Vitamin D, nicknamed the sunshine vitamin because your body produces it after sun exposure, has long been known to help build strong bones by increasing the body’s absorption of calcium and phosphorous. [1]https://www.health.harvard.edu/staying-healthy/taking-too-much-vitamin-d-can-cloud-its-benefits-and-create-health-risks Your vitamin D levels reflect many factors like where you live. If you live in the northern states (latitudes north of 37°), you are at higher risk for a vitamin D deficiency because your skin may not be able to produce any vitamin D from sun exposure during the winter months. Your skin’s ability to produce vitamin D drops with age. If you’re over age 65, you generate only one-fourth as much vitamin D as you did in your 20s.
So Vitamin D is very important, but how long does it take for vitamin D to work? According to Drugs.com[2]https://www.drugs.com/medical-answers/long-vitamin-work-3555995/, it could take weeks or months, depending on where your levels are now. Vitamin D deficiency and the impact of getting enough or too much of the nutrient have been the topic of numerous studies.
That includes variations in how much vitamin D people should take or doctors should prescribe and for how long. One 2011 protocol from the Endocrine Society suggests a very high dose of vitamin D3: 50,000 IU, once a week for two to three months or three times a week for one month to restore the nutrient in the body to above 30 ng/mL for those who are deficient. That would be followed by a specific maintenance dose or a variable dose based on a person’s weight.
Therefore, it may take up to 2 to 3 months to bring levels of vitamin D up, depending on how deficient you are.
Yet, the recommended daily allowance of vitamin D in the United States is 600 IUs for adults up to age 70 and 800 IUs after age 70. People at high risk of vitamin D deficiency may need more, but how much and for how long can be determined by your doctor.