What does a vitamin D level of 33 mean? Are there any symptoms associated with this vitamin D level?

A vitamin D level of 33 ng/mL is considered low. Low levels of vitamin D can occur from prolonged, inadequate intake through diet, limited exposure to sunlight, poor kidney function, or inadequate vitamin D absorption. 

Low vitamin D can negatively affect your health and put you at increased risk for, and severity of COVID-19, diabetes, and cancer. It may also increase your risk for certain autoimmune and neurodegenerative diseases like multiple sclerosis and Alzheimer’s.  

Factors that could contribute to a vitamin D level of 33

• Diet low in vitamin D

• Older age (partly due to a decline in the skin’s ability to synthesize vitamin D with age)

• Dark complexion

• Living in cold or northern climates (people who live above 37°N latitude cannot synthesize vitamin D year-round)

• Limited sun exposure (such as those who spend the majority of their time indoors or are covered when outside)

• Pregnancy and breastfeeding

• Conditions that interfere with vitamin D absorption or synthesis including Cystic fibrosis, Crohn's, celiac, kidney, and liver disease

• Obesity (greater amounts of subcutaneous fat sequester more of the vitamin)

• Gastric bypass surgery

What to do if your vitamin D level is 33?

To improve vitamin D levels:

• Increase your consumption of vitamin D-rich foods. Good sources include 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. How much you should take depends on your level of deficiency. For a level of 33, you will likely need to take 2,000-5,000 IU daily for several months to significantly improve your vitamin D status. 

• If levels do not improve after 3 months, review your supplements with an expert or talk to your doctor. 

Supplements used to improve vitamin D test results

If you are low in vitamin D, a daily supplement is typically needed to get levels into the optimal range (40-80 ng/mL) over time. 

For levels of 33 ng/mL, consider talking to your healthcare provider. Daily supplementation of vitamin D3 (cholecalciferol) should be considered to achieve adequate body stores of vitamin D.