Vitamin D is a nutrient your body needs for building and maintaining healthy bones. Vitamin D also regulates many other cellular functions in your body. Its anti-inflammatory, antioxidant, and neuroprotective properties support immune health, muscle function, and brain cell activity.
Vitamin D: New studies suggest that people with low blood levels of vitamin D are more likely to get sick. Researchers think that vitamin D may play a role in boosting immunity.
If you are an adult, you should consider taking up to 4000 IU of vitamin D per day during the winter. I personally passed the age of 70 several years ago. I take 10,000 IU of vitamin D3 daily, plus other vitamins.