Amyotrophic lateral sclerosis Patient friendly summary

  • Solar UVB light produces vitamin D, which may lower Amyotrophic lateral sclerosis risk during fetal development.
  • Vitamin D strengthens the body’s immune system and protects the mother from infection, and may reduce the risk of Amyotrophic lateral sclerosis during fetal development.

Amyotrophic lateral sclerosis (ALS) is a disease of the nerve cells in the brain and spinal cord.

ALS destroys the nerve cells, which control voluntary muscle movement. Early symptoms may include twitching, cramping, or stiffness of muscles; muscle weakness affecting an arm or a leg; slurred and nasal speech; or difficulty chewing or swallowing. These general complaints then develop into more obvious muscle weakness (atrophy).

ALS is also known as Lou Gehrig's disease.

Risk factors

The risk factors for Amyotrophic lateral sclerosis may include:

  • Chemical exposure
  • Occupations with hard manual labor (construction work and athletic sports)
  • Diet high in carbohydrates
  • Maternal infection during pregnancy

Studies have found that all fruits and vegetables, polyunsaturated fatty acid, and vitamin E are associated with a reduced risk of Amyotrophic lateral sclerosis.

Sunlight exposure and Amyotrophic lateral sclerosis risk

There is limited evidence that sunlight exposure or seasonal variation affects the risk of Amyotrophic lateral sclerosis. Seasonal variations would indicate that solar ultraviolet-B (UVB) and vitamin D play a role in ALS. However, there are a few related studies:

  • One study reported that Amyotrophic lateral sclerosis death rates are highest in the northern states of the United States. The northern states have less sun than the southern states.
  • Swiss researchers proposed that infectious diseases may be a risk factor for Amyotrophic lateral sclerosis. They noted that more people with ALS were born in the spring. Solar UVB light is lowest in winter and may cause maternal vitamin D deficiency.

Vitamin D and Amyotrophic lateral sclerosis

Vitamin D levels

There are no reported studies of vitamin D levels and Amyotrophic lateral sclerosis risk or progression.

Vitamin D and calcium

Those with Amyotrophic lateral sclerosis have an increased risk of osteoporosis and bone fractures. Vitamin D and calcium supplementation may reduce this risk.

How vitamin D works

Based on the U.S. incidence of higher Amyotrophic lateral sclerosis death rates in northern states and higher spring births in Switzerland, maternal vitamin D during pregnancy may play a role in reducing ALS risk. Possibly vitamin D lowers the risk of infection by stimulating production of cathelicidin and defensins. These proteins have antimicrobial properties. They fight viral and bacterial infections. They also lower the inflammatory response to viral infections.


Vitamin D may reduce the risk of Amyotrophic lateral sclerosis during pregnancy. This is especially true during the winter and spring. Solar UVB levels are low, and the risk of infection is higher. Based on findings for other diseases, vitamin D levels above 30–40 ng/mL (75–100 nmol/L) are recommended during pregnancy.


Those with Amyotrophic lateral sclerosis should consider increasing vitamin D levels to above 30–40 ng/mL (75–100 nmol/L).

Calcium supplements should also be taken in order to reduce the risk of bone fractures.

Find out more...

We will be adding a detailed evidence summary on this topic in the near future.  Please check back soon to find out more.

Page last edited: 17 May 2011