Barley melanoidins and their possible health effects
What it found
Barley melanoidins, the brown compounds formed when barley is roasted or brewed, have been linked to antioxidant, gut and other effects in lab tests and in mice.
Most of the evidence comes from cells, test tubes and animals, not people.
What they found
Animal and lab studies
Antioxidant activity in lab tests
In lab tests, melanoidins scavenge free radicals, have reducing power and bind metal ions. Black malt showed higher reducing power and radical scavenging capacity than melano 80 and pale malt.
Protecting DNA
Beer melanoidins are reported to protect cells from oxidative damage to DNA. In beer, levels of 8-OHdG, a marker of DNA damage, were negatively correlated with melanoidin concentration, especially in dark beer.
Blocking lipid peroxidation
Melanoidins can bind metals during digestion, which inhibits lipid peroxidation, and they can bind heme from red meat and limit its absorption in the gut. These effects are described from lab and digestion studies.
Gut bacteria in mice
In mice fed melanoidin-rich malted barley for 3 weeks, gut bacteria clustered by diet. Bacteroidetes responded within 7 days, while Bifidobacterium and Akkermansia increased later in the study.
Studies in people and animals
Melanoidins as fiber
Because melanoidins are poorly digested and gut bacteria can use them, they have been proposed to act like dietary fiber with possible prebiotic effects. In lab fermentation tests, bread melanoidins stimulated Bifidobacteria, but responses varied between people.
Possible downsides
Maillard reaction products have been linked to reduced protein digestibility and lower availability of some minerals in rats. High dietary carboxymethyl lysine is associated with diabetes and cardiovascular diseases, and acrylamide with tumors.
Other findings
What melanoidins are
Melanoidins are brown, high molecular weight compounds formed as the final products of the Maillard reaction, which happens when sugars react with amino acids and peptides at high temperatures. Food processing temperatures range from 90 to 220°C.
What the authors conclude
“Therefore, comprehensive studies are required to understand better the chemical structure and specific health-benefiting properties of food melanoidins.”
Also in their conclusions
- They say comprehensive studies are required to better understand the chemical structure and specific health-benefiting properties of food melanoidins.
- They state that barley as a source of melanoidins needs more attention because it can be grown in marginal areas with low input and its use in malting and brewing produces many by-products containing melanoidins.
- They advise that more research is warranted to explore the chemical properties of barley melanoidins and their corresponding health benefits.
How it was done
The authors say food melanoidins are still rather understudied despite their potential antioxidant, antimicrobial and prebiotic properties. They also note that barley is economically important through beer production and increasingly as a functional food, so more research into barley melanoidins is warranted.
They gathered published research on melanoidins from barley, malt and beer, covering how these compounds form during roasting and brewing and what has been measured in lab tests, animals and people. They also describe their own 3-week mouse study in which mice were fed malted barley with increasing amounts of melanoidin-rich malt.
What it can’t tell you
- Most of the evidence comes from lab tests and mice, so it cannot show what barley melanoidins do in people.
- The mouse study lasted only 3 weeks, so it cannot show long-term effects.
- The review cannot show whether melanoidins cause any health outcome, only what has been measured or linked in the studies it covers.
Who paid
- Conflicts
- The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
- Authors work at
- Maharshi Dayanand University, India; Washington State University, United States
The paper
- Title
- Barley Melanoidins: Key Dietary Compounds With Potential Health Benefits
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Sharma JK, Sihmar M, Santal AR, Prager L, Carbonero F, Singh NP (2021). Barley Melanoidins: Key Dietary Compounds With Potential Health Benefits. Frontiers in nutrition. doi:10.3389/fnut.2021.708194Free full textPubMed 34651008DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error