Vitamin D3 2000IU

What Is Vitamin D3?

Vitamin D3, or cholecalciferol, is the form your skin makes when ultraviolet light strikes 7-dehydrocholesterol, a sterol sitting in the outer layers of the skin. The D3 here starts from lanolin, the waxy grease in sheep wool, a rich source of the sterol that precursor is built from. That works out to 50 mcg per serving.

How It Works in the Body

Cholecalciferol does nothing as swallowed. The liver adds one hydroxyl group to make 25-hydroxyvitamin D, the form that circulates and the form a blood test measures. The kidney adds a second to make calcitriol, the active form. Calcitriol binds a receptor inside the cell and switches on genes, including the ones for the proteins that carry calcium across the gut wall.

What It Supports

• Calcium from food: The intestine needs vitamin D to absorb calcium at all, which supports bone health.
• Bones and teeth: Both are mineralized with calcium and phosphate, and vitamin D governs how much of each gets in.
• Muscle function: Skeletal muscle carries the vitamin D receptor, and the vitamin plays a role in normal muscle function.
• A circulating reserve: The 25-hydroxy form stays in the blood for weeks, so daily intake builds a steady supply.

Who It May Suit

People who spend daylight hours indoors, live far from the equator, cover up outdoors or use sunscreen consistently, since skin makes less D3 in each case. Skin also makes less with age and with more melanin in it. The shell is bovine gelatin, so vegetarians should look elsewhere.

Good To Know

Vitamin D is fat-soluble, and this D3 sits in extra virgin olive oil and safflower oil inside a softgel. The body keeps what it does not use, mostly in fat and liver. Talk with your provider before use if you are pregnant, take digoxin or a thiazide diuretic, or have a kidney condition.