Diets and supplements

Much life extension research focuses on nutrition—diets or supplements—as a means to extend lifespan, although few of these have been systematically tested for significant longevity effects. The many diets promoted by anti-aging advocates are often contradictory. A dietary pattern with some support from scientific research is caloric restriction.^[23][24]

Preliminary studies of caloric restriction on humans using surrogate measurements have provided evidence that caloric restriction may have powerful protective effect against secondary aging in humans. Caloric restriction in humans may reduce the risk of developing Type 2 diabetes and atherosclerosis.^[25] More research is needed.

The free-radical theory of aging suggests that antioxidant supplements, such as Vitamin C, Vitamin E, Q₁₀, lipoic acid, carnosine, and N-acetylcysteine, might extend human life. However, combined evidence from several clinical trials suggest that β-Carotene supplements and high doses of Vitamin E increase mortality rates.^[26] Other substances proposed to extend lifespan include oxytocin, insulin, human chorionic gonadotropin (hCG), and erythropoietin (EPO). Resveratrol is a sirtuin stimulant that appears to extend lifespan in simple organisms such as nematodes^[27] and short-lived fish.^[28]

Some supplements, including the minerals selenium^[29] or zinc^[30][31] have been reported to extend the lifespan of rats and mice, though none have been proven to do so in humans, and significant toxic effects were observed. Metformin^[32] may also extend life span in mice.

There are many traditional herbs purportedly used to extend the health-span, including a Chinese tea called Jiaogulan (Gynostemma pentaphyllum), dubbed "China's Immortality Herb."^[33] Ayurveda, the traditional Indian system of medicine, describes a class of longevity herbs called rasayanas, including Bacopa monnieri, Ocimum sanctum, Curcuma longa, Centella asiatica, Phyllanthus emblica, Withania somnifera and many others. Along with their Chinese counterparts (called superior or tonic herbs), Indian rasayanas demonstrate preliminary positive results in animal models.^[34]