Amyotrophic lateral sclerosis (ALS), or Lou Gehrig’s disease, is a rapidly progressive motor neuron disease affecting as many as 20,000-30,000 people in the United States. One of the most common neuromuscular diseases worldwide, ALS affects people of all races and ethnic backgrounds, typically between the ages of 40 and 60.
ALS attacks the nerve cells (motor neurons) that control voluntary movement and strength. Motor neurons are located in the spinal cord and brain. In ALS, motor neurons gradually die which interferes with muscle control and movement, ultimately leading to death. The cause of ALS is still unknown although research has identified a genetic risk factor in familial (inherited) cases of ALS which account for 5-10% of all ALS cases diagnosed.
New research published in the Annals of Neurology suggests that the consumption of foods containing colorful carotenoids, particularly beta-carotene and lutein, may prevent or delay the onset of ALS. Previous research has suggested that oxidative stress is involved in the development of ALS and that persons who take vitamin E supplements (a powerful antioxidant) have a reduced risk of ALS.
The current study investigated the role of other antioxidants, including vitamin C and carotenoids, in the risk of developing ALS. Researchers compiled data from five cohort 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 - which totaled more than one million participants and included 1153 documented cases of ALS, 1093 of which were included in the analysis.
"ALS is a devastating degenerative disease that generally develops between the ages of 40 and 70, and affects more men than women," said senior author Dr. Alberto Ascherio in a press release, Professor of Epidemiology and Nutrition at Harvard School of Public Health in Boston, Mass. "Understanding the impact of food consumption on ALS development is important. Our study is one of the largest to date to examine the role of dietary antioxidants in preventing ALS."
Known to be powerful antioxidants, carotenoids are the organic pigments that give fruits and vegetables their bright orange, red, or yellow colors, and are a source of dietary vitamin A. Researchers found that a higher level of total carotenoid consumption was linked to reduced risk of ALS by as much as 25%. It was noted that individuals who ate more carotenoids tended to get more exercise, have an advanced degree, consume more dietary vitamin C, and take vitamin C and E supplements.
After it was established that greater carotenoid intake was associated with reduced ALS risk, researchers looked further to determine which if any particular carotenoid was individually protective. Diets high in beta-carotene and lutein, which are found in carrots, sweet potatoes, and dark green leafy vegetables (also high in vitamin E), are associated with a reduced ALS risk by 26% and 30%, respectively. No association between beta-carotene supplement use and risk was found.
Additionally, researchers found that diets high in lycopene, alpha-carotene, beta-cryptoxanthin, and vitamin C did not affect ALS risk. Long-term vitamin C supplement intake was also not associated with ALS risk.
Authors conclude their findings suggest that consuming carotenoid-rich foods may help to prevent or delay the onset of ALS. Further research that incorporates food-based analyses is needed to determine possible dietary characteristics associated with ALS prevention.
Fitzgerald KC, O’Reilly EJ, et al. Intakes of Vitamin C and Carotenoids and Risk of Amyotrophic Lateral Sclerosis:Pooled Results from 5 Cohort Studies. Annals of Neurology; Published Online: January 29, 2013 (DOI:10.1002/ana.23820).
Amyotrophic Lateral Sclerosis (ALS) Fact Sheet - National Institute of Neurological Disorders and Stroke (NINDS)
Amyotrophic lateral sclerosis - Genetics Home Reference, National Library of Medicine (NLM)
What is ALS? - The ALS Association
National Amyotrophic Lateral Sclerosis (ALS) Registry - Center for Disease Prevention and Control (CDC)