Being new to reef keeping and zoa's, I've been doing quite a bit of reading on the various subjects. I found the vitamin c debate interesting and found the following posted at
www.planetzoa.com, it is just over one month old.
Vitamin C and Zoas October 01 2013
Our customers often ask us where we stand on this issue, and we have always responded with an overwhelming word of caution. To briefly summarize for those unfamiliar with the concept, vitamin C (ascorbic acid) bound to a buffering agent (calcium or sodium) is added to the reef aquarium as a supplement for the purpose of promoting zoa health. Proponents have claimed reduced oxidative stress, resulting in enhanced immunity and overall vitality in polyps. The claims, though anecdotal, are not entirely without merit. Buffered ascorbate is a relatively benign substance to reef inhabitants, and further still can become a carbon food source for denitrifying bacteria. Which raises the question and first major criticism, that these anecdotal success stories are simply a result of the polyps reacting to improved water quality. Furthermore, ascorbate as a carbon source is inferior to other proven substances and presents unique challenges in dose calculation. A challenge that I can verify in my own experimentation. However, there is still the purported benefit of antioxidant capacity. Thus far my research has turned up not one study to prove integration of free form vitamin c into the reef organism. I've also yet to find any study regarding endogenous antioxidant levels, and whether zoanthids seek supplementation exogenously. Until a study is unearthed or a new study performed, we advise to err on the side of caution, and rely on scientifically justified means of achieving total polyp nirvana.
Interesting side note, humans, guinea pigs, and a few primates lack L-gulonolactone oxidase, rendering them incapable of producing vitamin C endogenously (internally). The entire rest of the animal kingdom possess this important genetic capability. The USDA recommends an adult 2 lb guinea pig be supplemented with 25 mg per day of vitamin C. The US RDA of the vitamin for adult humans to be 75-90 mg. That's about 1-2 percent of what's recommended for a guinea pig (adjusted for weight). Fortunately, humans have the ability to convert the oxidized form, DHAA, out of the cells and back into vitamin C in times of deficiency. A debate still rages on about how much dietary vitamin C is actually necessary. Curiously, DHAA crosses the blood brain barrier where it converts to vitamin C and performs its restorative magic as it easily crosses cell membranes. Maybe coral would more readily accept DHAA!! Hmm...I wonder if any reef supplements compliment this? Many land vegetables contain ascorbic acid oxidase, and enzyme which rapidly converts AA into DHAA. And though I havent found evidence for it, I suspect nori and spirulina sport this enzyme as well.
