Optimizing Vitamin D Levels

Vitamin D can be obtained from three sources: food, ultraviolet light (sun and UV lamps), and supplements. Since each person’s vitamin D is affected differently by sunlight, nutrient absorption from food and supplements, and mobilized body stores, there is no one-size-fits-all guideline. Sunlight or UV exposure is the optimal source of vitamin D and accounts for the majority of 25(OH)D serum levels in the absence of supplementation. With the winter months upon us, we have less daylight hours, typically spend less time outdoors, and are usually all bundled up preventing much skin from actually being exposed to the sun. The range of serum 25(OH)D, which the majority of researchers agree, that avoids deficiency or toxicity is between 30 and 60 or 65 ng/mL. 

Food Sources of Vitamin D

Food (3.5 oz. unless otherwise specified); IU per serving

High-vitamin cod liver oil (1/2 tsp.) 2,000

Indo-Pacific marlin 1,400

Herring 1,100

Fatty bluefin tuna 720

Duck egg 720

Chicken egg (pastured) 480–720

Rainbow trout 600

Eel 200–560

Mackerel 345–440

Standard cod liver oil (1 tsp.) 400

Sockeye salmon 360

Canned sardines 270

Chicken egg (conventional) 120

Pork liver 50

Beef liver 13.5

Chicken liver 30

Pork 28

Sun Exposure

As a general rule, mid-summer full-body skin exposure produces 10,000 IU in about half the time it takes your skin to turn pink. This could be just 15 minutes for pale skin types.

At higher elevations, for darker skin colors, or with less skin exposed, much less vitamin D is produced.

Recommended Sun Exposure by Season

Late fall, winter, and early spring: Spend about half as much time as it takes for skin to turn pink outside three to seven times per week.

Late spring, summer, and early fall: Spend half as much time as it takes for skin to turn pink outside at least three times per week.

Supplementation Considerations

Take with fat for maximum absorption.

D3 is better absorbed than D2.

Your dose should be adjusted according to your weight.

Weekly or daily dosing is similarly effective.

Avoid monthly or semi-annual mega-doses.

%d bloggers like this: