Help may be at hand for those of us who want to keep the wrinkles and grey hair at bay and slow down the process of aging. New research suggests that eating green vegetables can ward off the signs of aging. Researchers say that broccoli, cabbage and avocado in particular contain a compound that helps slow down the rate at which we age. The key compound, present in green fruit and vegetables, is called NMN. It helps slow down the physical signs of getting old. Scientists say NMN can also rejuvenate the metabolism. It helps replenish levels of energy production in our body that deteriorate as we age. It also helps reduce weight gain and the deterioration of vision.