Carotenoids Day Two

Read about Day One here .

Today's sunshine in Boston was a welcomed follow-up to yesterday rains, and the coloring of the day two program at the New Developments in Carotenoid Research with additional carotenoids was an equally welcomed follow-up to yesterday's focus on beta-carotene and vitamin A. Well, today's keynote presentation was on vitamin A/retinoic acid in immune health, but the rest of the day featured lycopene, lutein and zeaxanthin, including research on prostate cancer and eye health.

Catherine Ross, Ph.D., professor of nutrition at Penn State University, detailed how retinoic acid can regulate innate and adaptive immunity in the gut, help maintain intestinal homeostasis, modulate the activities of T helper cells and differentiate T-cells. Calling the nutrient “inflammodulatory,” Ross also explained retinoic acid's effect on various cytokines, including TGF-beta. She further discussed exploration and findings of genomic approaches to retinoid metabolism and immune function.

However, the concentration of the program today focused on the metabolism and activities of lycopene and the tandem of lutein and zeaxanthin. On lycopene's biological function, Xiang-Dong Wang, Ph.D., MD, senior scientist and director of the Nutrition and Cancer Biology Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRC) at Tufts University, home to the carotenoid conference, reviewed the opposing findings of low-dose and high-dose lycopene studies, showing low-dose can provide various benefits, while high-dose can increase inflammation. Saying not much info is compiled on lycopene metabolism, Wang noted the supremacy of tomato products over isolate lycopene, in terms of health benefits research, and suggested other components of tomatoes could be contributing factors. He suggested future research look at the bioactivity of lycopene metabolites, dose-related effects, organ-specific effects and interaction with the oxidative environment, especially in populations of smokers and high-alcohol intake.

Yoav Sharoni, Ph.D., professor in the department of clinical biochemistry at Ben Gurion University, Beer-Sheva, Israel, has been researching the association of tomato carotenoids and reduced incidence of various cancers by focusing on the lycopene's molecular mechanism in cancer. His work looks specifically at induction of phase II enzymes and inhibition of inflammation-related transcription, centered on nuclear factor kappa B (NfkB). He said carotenoid derivatives can inhibit this transcription system, activation of which increases cancer cell proliferation and tumor metastasis while decreasing apoptosis. Further, he noted carotenoid oxidation products, not intact carotenoids, are likely responsible for stimulating the antioxidant response element transcription system, which contributes to cancer prevention. Interestingly, these two mechanisms can also benefit bone health, according to Sharoni.

Steve Clinton, Ph.D., MD, professor of internal medicine at The Ohio State University, capped the program's lycopene segment by sharpening the spotlight on lycopene's effect in the prostate, which contains lycopene. Among the highlights for me, he said blood levels of lycopene appeared to change dramatically and in a short period of time depending on the dietary source (tomato juice, soup, sauce, etc.), and while population and lab studies on lycopene and cancer have helped hone hypotheses and supporting evidence, no causal relationship has been found, which shows the need for more large, multi-institutional studies involving relevant biomarkers.

Rounding out the day and the entire program were a few session on lutein and zeaxanthin, including uptake and biological functions, their role in improving visual performance, and effects on cognitive function. Of note to me, the yellow filters rule at absorbing scattered light in the retina, according to Bill Hammond, Ph.D., professor and director of the graduate program in the brain and behavior program at the University of Georgia, Athens. These filters, lutein-zeaxanthin, help the eye recover faster from photostress (think blinding light during driving) by as much as 5 to 6 seconds. He further noted the increase in macular pigment is associated with an increased tolerance for photostress/glare.

And finally, Elizabeth Johnson, Ph.D., said, “Not all xanthophylls are alike,” referring to the effects of carotenoids on cognitive performance. Among the interesting facts she relayed, results from her research, what stood out to me was that macular pigment status correlates to brain status of lutein and zeaxanthin; serum status of these carotenoids correlates to brain status; lutein is by far the dominant carotenoid in the brain; and, the kicker, increased lutein in the brain correlates to decreased cognitive impairment. In fact, She noted low lutein in the brain is linked to decreased performance.

Overall, while some of the details presented at this conference were technical and complex, including some genomic-heavy sections, it was very educational for a nutrition editor to learn about the latest research directions in carotenoid science. Having so many experts in various areas of carotenoid health and research is a luxury not easily afforded. Thankfully Tufts USDA HNRC and major sponsor DSM worked together to pull it all off. And I might be ready to start a master's in biochemistry/nutrition. Just kidding.