Hi tinglytoes,

Vitamin D2 can cause an upset stomach and other uncomfortable digestive issues. Vitamin D3 is less likely to do that because our body recognizes it as a friendly, natural substance..... similar to sun exposure.

Here is a piece from the vitamin d council with regard to not supplementing but rather "letting" the sun do it for us....

Understanding Vitamin D Cholecalciferol

The high rate of natural production of vitamin D3 cholecalciferol (pronounced koh·luh·kal·sif·uh·rawl) in the skin is the single most important fact every person should know about vitamin D—a fact that has profound implications for the natural human condition.

Technically not a "vitamin," vitamin D is in a class by itself. Its metabolic product, calcitriol, is actually a secosteroid hormone that targets over 2000 genes (about 10% of the human genome) in the human body. Current research has implicated vitamin D deficiency as a major factor in the pathology of at least 17 varieties of cancer as well as heart disease, stroke, hypertension, autoimmune diseases, diabetes, depression, chronic pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, periodontal disease, and more.

Vitamin D's influence on key biological functions vital to one's health and well-being mandates that vitamin D no longer be ignored by the health care industry nor by individuals striving to achieve and maintain a greater state of health.

Sunshine and Your Health......If well adults and adolescents regularly avoid sunlight exposure, research indicates a necessity to supplement with at least 5,000 units (IU) of vitamin D daily. To obtain this amount from milk one would need to consume 50 glasses. With a multivitamin more than 10 tablets would be necessary. Neither is advisable.

The skin produces approximately 10,000 IU vitamin D in response 20–30 minutes SUMMER sun exposure—50 times more than the US government's recommendation of 200 IU per day!

How To Get Enough Vitamin D:
There are 3 ways for adults to insure adequate levels of vitamin D:
•regularly receive MIDDAY sun exposure in the LATE SPRING, SUMMER and EARLY FALL, exposing as much of the skin as possible (being careful to never burn).
•regularly use a sun bed (avoiding sunburn) during the colder months.
•take 5,000 IU per day for 2–3 months, then obtain a 25-hydroxyvitamin D test. Adjust your dosage so that blood levels are between 50–80 ng/mL (or 125–200 nM/L) year-round.

Vitamin D's Co-factors:
Vitamin D has co-factors that THE BODY NEEDS in order to utilize vitamin D properly. They are:
•magnesium
•zinc
•vitamin K2
•boron
•genestein
•a tiny amount of vitamin A

Magnesium is the most important of these co-factors. In fact, it is common for rising vitamin D levels to exacerbate any underlying magnesium deficiency. If one is having problems supplementing with vitamin D, a MAGNESIUM deficiency could be the reason why.
End of literature.

Most supplements are synergistic. This means that they need other supplements in order to be effective. This fact is so important to know because it can be a waste of time and money if we are not properly absorbing and utilizing the supplements that we take.

Hope this info is helpful!

Bryanna