Magnesium for Constipation
Magnesium, in osmotic salt forms such as magnesium oxide, citrate, or hydroxide, works as an effective short-term treatment for occasional and chronic constipation. Note that "calming" forms like magnesium glycinate are not laxatives, and people with kidney impairment should avoid it without medical supervision.
Why this grade7-layer evidence engine
This earns a Moderate (A) grade because both controlled trials and a meta-analysis show a clear, consistent benefit, even though the evidence base is modest in size. A double-blind RCT (PMID 31587548) found 1.5 g/day magnesium oxide produced a 70.6% response rate versus 25.0% on placebo (p=0.015), and a high-quality meta-analysis (PMID 37243443, n=787) reported roughly 3.72 extra bowel movements per week and softer stools (Bristol +1.14). A pediatric RCT (PMID 31952280) and opioid-induced constipation studies (PMID 35565243, PMID 38452708) add support, though magnesium oxide was less potent than newer agents like naldemedine for opioid cases.
Clinical authorities reinforce this. Cleveland Clinic calls magnesium 'an effective way to treat mild to moderate constipation,' while Mayo Clinic and Harvard Health describe magnesium citrate and oxide as osmotic laxatives that draw water into the bowel. In 2023 the AGA/ACG gastroenterology panel formally suggested magnesium oxide for chronic idiopathic constipation, the first time it appeared in an official guideline.
It stops short of the top tier for honest reasons. The pivotal RCT was small (n=33), and the guideline rates its own recommendation as conditional with very low certainty of evidence. Drug regulators (FDA, EFSA, WHO) classify magnesium only as a nutrient or treat it for unrelated uses, not constipation. The benefit is also form-specific (oxide, citrate, hydroxide work; glycinate does not), it is meant for short-term use rather than long-term reliance, and high doses or kidney impairment raise the risk of diarrhea and dangerous hypermagnesemia.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.76
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status