Vitamin C protects the brain and nervous system from damage caused by stress because the synthesis and maintenance of chemical neurotransmitters such as adrenaline and noradrenaline requires adequate levels of vitamin C.  Vitamin C is also needed to repair collagen which is essential for skin, blood vessels, bones and joints, and muscles. When these are damaged by physical stress, extra vitamin C is necessary. A controlled trial of 91 adults who experienced increased anxiety and stress 2-3 months after an earthquake in New Zealand in 2011 was divided into three groups, two were given a broad spectrum supplement of micronutrients in low or higher doses.  The supplements were found to alleviate the experience of stress, with the biggest dose having the biggest effect.
For instance, foods rich in vitamin E and beta-carotene are healthy and can help reduce cancer risk. However, the U.S. Preventive Services Task Force (USPSTF) and the American Academy of Family Physicians (AAFP) recommend against taking vitamin E or beta-carotene for the prevention of cardiovascular disease. People who smoke or are at risk for lung cancer also should avoid beta-carotene. It can increase their risk of lung cancer.