---
type: source
title: "Frontiers in Nutrition 2025: Cross-Sectional Study of GLP-1 Users — Near-Universal Vitamin D Shortfall, 64% Iron-Deficient, 72% Calcium-Deficient"
author: "Frontiers in Nutrition (10.3389/fnut.2025.1566498)"
url: https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1566498/full
date: 2025-03-01
domain: health
secondary_domains: []
format: research-paper
status: unprocessed
priority: medium
tags: [GLP-1, nutrition, micronutrients, vitamin-D, iron, calcium, protein, cross-sectional, DRI, dietary-reference-intake]
---

## Content

Cross-sectional study examining nutrient intake during GLP-1 receptor agonist use.

**Study design:**
- n = 69 participants (adults using GLP-1RA for at least 1 month)
- Participants completed 3-day food records + online survey questionnaires
- Compared intake against Dietary Reference Intakes (DRI)

**Key findings:**
- **Vitamin D**: Only 1.4% of participants met 100% of the DRI. Mean intake 4 μg/day vs. national average of 19 μg/day — 79% below national baseline.
- **Iron**: 64% consumed below the Estimated Average Requirement (EAR); highest prevalence among women and individuals undergoing aggressive caloric restriction.
- **Calcium**: 72% consumed below the RDA.
- **Protein**: 58% did not meet recommended targets (1.2–1.6 g/kg/day during weight loss per multi-society advisory).

**Bottom line stated by authors:** "Participants on a GLP-1RA are not meeting the Dietary Reference Intakes for several vital nutrients through their diet."

**Limitation:** Small sample (n=69), self-selected, cross-sectional design. Not representative of Medicaid or food-insecure populations — likely skews toward commercially insured, internet-accessible patients. No control group.

## Agent Notes

**Why this matters:** Primary data study (vs. cohort database claims study) with dietary record methodology. The 1.4% vitamin D DRI compliance figure is from this study and is the most striking specific datum in the GLP-1 nutritional literature. Despite the small n, the convergence with Urbina 2026 (n=480,825) gives confidence this isn't a sample artifact.

**What surprised me:** The 1.4% vitamin D DRI compliance. This is not a marginal shortfall — it means 98.6% of GLP-1 users in this sample were not meeting even the recommended dietary intake for vitamin D, a nutrient already deficient in ~40% of the general US population.

**What I expected but didn't find:** Any stratification by food security status. The study participants likely have commercial insurance and internet access (required to complete online survey). This means the deficiency rates found here may be UNDERESTIMATES for food-insecure populations, who start from a worse nutritional baseline.

**KB connections:**
- Consistent with and supportive of Urbina 2026 narrative review (`2026-01-xx-urbina-clinical-obesity-glp1-micronutrient-narrative-review.md`)
- The 1.4% vitamin D DRI figure is specifically useful for claim writing — it's a concrete data point

**Extraction hints:**
- Use as supporting evidence for the broader nutritional deficiency claim, not as a standalone claim
- The 1.4% vitamin D DRI compliance is the single most quotable datum from this source
- Note sample limitation: n=69, likely commercially insured, online-accessible patients

**Context:** Frontiers in Nutrition is a peer-reviewed open-access journal. Study methodology (3-day food record) is considered more reliable than dietary recall alone but has known limitations (underreporting, short capture window).

## Curator Notes (structured handoff for extractor)

PRIMARY CONNECTION: `2026-01-xx-urbina-clinical-obesity-glp1-micronutrient-narrative-review.md` (supporting data point)
WHY ARCHIVED: The 1.4% vitamin D DRI compliance figure from dietary records is the most concrete datum for the nutritional deficiency claim. Small study but converges with larger systematic evidence.
EXTRACTION HINT: Use as supporting evidence, not primary source. Archive for the 1.4% vitamin D figure specifically.
