Vitamin D and Hormones, Explained Without the Jargon

It behaves as a hormone rather than a nutrient, which is why excess is genuinely harmful rather than simply wasted.

Key takeaways

• Daily recommendation: 10 micrograms (400 IU)
• Upper limit without supervision: 100 micrograms (4,000 IU) a day
• Most useful single change: Take 10 micrograms daily through autumn and winter.
• Commonest mistake: High-dose products without medical supervision.
• See a doctor if any of the signs under "When to speak to a doctor" below apply to you.

The short answer

Vitamin D's role as a hormone regulating calcium, and its interaction with the parathyroid glands.

Where it fits

This is part of Thyroid And Hormones. What follows is what the guidance says, and then what that looks like in practice.

The numbers, in one place

What that means in practice

Put another way, here is what it asks of you:

• Take 10 micrograms daily through autumn and winter
• Check the dose on the bottle; products vary enormously
• Tell your GP what you take before calcium or bone tests
• Ask about testing if you have bone pain or muscle weakness

What gets people into trouble

What to watch out for:

• High-dose products without medical supervision
• Combining several supplements that each contain vitamin D
• Supplementing without advice if you have sarcoidosis or a parathyroid disorder

Where to go next

• A Q and A on Vitamin D and Hormones
• Vitamin D and Hormones: Just the Figures
• Vitamin D and Hormones — the reference entry
• The Evidence on Hormonal Contraception and Health, Without the Hype
• Hormone Replacement Therapy: Sorting the Evidence From the Noise

When to speak to a doctor

Seek medical advice for persistent thirst, frequent urination, nausea, constipation, bone pain or confusion, which can indicate high blood calcium. Speak to your GP before supplementing if you have sarcoidosis, kidney disease, a parathyroid disorder, or a history of kidney stones.

Where this comes from

• Scientific Advisory Committee on Nutrition — Vitamin D and Health
• NHS — Vitamin D

How this page was put together

Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarised or generalised beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.

Medical disclaimer

This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to a GP, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 999.