It was the Harvard School of Public Health that suggested taking a multivitamin once per day will give people the additional vitamin D that they need and the Linus Pauling Institute’s Micronutrient Information Center at Oregon State University that stating taking a multivitamin each day is essential to maintaining optimal health.
Experts can agree that vitamin supplements can help bridge any nutrient gaps in your daily diet and support your general health while also preventing health risks or major chronic conditions. For example, pregnant women can take folic acid supplements to reduce their risk of birth defects. Older men and women can take vitamin D and calcium supplements to reduce the risk of osteoporosis.
There is a greater risk of having deficiencies in your diet than there is of overdosing on your vitamins. The potential harm comes from a diet that is poor in vitamins and nutrients, not from taking vitamin supplements.