Vitamin D and Sunshine: Make the Most of a Sunny Seattle Day

On By Dr. Scott RennieIn Other Diseases and Conditions

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Vitamin D has been in the spotlight for years now. In younger people, most of what we need can usually come from the sun. Mayo Clinic notes that even 10 minutes of sun exposure may be enough to prevent deficiencies. Yet when we actually measure vitamin D in patients, we see that a large number are still deficient.

Does that mean we’re not getting enough sunlight? In some places, probably. Living in Seattle, for example, where sunny days are limited and sunscreen is used frequently, low levels make sense. It also points to the role of diet. Foods like fatty fish, eggs, fortified milk, and cod liver oil provide vitamin D, but many people don’t get enough of those either.

So what happens if your vitamin D levels are too low? Media reports have linked deficiency with a long list of conditions: diabetes, high blood pressure, multiple sclerosis, certain cancers, depression, fatigue, osteoporosis, fractures, peripheral vascular disease, rheumatoid arthritis, Parkinson’s, Alzheimer’s, prostate cancer, weight gain, and even seasonal affective disorder. The list is long.

The important thing to know is that most of these links come from observational studies. That type of study can show association but doesn’t prove cause and effect. Research is still ongoing. What we do know with more confidence is that vitamin D deficiency reduces calcium absorption, which contributes to osteoporosis. Low bone density makes bones fragile, and even a minor fall can result in a fracture.

How do you know if your level is too low? If you have a diet that includes vitamin D-rich foods and you get regular sun exposure, you’re probably fine. But certain risk factors raise the likelihood of deficiency. These include obesity, darker skin tones, older age, breastfeeding in infants, inflammatory bowel disease such as Crohn’s or ulcerative colitis, cystic fibrosis, and some seizure medications. The elderly, in particular, have a reduced ability to produce vitamin D in their skin when exposed to sunlight.

The test we use is called 25-OH vitamin D. It’s a simple blood test that your medical provider can order. I use it often for patients who are at risk or have symptoms that raise concern. From there, we work together to bring levels into the recommended range.

Can you get too much vitamin D? Yes. Excess supplementation can cause hypervitaminosis D, which leads to symptoms like constipation, loss of appetite, dehydration, fatigue, irritability, muscle weakness, and vomiting. This is why it’s important to check in with your medical provider before starting high doses.

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

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