# Follow the finding back to its source

A linked source

A place to check what a finding says, and how far it goes.

These are the papers and official pages linked across the guide. I’ve kept a short note beside each so you can find the one you need. Open the source when you want the details; the notes are a way in, not the whole story.

## Energy and cell signals

[MOTS-c and metabolic regulation in mice](https://pubmed.ncbi.nlm.nih.gov/25738459/)

The first MOTS-c study in cells and mice. Treated mice on a high-fat diet gained less weight and handled sugar better.

[FDA review of MOTS-c](https://www.fda.gov/media/193347/download)

FDA found no published human treatment studies and gaps in basic safety testing. A promising mechanism leaves those questions open.

[Registered MOTS-c study in adults with prediabetes](https://clinicaltrials.gov/study/NCT07505745)

A plan to test MOTS-c in adults with prediabetes, a blood-sugar condition, and extra weight. The record supplies no results.

[NAD+ in human health and disease](https://pubmed.ncbi.nlm.nih.gov/34041853/)

NAD+, nicotinamide adenine dinucleotide, helps cells handle energy. This biological role doesn’t establish that giving more makes someone less tired.

[NMN and muscle insulin sensitivity](https://pubmed.ncbi.nlm.nih.gov/33888596/)

NMN is a building block for NAD+. Muscle responded better to insulin, but body composition and longer-term blood sugar stayed unchanged.

[Human studies of NAD+ precursors](https://pubmed.ncbi.nlm.nih.gov/37068054/)

Studies of NAD+ precursors, the materials used to make it. Biological measurements changed more consistently than functional outcomes; follow-up was limited.

## Immune signals and the gut

[FDA review of thymosin alpha-1](https://www.fda.gov/media/183892/download)

FDA’s 2024 review found too little evidence for the uses it checked. It also covers injection-site reactions and quality concerns.

[KPV uptake and intestinal inflammation](https://pubmed.ncbi.nlm.nih.gov/18061177/)

KPV research in gut-lining cells grown in a dish, alongside mouse bowel-inflammation experiments. This isn’t a treatment trial in people.

[FDA review of KPV](https://www.fda.gov/media/193346/download)

FDA found no human evidence to judge benefit or side effects. KPV’s exact targets also remained uncertain.

## Brain signals and sleep

[Semax and resting brain activity](https://pubmed.ncbi.nlm.nih.gov/30225715/)

A small Semax brain-scan study in healthy volunteers. Better everyday memory and focus were not established.

[FDA review of Semax](https://www.fda.gov/media/193348/download)

FDA describes limited clinical evidence, incomplete safety reporting and a bleeding concern from rats, rather than a measured human effect.

[A controlled DSIP study in chronic insomnia](https://pubmed.ncbi.nlm.nih.gov/1299794/)

An older insomnia trial. The authors called the sleep effects modest and questioned the practical benefit of short-term treatment.

[The unresolved biology of DSIP](https://pubmed.ncbi.nlm.nih.gov/16539679/)

Delta sleep-inducing peptide, or DSIP, still had a weakly established sleep link and unresolved biology.

## Access and the care conversation

[FDA safety concerns and withdrawn nominations](https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks)

FDA’s page current as of April 22, 2026 lists the five peptides discussed here as nominated but withdrawn. That isn’t clearance or compounding approval; individual withdrawal dates aren’t given.

[FDA questions and answers about compounding](https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers)

Compounded drugs are not FDA-approved. Before these drugs reach the market, FDA has not reviewed whether they work, are safe or meet quality standards. A prescription doesn’t change that.

[HHS guidance on telehealth licensure](https://telehealth.hhs.gov/licensure/getting-started-licensure)

U.S. Department of Health and Human Services guidance: clinicians need to meet licensing rules where they are and be legally allowed to practise where you are.