Lettuce grown with seaweed extract and iron levels in people
What it found
Eating 100 g a day of lettuce sprayed with seaweed extract raised blood iron by about 38% in healthy adults over four weeks.
It also lowered total cholesterol by about 19% and LDL cholesterol by about 22%.
What they found
Studies in people
Blood iron rose
People who ate the sprayed lettuce saw their blood iron go up by about 38%. A measure called transferrin saturation rose by about 47%. The regular lettuce group had no changes in these markers.
Cholesterol went down
Total cholesterol fell by about 19% and LDL cholesterol dropped by about 22% in the group eating the sprayed lettuce. The iron tablet group saw similar drops. Regular lettuce did not change cholesterol levels.
No change in glucose
Fasting blood sugar, insulin and measures of insulin resistance stayed the same across all three groups after four weeks.
Iron tablet side effects
Eight of the 21 people assigned to take iron tablets quit the trial because of diarrhea or constipation. Nobody in either lettuce group dropped out.
Other findings
More iron in lettuce
Spraying lettuce with the seaweed extract raised its iron content by about 63%. Other minerals like calcium, potassium, magnesium and phosphorus stayed the same.
What the authors conclude
- They suggest that lettuce treated with this seaweed extract could help prevent iron deficiency in healthy people.
- They note it worked similarly to iron tablets but without the stomach problems.
- The authors call for larger studies lasting longer than four weeks to confirm these results.
How it was done
The authors wanted to see if spraying lettuce with a seaweed extract could boost its mineral content. They then tested whether eating that lettuce would change blood mineral levels in healthy people.
They grew lettuce with or without a seaweed spray made from Ecklonia maxima. Then 48 healthy adults, aged 24 to 65, were split into three groups for four weeks. One group ate 100 g a day of regular lettuce, one ate 100 g of the sprayed lettuce, and one took a 30 mg iron tablet daily.
What it can’t tell you
- The trial lasted only four weeks, so scientists do not yet know if these effects last over time.
- Only 48 healthy adults took part, so the results might not apply to everyone.
- People who already lack iron were not included in this study.
Who paid
- Conflicts
- Declarations. Competing interests: The authors declare no competing interests.
- Authors work at
- Experimental Zooprophylactic Institute of Sicily, Italy; University of Palermo, Italy; Euro-Mediterranean Institutes of Science and Technology (IEMEST), Italy
The paper
- Title
- Consumption of lettuce with seaweed extract biostimulant application improved iron homeostasis in a randomized interventional trial of healthy individuals
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Di Gaudio F, Vasto S, Sabatino L, et al (2025). Consumption of lettuce with seaweed extract biostimulant application improved iron homeostasis in a randomized interventional trial of healthy individuals. Scientific reports. doi:10.1038/s41598-025-91380-7Free full textPubMed 40050333DOI
Summary written 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error