Vitamin D plays a vital role in regulating the immune system, prompting researchers to investigate its connection to autoimmune diseases like multiple sclerosis and type 1 diabetes, and its potential to bolster defenses against infectious diseases such as the flu and tuberculosis. Let’s delve into Which Food Has Vitamin D and how it impacts our health.
Vitamin D and Multiple Sclerosis (MS)
The incidence of multiple sclerosis (MS) is increasing globally, with genetics and environmental factors like inadequate vitamin D and UVB exposure contributing to the risk. The idea that vitamin D plays a role in MS emerged over 40 years ago, driven by observations of higher MS rates in regions far from the equator and lower rates in areas with diets rich in fish.
A prospective study revealed that women with a daily vitamin D intake exceeding 400 IU had a 40% lower risk of MS. Similarly, a study in the US found that White adults with the highest vitamin D serum levels had a 62% lower risk of developing MS compared to those with the lowest levels. Research from Sweden and Finland corroborate these findings, showing a decreased risk of MS with higher serum vitamin D levels. Furthermore, higher vitamin D levels have been linked to reduced disease activity and progression in individuals with MS.
Current evidence suggests that low vitamin D may have a causal role in MS, and correcting vitamin D insufficiency could potentially prevent approximately 40% of cases. This is supported by recent evidence indicating that genetically determined low levels of vitamin D predict a higher risk of multiple sclerosis.
Vitamin D and Type 1 Diabetes (T1D)
Type 1 diabetes (T1D) exhibits geographic variations, with significantly higher rates in Finland compared to Venezuela. While genetics play a significant role, some studies suggest that T1D rates are lower in sunnier regions.
Early evidence supporting the role of vitamin D in T1D comes from a 30-year study following Finnish children from birth. The study revealed that children who regularly received vitamin D supplements during infancy had a nearly 90% lower risk of developing type 1 diabetes than those who did not receive supplements.
However, studies examining the association between dietary vitamin D or trials supplementing children at high risk for T1D with vitamin D have produced mixed and inconclusive results. A prospective study among healthy young adults in the US found that White individuals with the highest levels of serum vitamin D had a 44% lower risk of developing T1D in adulthood than those with the lowest levels. More research is necessary to draw definitive conclusions in this area.
Vitamin D, Flu, and the Common Cold
The seasonal nature of the flu, with increased prevalence in winter and abatement in summer, led to the hypothesis that a sunlight-related stimulus might trigger outbreaks. It has been suggested that vitamin D could be this seasonal stimulus. Vitamin D levels are lowest in the winter, and the active form of vitamin D can temper inflammatory responses while boosting immune cell production of microbe-fighting proteins. Studies have also shown that children with vitamin D deficiency are more prone to respiratory infections, while those exposed to sunlight seem to have fewer infections. Adults with low vitamin D levels are also more likely to report recent respiratory infections.
A randomized controlled trial involving Japanese school children showed that daily vitamin D supplementation (1,200 IU) resulted in a 40% lower rate of type A influenza compared to a placebo group.
A large meta-analysis indicated that daily or weekly vitamin D supplementation lowers the risk of acute respiratory infections, particularly in individuals with significant vitamin D deficiencies. The findings from this meta-analysis have raised the possibility that low vitamin D levels may also increase the risk or severity of COVID-19 infection.
While more research is needed to confirm vitamin D’s protective effects against the flu and other respiratory infections, maintaining adequate vitamin D levels is reasonable, especially for those with darker skin or limited sun exposure. Supplementation with 1000 or 2000 IU per day is a common and inexpensive practice, found in many multivitamin supplements.
Vitamin D and Tuberculosis (TB)
Historically, sunlight and sun lamps were standard treatments for tuberculosis (TB). Research suggests a link between vitamin D and TB risk. Case-control studies indicate that individuals diagnosed with TB tend to have lower vitamin D levels than healthy individuals of similar age and characteristics. Genetic differences in the receptor that binds vitamin D may also influence TB risk.
More research is necessary to determine whether vitamin D deficiency leads to increased TB risk or if vitamin D supplementation can prevent TB.
Vitamin D and Other Autoimmune Conditions
The Vitamin D and Omega 3 trial (VITAL) found that taking vitamin D supplements (2,000 IU/day) for five years reduced the incidence of autoimmune diseases by about 22%, compared with a placebo. Autoimmune conditions observed included rheumatoid arthritis, psoriasis, polymyalgia rheumatica, and autoimmune thyroid diseases. The authors recommended further trials to test the effectiveness of these supplements in younger populations and those at high risk of developing autoimmune diseases.
In conclusion, Vitamin D, obtainable through food, sunlight, and supplements, presents numerous benefits to your health.
