Sunnu Rebecca Choi for NPR Scientists carrying out research on the compound nicotinamide adenine dinucleotide — or simply NAD+ — are running into an unusual problem these days: A little too much publicity around their subject of study. Enthusiasm for NAD+ boosting supplements, injectables and IV infusions has overtaken the wellness and longevity world, attracting A-list celebrities and biohackers — and sparking all manner of claims about its ability to boost energy, combat aging and enhance recovery. "Initially it was exciting," says Christopher Martens , director of the Delaware Center for Cognitive Aging Research who is leading research in this field. "I think now the cart may be well ahead of the horse." In fact, the market for NAD+ products is booming. This optimism has roots in legitimate science. But does the evidence really support dishing out hundreds or thousands of dollars to pump your body full of this molecule? Want the latest stories on the science of healthy living?…