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"Supplement" Sunshine With Vitamin D

While some supplements have a shady reputation, vitamin D is one nutrient that is recommended for almost everyone in the Pacific Northwest. Particularly with rainy season on its way and much more time spent indoors, it’s much more difficult to get enough vitamin D naturally.

“As long as you are a generally healthy adult, 800 to 4,000 IU of vitamin D3 a day on average is fine to take on your own without needing to get your blood tested,” said Sara Lee Thomas, a dietitian at Good Samaritan Regional Medical Center in Corvallis. “Your body is able to balance out vitamin D over time, so if it is easier you can take vitamin D once a week, for example taking 15,000 to 20,000 IU on Sunday, which will average out to around 2,100 to 2,900 IU a day.”  

How to Get Vitamin D

Thomas reports that scientists have found you can’t get enough vitamin D from food, even on a healthy diet. Moderate levels of vitamin D occur naturally in some foods and are supplemented in some foods, but most vitamin D is generated by the body from the sun on our skin. Unfortunately, in Oregon we have a vitamin D “shadow” that lasts from October to April. No matter how sunny the day, the right rays of sunshine are just not available and our bodies can’t make any vitamin D from the sun.

If you add a vitamin D supplement to your diet, Thomas cautions that with vitamin D, like most nutrients, it is bad to have levels too low and bad to have levels too high. She recommends sticking to the daily average of 800 to 4,000 IU vitamin D3 a day unless you have a personalized prescription from your doctor. High blood levels of vitamin D can be toxic, cause calcifications in soft tissues and damage the kidneys and heart.

Conflicting Information

“There is still a lot of debate about the ‘optimal’ blood level of vitamin D to prevent various diseases,” said Thomas. “Some experts are very enthusiastic, but others are concerned. High blood levels of vitamin D have been linked to increased overall death rate. But some studies with disease-specific information show less breast cancer or other diseases at higher levels of vitamin D. The bottom line is we don’t know for sure the optimal blood level for vitamin D so it’s safest to stay within the recommendations until we know more.”

Thomas compares taking a supplement to riding a roller coaster.

“Generally if you go from low to normal vitamin D blood levels there are many benefits, but once you get to the normal range, more of the vitamin doesn’t actually get you more results you get no further benefit as you add more, you just get more risk as you go higher,” she said. “This is the Nutrient Threshold Effect. It’s like being tall enough to get on the roller coaster. Once you’re tall enough the good times start, but if you keep getting taller, it won’t make the ride better, you end up in the same place, and if you keep growing and get very tall at some point the danger begins; better duck down!”

Choosing the Right Supplement

Due to the high incidence of issues with poor quality in the supplement industry, Thomas recommends looking for vitamin D with a seal from an independent testing facility such as the USP, NSF or, or that is listed on the website.

“Many people take supplements, so it’s important to be smart about which supplements you take and how much you’re taking,” said Thomas. “It is very important to share which vitamins and supplements you are taking with your doctor and have the information recorded in your medical record, even if you only take them occasionally. Supplements can interfere with medication, surgery and even regular nutrition.”

If you’re not sure if you’ve shared your supplements with your provider, log into MyChart to check your medical record medication list. If you don’t see the supplements you’re taking listed, be sure to let your provider know on your next visit.