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Children and youngsters living in sunny climates are less likely to develop sclerosis later in life

Children and youngsters living in sunny climates are less likely to develop sclerosis later in lifeChildren and youngsters who are exposed to lots of sunlight and have plenty of vitamin D in their blood are much less likely to develop sclerosis later in life, according to a new study. In fact, there is a reason why sclerosis is more prevalent at northern latitudes. During the winter, the sun sits too low in the sky for us humans to be able to synthesize vitamin D in the skin. However, one must also realize that the intensified use of sunscreen can block the skin’s production of vitamin D. It is therefore essential to get plenty of vitamin D from sun exposure or to take a vitamin D supplement, as this may help prevent diseases such as sclerosis that take years to develop.

Over the past decades, experts have warned people against direct sun exposure during the middle of the day and also to avoid sunburns, as this increases the risk of skin cancer. However, these warnings against the sun combined with the intensified use of sunscreen have contributed to widespread vitamin D deficiency. Many people, including children and youngsters, are pale all year round, which is a sign that they are not getting enough sun and therefore lack vitamin D, unless they take a supplement. Getting too little sun can be every bit as dangerous as getting too much. Not only are low levels of vitamin D in the blood linked to a greater risk of developing sclerosis, it also increases the risk of osteoporosis, infections, cancer, and many other diseases.

Sclerosis is an autoimmune disease that is also known as multiple sclerosis (MS) or disseminated sclerosis. It is characterized by repetitive attacks on different parts of the central nervous system. These attacks can lead to a host of different symptoms.

The new study looked at where the participants live and how much sun they get

Earlier research has shown that sclerosis is less prevalent in sunny parts of the world. The scientists behind the new study from the University of British Columbia in Vancouver, Canada, took it a step further by looking at people’s lifelong exposure to the sun and how that affected them. It turned out that the risk of developing sclerosis hinges on where you grow up and to how much UVB radiation you expose yourself.
The scientists collected data from a large study called Nurses’ Health Study and looked closer at 151 nurses with sclerosis and 235 nurses without the disease. Both groups of women were the same age. They lived in different American states with different climates and landscapes. The majority of the women (98 percent) were white. All participants filled in questionnaires with information about how much sun they generally got in the summertime and in the wintertime. The scientists divided the women in three groups (low, moderate, and high UVB exposure) depending on their exposure to sunlight. These groups were associated with the women’s residential area and its geographical location, altitude, and average cloud cover. The researchers also took into account the participants sunbathing habits. Here, they defined “comprehensive sun exposure” as more than ten hours of weekly sun exposure during the summer period and more than four hours weekly during winter.

The reason why sclerosis has such a debilitating impact is that the T-lymphocytes of the immune system attack the protective myelin sheath that surrounds the nerve fibers. Vitamin D plays a crucial role because it helps control the overactive immune defense.

Generous sun exposure lowers your risk of sclerosis by 45-55 percent

The researchers found that women living in sunny climates who exposed themselves to the highest amount of UVB rays were 45 percent less likely to develop sclerosis compared with the women who had the lowest UVB exposure.
When looking closer at the different age groups, the scientists found that the risk of developing sclerosis was 51 percent lower among women who had been living in sunny climates from they were five to fifteen years of age. Those women who had spent a lot of time in the sun during the summer at the ages of 5-15 years had a 55 percent lower risk of sclerosis compared with those who got the least sun.
The average age for women with sclerosis was 40 years. According to the scientists, female sclerosis sufferers had generally spent less time in the sun because of living in sun-deprived climates and spending more time indoors. This, the researchers point out, shows the importance of exposing ourselves to plenty of sunlight throughout all stages of life. Lack of sunlight and vitamin D can have a detrimental impact on our health.
Their study, which is published in the science journal Neurology, has certain limitations, however, as its results are based on the personal recollection and self-reporting of each participant. Still, the latitude and average cloud cover for each different area say a lot about sun exposure.
Another limiting factor is that the majority of study participants were white women, which means the study results cannot be extrapolated to those with darker skin. The darker the skin you have, the better your protection against sunburns, but it also means reduced skin synthesis of vitamin D. In other words, people with dark skin are more likely to become vitamin D-deficient if they live in areas with limited sunshine.
It is also known that people who are overweight or have diabetes have difficulty with producing enough active vitamin D. Therefore, it is a good idea to ask your physician to measure levels of the nutrient in your blood.

Vitamin D levels in your blood predict your risk of sclerosis

An earlier study, which was also published in Neurology, shows that low levels of vitamin D in the blood is a sign of an increased risk of developing sclerosis. It is possible to reduce the risk of sclerosis by around 40 percent by optimizing your blood levels of vitamin D. The study defined actual vitamin D deficiency as levels below 30 nmol/l (nanomoles per liter of blood). Vitamin D insufficiency was defined as having levels of around 30-49 nmol/l, whereas levels of 50 nmol/l or more were considered sufficient.

Make sure to

gradually adjust yourself to the sun, beginning in early spring. The step-by-step darkening of your skin will help protect you against sunburns

Actual need for vitamin D, supplements, and absorption

Many scientists claim that our actual need for vitamin D is a lot higher than the reference intake (RI) level. Recommendations vary from 30 to 100 micrograms daily, an amount that we humans can easily synthesize on a hot summer day. Our diets only provide limited quantities of vitamin D, which means that supplements are necessary during the winter period and in situations where people for some reason or another are unable to produce enough of the nutrient from sun exposure. Vitamin D is a lipid-soluble nutrient, which means that supplements should ideally contain vitamin D in some sort of oil.


- the summer sun is good for you because it is the richest source of vitamin D. Expose yourself to 20-30 minutes of unprotected sunshine and apply sunscreen if you want to spend more time in the sun (especially if you have delicate skin).


American Academy of Neurology. Living in a sunnier climate as a child and young adult may reduce risk of MS. ScienceDaily March 7, 2018

Vitamin D levels in blood may help predict risk of multiple sclerosis. Medicalxpress 2017

Sotirchos et al. Safety and immunologic effects of high- vs low-dose cholecalciferol in multiple sclerosis. Neurology 2016

Alberto Ascherio et al. Vitamin D as an Early Predictor of Multiple Sclerosis Activity and progression. Jama Neurology 2014

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