What is the most important vitamin for your body?

What is vitamin D and what does it do? 

• Limited sun exposure: Sun exposure is the best way to get vitamin D but today people are spending more time indoors and avoiding the sun to minimize sun damage and skin cancer risk. 
• It’s difficult to obtain through food: Few foods contain vitamin D, which makes it difficult to consume enough from food alone. It’s found mostly in fatty fish and fortified dairy products.
• Older age: Vitamin D synthesis in skin declines gradually with older age.
• Dark complexion: Melanin in dark skin reduces the skin’s ability to absorb UV radiation needed to synthesize vitamin D.
• Living in cold or northern climates: People who live above 37°N latitude typically don’t get enough sun to synthesize vitamin D year-round.
• Pregnancy and breastfeeding: Pregnant or breastfeeding women have increased vitamin D needs.
• Obesity: Subcutaneous fat appears to sequester more of the vitamin, often resulting in low vitamin D levels.
• Certain health conditions: Some conditions including cystic fibrosis, Crohn's disease, celiac disease, kidney or liver diseases, can interfere with vitamin D absorption and/or synthesis. People who have had gastric bypass surgery are also at greater risk for deficiency due to decreased absorption. 

How to get enough vitamin D

• Increase consumption of vitamin D-rich foods like salmon, herring, canned tuna, eggs (with the yolk), and fortified foods like milk, yogurt, and breakfast cereals.
• Get 10–30 minutes of unprotected midday sunlight most days.
• Take a vitamin D supplement. Dosage will depend on your vitamin D level. For very low levels (<20 ng/mL) you may need to take 5,000 IU daily for several months to significantly improve your vitamin D status. For those in the 20-40 ng/mL range, a daily dose of around 2,0000 IU may be adequate, however it’s best to work with a health professional.