Vitamin

Vitamin d3

Vitamin D3, or cholecalciferol, is converted first in the liver and then in the kidneys into its biologically active form. That active form helps regulate calcium and phosphorus absorption.

It contributes to normal bone maintenance, muscle function and immune-system activity.

In everyday life, Vitamin D3 helps your body absorb and use calcium effectively while supporting healthy muscles and normal immune function.

Its nutritional contribution depends on the amount provided and overall dietary intake.

Available in

1 product

Ingredient overview

What it is

Vitamin D3, or cholecalciferol, is converted first in the liver and then in the kidneys into its biologically active form. That active form helps regulate calcium and phosphorus absorption.

  • Scientific identity: Vitamin D3; molecule: Cholecalciferol.
  • How it works: Made in skin or taken orally: Ultraviolet-B light converts a cholesterol derivative in the skin to cholecalciferol; supplements supply the same molecule directly. Hydroxylated in the liver: It is converted to 25-hydroxyvitamin D, the circulating storage form that blood tests measure.
  • Primary function: It contributes to normal bone maintenance, muscle function and immune-system activity.
  • What it supports: Vitamin D3 helps your body absorb and use calcium effectively while supporting healthy muscles and normal immune function.
  • Important consideration: Its nutritional contribution depends on the amount provided and overall dietary intake.

Formulation rationale

Why we use it

CARPEDIEM selected Vitamin D3 for a clearly defined role within a thoughtfully balanced formulation.

  • Formulation purpose: It contributes to normal bone maintenance, muscle function and immune-system activity.
  • Used in: CARPEDIEM BoneMax, CARPEDIEM MultiTeen and CARPEDIEM Women’s Bone & Daily Wellness Stack.
  • Works alongside: Vitamin D3 complements Calcium, Vitamin K2-7 and Magnesium to support comprehensive daily nutritional support.
  • Meaningful contribution: Vitamin D3 helps your body absorb and use calcium effectively while supporting healthy muscles and normal immune function. Supports normal muscle function and the mechanics of everyday movement.
  • Quality and scientific context: Its nutritional contribution depends on the amount provided and overall dietary intake. 2 ingredient-specific studies are included because the research reports a relevant benefit.

Ingredient intelligence

How it works

Less a vitamin than a hormone precursor - and it needs activating twice.

Step 01 / 04

Made or taken.

UVB light converts a cholesterol derivative in skin into cholecalciferol. A supplement supplies exactly the same molecule.

01 / 04

Molecule

Cholecalciferol

Conversion

1 microgram = 40 IU

Activated by

The liver, then the kidney

Measured as

25(OH)D - stable over weeks

Descriptive of the ingredient's established biology. Not a claim to diagnose, treat, cure or prevent any disease.

All key functions

The complete functional profile connected with this ingredient.

Supports the normal absorption and utilisation of calcium and phosphorus.

Contributes to the maintenance of healthy bones, teeth and skeletal mineral balance.

Supports normal muscle function and the mechanics of everyday movement.

Helps maintain the normal function of the body's immune-system response.

Provides cholecalciferol, a biologically recognised form of vitamin D3.

Supports the coordinated relationship between calcium intake and bone maintenance.

Helps your body absorb and use calcium effectively while supporting healthy muscles and normal immune function.

Complements Calcium and Vitamin K2-7 within a more complete, scientifically balanced daily formulation.

Selected research

Open the original paper, PubMed record or DOI page for the full publication.

01

Calcium absorptive effects of vitamin D and its major metabolites

The Journal of Clinical Endocrinology & Metabolism

Direct measurement of what vitamin D does to calcium uptake in the gut, comparing vitamin D against its metabolites. This is the experimental basis for the whole premise of pairing D3 with calcium: without adequate vitamin D status, a large share of the calcium in any supplement simply passes through unabsorbed. The calcium is only as useful as the vitamin D accompanying it.
1997
02

The vitamin D requirement in health and disease

Journal of Steroid Biochemistry and Molecular Biology

Heaney's synthesis of where vitamin D status actually needs to sit for its core job to be fully done. His conclusion: the optimisation of intestinal calcium absorption — vitamin D's canonical function — is only fully expressed once serum 25-hydroxyvitamin D reaches around 80 nmol/L, the same level at which the elevated parathyroid activity typical of ageing is minimised. It reframes vitamin D from something you either have or lack into something with a working threshold.
2005
03

Differential effects of vitamin D2 and D3 supplements on 25-hydroxyvitamin D level are dose, sex, and time dependent: a randomized controlled trial

The American Journal of Clinical Nutrition

This randomized controlled trial directly compared vitamin D2 and vitamin D3 across doses and measured changes in circulating vitamin D metabolites. It demonstrates that form, dose, sex and time can influence the biochemical response.
2017
04

Long-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over the winter months

British Journal of Nutrition

In healthy adults during winter, daily vitamin D3 maintained total circulating 25-hydroxyvitamin D more effectively than an equivalent vitamin D2 regimen. The paper supports clear identification of the vitamin D form used in a supplement.
2013

Products containing Vitamin d3

Explore the Carpediem formulations connected with this ingredient.

Complementary by function

Ingredient intelligence

How it works

Less a vitamin than a hormone precursor - and it needs activating twice.

Step 01 / 04

Made or taken.

UVB light converts a cholesterol derivative in skin into cholecalciferol. A supplement supplies exactly the same molecule.

01 04

Molecule

Cholecalciferol

Conversion

1 microgram = 40 IU

Activated by

The liver, then the kidney

Measured as

25(OH)D - stable over weeks

Descriptive of the ingredient's established biology. Not a claim to diagnose, treat, cure or prevent any disease.