I started taking D3 last fall, and it has made a big difference in how I feel. I started with 3600IU for a few months and when I started feeling more energetic

I started taking D3 last fall, and it has made a big difference in how I feel. I started with 3600IU for a few months and when I started feeling more energetic and cheerful dropped down to 2600 (2x 1000IU + 600IU & calcium). I get outside quite a bit, but in Vancouver WA the skies are overcast a lot and the low sun angle means you can't get enough for vitamin D needs. I also take a probiotic, an anti-oxidant, a fish oil and a green tea supplement. My diet is mostly paleo. My ancestry is northern European. For reference, you need to take 50,000IU for several months to develop toxicity (ref: http://www.mayoclinic.com/health/vitamin-d-toxicity/AN02008 http://www.mayoclinic.com/health/vitamin-d-toxicity/AN02008). If you are pale skinned and don't spend a lot of time in the sun, you are much more likely to be deficient. If you really want to see where you're at, have your doctor do a blood test, or go get a micro-nutrient test http://www.spectracell.com/mnt/ http://www.spectracell.com/mnt/