# Vitamin D and metabolic

3 papers in the library, strongest Moderate.

**Graded Moderate**: Observational analysis of 7,520 older adults in two national cohorts, though it cannot show cause and supplementation was tested only in rats.

## Papers (3)

- [Low Vitamin D Linked to Muscle Loss, Especially in People With Diabetes](https://usa-longevity.com/en/research/low-vitamin-d-linked-to-muscle-loss-especially-in-people-with-diabetes) · Moderate · n = 7520 · 2026 · The journal of nutrition, health & aging
- [Vitamin D Deficiency Tied to Higher Diabetes Risk in Older Adults](https://usa-longevity.com/en/research/vitamin-d-deficiency-tied-to-higher-diabetes-risk-in-older-adults) · Moderate · n = 1324 · 2026 · Journal of diabetes and metabolic disorders
- [Vitamin D Eased Fatty Liver and Blood Sugar Problems in Obese Rats](https://usa-longevity.com/en/research/vitamin-d-eased-fatty-liver-and-blood-sugar-problems-in-obese-rats) · Preliminary · 2026 · The Journal of nutritional biochemistry

## How this map is computed

A mark's size is the number of papers we hold on that pairing. It is a count, not a weighting by study design or sample size.

The fill shows the strongest grade in the cell. One Strong paper among four Preliminary ones still fills it dark, so open the cell to see the rest.

Grades and verdicts are assigned by a named person, never by counting.

An empty cell is a finding: nobody in our library has run that trial yet.

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_Canonical: https://usa-longevity.com/en/evidence/vitamin-d/metabolic · Part of Longevity Cities_