Having a low level of vitamin D greatly increases a person’s risk of age-related loss of muscle strength (known as dynapenia), a major risk factor for falls, a new study suggests.

The study, published online Sept. 15, 2022, by the journal Calcified Tissue International and Musculoskeletal Research, analyzed data from more than 3,200 people ages 50 and older with no previous dynapenia. Researchers tracked them for four years as part of the English Longitudinal Study of Aging, a long-term study that began in 2002. Participants’ vitamin D levels were measured with blood tests at the start and categorized as sufficient (defined as more than 50 nanomoles per liter, or nmol/L), insufficient (30 to 49 nmol/L), or deficient (less than 30 nmol/L). After four years, grip strength was evaluated as a measure of participants’ overall muscle strength.

People deficient in vitamin D were 70% more likely to develop dynapenia by the end of the study than those with normal vitamin D levels. The results make sense, researchers said, since vitamin D is known to help with muscle repair and contraction. People can avoid vitamin D deficiency through careful sun exposure, eating foods rich in the vitamin, or taking a supplement