Vitamin D for Brain Health

What is Vitamin D & Why is it Important for Brain Health?

Vitamin D is a fat-soluble vitamin that is mainly known for its ability to maintain bone health through its assistance with calcium absorption; however, it also plays a critical role in brain development and functioning. 

Vitamin D interacts with Vitamin D receptors (VDRs), some of which are located in the brain, and is involved in a variety of functions [1]:

• Increasing neurite growth for neuronal development and signaling
• Regulating the development of dopamine neurons 
• Protecting neurons from damage caused by reactive oxygen species(ROS), inflammation, and stress (e.g. regulates calcium influx, increases antioxidants, blocks production of inflammatory cytokines) 
• Promoting the expression of neurotrophic factors (e.g. NGF, GDNF, BDNF) that are important for cell survival, as well as cell proliferation and differentiation

This vitamin is especially important in newborns and developing children. Research has found that Vitamin D deficiencies are common in pregnant mothers and may increase the risk of neonatal brain injuries, as well as affect neuronal development and pruning in children [2]. 

Additionally, Vitamin D deficiencies (aka hypovitaminosis D) are commonly seen in individuals over the age of 65. These deficiencies may be associated with accelerated brain aging, reduced gray matter volumes, mild cognitive impairment, and an increased risk of dementia [3, 4]. In fact, as many as 70-90% of Alzheimer’s patients have been found to be deficient in Vitamin D [5]! 

Meeting Vitamin D Needs 

The Recommended Dietary Allowance (RDA) is 600 IU (15 mcg) daily for individuals between the ages of 1 and 70, and 800 IU (20 mcg) daily for individuals over 70 [6]. Some foods that contain high amounts of Vitamin D are: 

• Fatty fish (e.g. salmon, tuna, sardines)
• Mushrooms exposed to UV light
• Fortified milks and cereals

However, one of the best ways to meet your Vitamin D needs is to catch some rays! When Type B UV (UV-B) radiation from the sun hits your skin, it breaks down a compound called 7-dehydrocholesterol to previtamin Vitamin D3, which then rapidly converts to Vitamin D3 [6]. Research suggests that getting just 5-30 minutes of sun daily/twice a week can generate an adequate amount of Vitamin D. 

Vitamin D Supplements

Some groups have a higher risk of developing a Vitamin D deficiency [6]:

• Individuals with conditions that interfere with fat absorption (e.g. liver disease, cystic fibrosis, celiac disease, Crohn’s disease, ulcerative colitis) 
• Individuals who have undergone gastric bypass surgery (part of the upper small intestine - where Vitamin D is absorbed - is bypassed)
• Older individuals who may spend less time outdoors and have a reduced ability to synthesize Vitamin D through their skin 
• Individuals who have limited sun exposure 
• Individuals who are unable to consume Vitamin-D rich foods 

As such, it may be necessary for these individuals to take supplements to get adequate amounts of Vitamin D. 

There are two types of supplements: Vitamin D2 (aka ergocalciferol) and Vitamin D3 (aka cholecalciferol) [6]. Vitamin D2 is mainly found in plant sources and fortified foods, while Vitamin D3 is mainly found in animal sources, and both are metabolized into calcifediol (major circulating form of Vitamin D). Vitamin D3 supplements appear to be more effective than Vitamin D2 at raising and sustaining blood levels of calcifediol; however, additional research is required [7]. 

References

1. Cui and Eyles, 2022: https://doi.org/10.3390/nu14204353 
2. Stessman and Peeples, 2018: https://doi.org/10.1159/000486819 
3. Moon et al., 2015: https://doi.org/10.1111/cen.12733 
4. Sommer et al., 2017: https://doi.org/10.1186/s12877-016-0405-0 
5. Di Somma et al., 2017: https://doi.org/10.3390/ijms18112482 
6. National Institutes of Health, Office of Dietary Supplements, 2023: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#h4 
7. Tripkovic et al., 2012: https://doi.org/10.3945/ajcn.111.031070