New research out of the Netherlands suggests that sun exposure, and not necessarily vitamin D, might be the key to easing common depressive and fatigue symptoms in multiple sclerosis.
To date, there has been much research whether vitamin D can prevent MS. Or, for those who already have MS, if vitamin D can slow the progression of the disease or help remit the disease or help reduce brain lesions.
However, no one has yet looked to see if vitamin D might help those with MS for some of the symptoms they suffer from, things like depression, anxiety, fatigue and cognitive impairment. Fatigue is the most common symptom of MS, with up to 92% of patients suffering from fatigue. Depression (40%), anxiety (20-40%) and cognitive impairment (40-70%) are common symptoms, too.
In this present study, researchers led by Dr Knippenberg of Maastricht University wanted to look at these very symptoms, and see if they correlated at all to vitamin D blood levels or sun exposure.
So the researchers looked at 198 MS patients between 2002 and 2005. They followed these patients for a mean of 2.3 years. Researchers assessed patients’ vitamin D levels by blood draw, sun exposure habits via a questionnaire, depression and anxiety via the HADS scale, fatigue via the FSS scale and cognition via the PASAT scale. All but cognition were assessed twice per year. Cognition was assessed once per year, each winter.
The researchers wanted to know, was there any correlation between vitamin D, sun exposure and these symptoms? Here’s what they found:
- Mean vitamin D levels were 26.2 ng/ml in the summer (range of 7.5 to 53.1 ng/ml) and 15.7 ng/ml in the winter (range of 6.9 to 28.9 ng/ml). This is pretty good evidence that none of the participants were supplementing with “physiologic” doses of vitamin D, which makes sense given the study period (2002-05).
- At the time of assessment, those with vitamin D levels over 32 ng/ml had lower depression scores than those under 16 ng/ml. For sun exposure, every hour increase in sun exposure per day correlated with decrease in depression scores. When placed into categories of sun exposure per day, those who received 3.5 hours or more of sun exposure per day had the lowest depression scores. When the researchers adjusted for physical exercise, this relationship still remained.
- Neither vitamin D levels nor sun exposure correlated with anxiety scores.
- Neither vitamin D levels nor reported supplement use correlated with fatigue. Sun exposure, on the other hand, was associated with fatigue, the more sun exposure the less fatigue, even after they adjust for confounders.
- Neither vitamin D levels nor sun exposure correlated with cognition (HADS scale).
Also, in general, when the researchers looked for prospective relationships, rather than cross-sectional relationships listed above, they could not find any statistical significant relationship between vitamin D levels or sun exposure on depression, anxiety, fatigue and cognition down the road. Meaning when they looked at sun exposure at a baseline time and whether that helped 6 or 12 months later, there was no relationship. Thus, “reverse causality” could not be ruled out in any of the above findings, which puts the effect of sun exposure on these symptoms in doubt. Especially when you can’t help but think that high fatigue and depression would lead to sun avoidance.
The researchers state,
“In conclusion, we observed that higher levels reported sun exposure, rather than 25(OH)D levels, were associated with less depressive symptoms and levels of fatigue, after mutually adjusting for each other. There was some evidence that 25(OH)D levels above 32 ng/ml were inversely associated with depressive symptoms, and vitamin D supplementation trials will have to confirm whether high levels of vitamin D have the capacity to reduce these symptoms in MS.”
The researchers also note that future studies should investigate the extended effects of sunlight and UV, too, if there are any at all. This present study is a good reminder that until research shows otherwise, we cannot always assume we reap the same benefit in supplementing with vitamin D as we do in getting sun exposure.