FitorexVitamin D3
A clear benefit only if you are starting from low levels.
What it is for
Correcting a deficiency (strength, bone health, immunity, mood).
How it works
A steroid hormone involved in bone health, muscle function and immunity; deficiency is very common.
Dosing
1000–2000 IU/day if you are deficient; adjust based on blood work (target 30–50 ng/ml).
When to take it
With a meal containing fat for better absorption.
Safety
Safe within the recommended range.
Side effects
Toxicity only with chronic megadoses (hypercalcaemia).
Interactions
Synergy with calcium/K2 for bone.
Contraindications
Hypercalcaemia, sarcoidosis (seek medical advice).
Who it has been studied in
Very relevant with low sun exposure, darker skin, older adults.
Frequently asked
Does it raise performance if I am already fine?
Not clearly; the benefit is in correcting a deficiency.
- Evidence tier
- B
- Quality
- Moderate
- Studies
- Many studies (heterogeneous)
- Consensus
- Correcting a deficiency yes; supplementing when replete, doubtful
- Controversy
- The optimal dose and sufficiency threshold are debated
- Reviewed
- 2024
Strength of evidence out of 5.