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Longevity supplements › NMN and Aging › Studies

Randomized trial · measured other health measures

A 32-day trial of niacin-related nutrients in 14 older adults: no clear muscle change

Connell and colleagues · The Journal of nutrition · 2021

Original title: NAD+-Precursor Supplementation With L-Tryptophan, Nicotinic Acid, and Nicotinamide Does Not Affect Mitochondrial Function or Skeletal Muscle Function in Physically Compromised Older Adults.

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What the study found

No difference

Muscle NAD+ did not differ from control. Muscle energy-making breathing rates did not improve (ADP-stimulated P = 0.716; maximal P = 0.495), nor did exercise efficiency (P = 0.342).

The study at a glance

Type of study
Randomized trial
Who or what was studied
14 people · Older adults living at home with weak physical function, average age 72.9
What was tested
Tryptophan, nicotinic acid and nicotinamide (207.5 mg niacin equivalents a day) for 32 days, vs a control product
What it measured
Several kinds of outcomes
Daily amount
207.5 mg a day
How long
4.6 weeks
Trial registration
NCT03310034
Who has a stake
No disclosure in PubMed
No disclosure in PubMed.
Journal
The Journal of nutrition, 2021
Source
PubMed record 34191033. This page is based on the abstract only.

How much this study counts

  • ✓Randomized: people were put into groups by chance, so the groups start out alike.
  • –Small: 14 people. Small trials can miss real effects or find chance ones.
  • –Short: 4.6 weeks. Longer-term effects are unknown.
  • •Measured several kinds of outcomes.
  • •The PubMed record has no conflict-of-interest statement.
  • •Summarized from the PubMed abstract only. The full paper may hold details the abstract leaves out.

✓ Strength– Limit• Note

These points come from fixed rules about the type of study, its size and length, what it measured, and who has a stake. Every study on Digestery gets the same rules.

Where this study sits

Each dot is one on-topic paper on this question. Steps near the top answer the question more directly.

↑ Stronger evidence

  1. Trials in people: aging and age-related decline

    0

    Not done yet. This is the step that would answer the question.

  2. Trials in people: other measures

    9

    3 benefit, 2 mixed, 4 no difference

    ↑ This study is the ringed dot

  3. Trials in people: lab tests or safety

    7

    4 benefit, 1 mixed, 2 no difference

  4. Population studies

    0

    None among the papers we read.

  5. Blood levels and genes

    0

    None among the papers we read.

  6. Animals

    6

    5 benefit, 1 mixed

↓ Weaker evidence

  • Points to benefit
  • Mixed
  • No difference
  • No direction
  • Points to harm

How it fits with the other research

The short answer to “Does NMN slow aging?”

Not shown in people so far.

Confidence: very low. Based on 29 on-topic papers.

Read the full answer

Of the other 8 papers on the same step: 3 benefit, 2 mixed, 3 no difference. This one found no difference.

Other papers on the same step

See all 29 studies on this question

How this page was made

Label

First read of the abstract
Claude Sonnet
Independent second read
Claude Haiku
Differences settled
The reviewer corrected 1 field after reading the abstract. Claude Opus 5.5.
Headline
Claude Sonnet, from the checked study record. A script checked its numbers and wording.
Numbers
Checked against the abstract by a script
“How much this study counts”
Fixed rules, the same for every study
Source check by a person
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