Lack of vitamin D during pregnancy may increase the child's risk of sclerosis

It has long been known that vitamin D deficiencies increase the risk of sclerosis. According to a study that is published in JAMA Neurology, having too little vitamin D is even a problem during pregnancy, as it increases the child's risk of developing sclerosis later in life.

Sclerosis is a progressive disease where the immune defense attacks the myelin sheath that surrounds the neuron fibers, causing a variety of symptoms, all depending on which parts of the central nervous system have been destroyed. Kassandra L. Munger and her team of researchers from Harvard T.H. Chan School of Public Health, Boston, have studied if maternal blood levels of vitamin D during the first three months of pregnancy had any influence on the development of sclerosis in the offspring.
The researchers recruited 193 sclerosis patients whose mothers had participated in a large, Finnish cohort study, a type of study where a closely defined group of people is monitored for a period of time in order to reveal a specific health problem. Afterwards, the researchers compared 176 sclerosis patients with 326 healthy controls.

90 percent higher risk of sclerosis when mothers lack vitamin D

Maternal vitamin D status during pregnancy was determined by measuring levels of active 25-hydroxyvitamin D3 in the blood. Most blood samples were drawn in the first trimester of pregnancy. The samples revealed that the women generally lacked vitamin D, and the risk that their children would develop sclerosis later in life was an alarming 90% higher if the mothers had vitamin D levels below 12.02 nmol/l, compared with children whose mothers did not lack the vitamin. Just for the record, blood levels of vitamin D should normally be above 50 nmol/l, and leading researchers believe that levels should preferably be as high as 75-100 nmol/l in order to obtain the best protection against disease.

Different results

Kassandra L. Munger and her team of scientists do, however, point to earlier studies that have failed to find a link between maternal vitamin D status during pregnancy and risk of sclerosis among the offspring later in life. It is therefore possible that several factors are at play. According to the researchers, the new study has a few limitations, as maternal vitamin D levels during pregnancy do not reflect exactly how much vitamin D the fetus gets. Although the scientists assume that lack of vitamin D during pregnancy does increase the risk of sclerosis in offspring later in life, they say that more research is warranted in order to show the necessity and effect of raising vitamin D levels in the blood.

The relation between climate, diet, biology, and sclerosis

When the before mentioned Finnish cohort study Finnish Maternity Cohort (FMC) was originally launched, the aim was not to show the relation between maternal vitamin D levels in the blood and the risk of the children developing sclerosis. However, according to Dr. Benjamin Greenberg from the University of Texas, different data from the study have been useful to help understand the complex relation between biology and disease. Like other scientists, Benjamin Greenberg has emphasized that sclerosis is more common in the northern hemisphere where people are not exposed to as much sunshine, and where it is only possible to produce vitamin D in the skin during the summer period where the sun sits sufficiently high in the sky. In places like Japan and Alaska the diet contains much more vitamin D from sources like oily fish, fish liver, and seal liver, and this may possibly help to prevent sclerosis.

How does vitamin D protect against sclerosis?

Vitamin D is viewed as a lipid-soluble hormone which all cells depend on. According to scientists, low levels of vitamin D during critical periods of pregnancy may result in the development of weak myelin sheaths that become increasingly vulnerable over time. Also, vitamin D controls the immune defense, which develops additionally after birth, and if the child lacks vitamin D, the risk of autoimmune reactions increases. Such reactions include those where the immune system inadvertently attacks the central nervous system.

The upper safe intake level for vitamin D (updated in 2012)

Experts disagree on the actual need for vitamin D, which depends on many factors such as BMI (Body Mass Index). The upper safe intake level for vitamin D has been set by the EFSA (European Food Safety Authority) at 100 micrograms/day for children older than 11 years and adults, including pregnant and lactating women.

References:

Alberto Ascherio, MD, DrPH et al. Vitamin D Status During Pregnancy and Risk of Multiple Sclerosis in Offspring of Women in the Finnish Maternity Cohort. JAMA Neurol. March 2016
https://archneur.jamanetwork.com/article.aspx?articleid=2499458&atab=8

Benjamin M Greenberg, MD, MHS. Vitamin D During Pregnancy and Multiple Sclerosis: An Evolving Association. JAMA Neurol. March 201