5 Reasons Some People Breeze Through Cold Season — and Others Don't

Vitamin D supplementation is one of those habits that tends to be seasonal. People take it from October through March, then drop it the second spring hits.

But indoor work, sunscreen, and modern lifestyle patterns mean Vitamin D status often doesn't bounce back the way people assume.

Vitamin D3 + K2 is formulated as a daily foundation to support healthy immune function, healthy teeth, and healthy bones throughout the year.†

Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol) are not interchangeable, even though both are sold as "Vitamin D."

D3 is the form your body produces from sun exposure and the more bioactive form for supplementation.

D2 is sometimes used in fortified foods and prescription supplements, but it's not what your body may recognize by default.

Most Vitamin D supplements stop at D3. But D3 doesn't operate in isolation — Vitamin K2 supports the body's healthy regulation of where the calcium D3 helps you absorb actually goes.†

K2 also plays a role in modulating normal immune cell function. Skipping it means supporting only half the cycle.†

Most Vitamin D gummies cap out at 1,000 to 2,000 IU per serving — a fraction of what a high-potency supplement provides.

They often skip K2 entirely or include MK4, which has a half-life measured in hours rather than the two to three days of MK7.

Most people only think about healthy immune support reactively — once something is going around, or after they've already started feeling off.

Reactive support has its place. But daily foundation nutrients build the baseline so your immune system is supported before it's tested.†

Vitamin D is one of the most studied and most commonly under-supplied of those foundations.