You cannot overdose on vitamin D through exposure to sunlight, though you can from supplements. If you choose to take vitamin D supplements, 10 micrograms a day will be enough for most people, according to the NHS. You should not take more than 100 micrograms of vitamin D a day as it could be harmful.
The Cleveland Clinic says ataxia, a neurological condition that may cause slurring of words and stumbling, is a sign of having taken too many vitamin D supplements.
Nonetheless, vitamin D deficiency has also been linked to neurological diseases and neuropsychological disorders, cognitive impairment and neurodegenerative disease.
Read more at: https://www.express.co.uk/life-style/health/1579577/vitamin-d-supplements-too-many-ataxia-slurred-speech