Vitamin D: How Much Do You Need, and Why a Blood Test Comes First

What vitamin D does

Your body uses vitamin D to pull calcium from food and build it into bone. It also plays a part in how your muscles and immune system work. Low vitamin D in adults shows up as tiredness, achy bones and muscles, and more colds than usual. Very low vitamin D over a long time softens bone.

How much is enough

The NIH recommends 600 IU a day for adults up to age 70 and 800 IU a day after 70. The safe upper limit for adults is 4,000 IU a day unless a provider tells you otherwise. More is not better: vitamin D is stored in fat, so too much over months can build up and raise blood calcium.

Why the blood test comes first

A simple blood test (25-hydroxyvitamin D) tells you where you stand. Most labs call 20 ng/mL or above enough for bone health, and under 12 ng/mL low. Without that number you are guessing, and guessing high is the one way to get this wrong. We draw the blood at your home anywhere in New York and New Jersey; results come back in a few days and a licensed provider reviews them with you.

Pill, drop or shot?

Most people do fine with a daily pill or drop plus a bit of midday sun. A vitamin D shot is for people whose level is low and who struggle to take or absorb a pill, or who want to catch up faster under a provider's order. Either way, the plan starts from your number, not from a trend.

Not sure where you stand? Book a blood draw at home at zenivspa.com.

All treatments are medical services. Every guest is screened, and every treatment is provided only under the clearance, prescription or standing protocol of a licensed medical provider. Compounded peptides are not FDA-approved unless stated. Nothing on this page is a diagnosis or a promise of results.