New research suggests that increased consumption of foods containing colorful carotenoids, particularly beta-carotene and lutein, may prevent or delay the onset of amyotrophic lateral sclerosis (ALS). The study, published by Wiley in Annals of Neurology, a journal of the American Neurological Association and Child Neurology Society, found that diets high in lycopene, beta-cryptoxanthin and vitamin C did not reduce ALS risk.

Carotenoids give fruits and vegetables their bright orange, red or yellow colors, and are a source of dietary vitamin A. Prior studies report that oxidative stress plays a role in the development of ALS. Further studies have shown that individuals with high intake of antioxidants, such as vitamin E, have a reduced ALS risk. Because vitamin C carotenoids are also antioxidants, researchers examined their relation to ALS risk. ALS is a progressive neurological disease that attacks nerve cells (neurons) in the brain and spinal cord, which control voluntary muscles. As the upper and lower motor neurons degenerate, the muscles they control gradually weaken and waste away, leading to paralysis.

Using data from five prospective groups: the National Institutes of Health (NIH)–AARP Diet and Health Study, the Cancer Prevention Study II-Nutrition Cohort, the Multiethnic Cohort, the Health Professionals Follow-up Study and the Nurses’ Health Study, researchers investigated more than 1 million participants for this analysis. A total of 1,093 ALS cases were identified after excluding subjects with unlikely food consumption.

The team found that a greater total carotenoid intake was linked to reduced risk of ALS. Individuals who consumed more carotenoids in their diets were more likely to exercise, have an advanced degree, have higher vitamin C consumption and take vitamin C and E supplements. Furthermore, subjects with diets high in beta-carotene and lutein—found in dark green vegetables—had a lower ALS risk. Researchers did not find that lycopene, beta-cryptoxanthin, and vitamin C reduced the risk of ALS. Long-term vitamin C supplement intake was also not associated with lower ALS risk.