye and the brain. No doubt that many people could benefit from increasing their lutein and zeaxanthin status.
Is there enough evidence to suggest lutein and zeaxanthin supplementation might increase physical activity and reduce sedentary behavior? It is an intriguing hypothesis that suboptimal lutein and zeaxanthin concentrations could be associated with sedentary activity and/or desire to be physically active. It is a question worthy of further examination, keeping in mind that nutrients are not magical.
Nutrient inadequacy can impair cellular function. However, pharmacologic intakes do not confer supraphysiologic powers.
Thomson RL, Coates AM, Howe PRC, Bryan J, Matsumoto M, Buckley JD. Increases in plasma lutein through supplementation are correlated with increases in physical activity and reductions in sedentary time in older adults. 2014 Nutrients doi:10.3390/nu6030974
Rock CL, Thornquist MD, Neuhouse ML, Kristal AR, Newmark-Sztainer D, Cooper DA, Patterson RE, Cheskin LJ. 2002 J Nutr 132:525S-530S
Schleicher RL, Sternberg MR, Pfeiffer CM. Race-ethnicity is a strong correlate of circulating fat-soluble nutrient concentrations in a representative sample of the US population. 2013 J Nutr doi:10.3945/jn.112.172965
Gruber M, Chappell R, Millen A, LaRowe T, Moeller SM, Iannaccone A, Kritchevsky SB, Mares J. Correlates of serum lutein + zeaxanthin: findings from the Third National Health and Nutrition Examination Survey. 2004 J Nutr 134:2387-2394
Curran-Celentano J, Hammond Jr BR, Ciulla TA, Cooper DA, Pratt LM, Danis RB. Relation between dietary intake, serum concentrations, and retinal concentrations of lutein and zeaxanthin in a Midwest population. 2001 Am J Clin Nutr 74:796-802