Riboflavin intake and constipation in US adults
What it found
In a survey of US adults, higher riboflavin intake was linked to less constipation, up to about 1.849 mg a day.
Above that level, the link was no longer significant.
What they found
Studies in people
Overall link
Higher riboflavin intake was linked to lower odds of constipation. The authors report this link remained after adjusting for many factors.
Levels of intake
The link was not a straight line. The risk of constipation fell as intake rose up to 1.849 mg a day, and this was statistically significant. Above 1.849 mg a day, the link was not statistically significant.
Who was constipated
Among the 5134 people, 1540 had constipation. The constipation group was 67.45% female and 32.55% male, so women were about twice as likely as men to report it.
Other factors
Being female and being non-Hispanic White were linked to higher constipation. Higher intakes of energy, protein, carbohydrates, total fat, saturated fats, monounsaturated fats, folate, sodium, phosphorus and potassium were also linked to more constipation. Alcohol consumption was suggested as a possible protective factor.
Subgroups
The link between riboflavin and constipation did not differ significantly across age, sex, race, marital status, BMI, alcohol use or smoking groups.
What the authors conclude
“In conclusion, an association between vitamin B2 and a reduced risk of constipation was confirmed in the study.”
Also in their conclusions
- They conclude that an association between vitamin B2 and a reduced risk of constipation was confirmed in the study.
- They advise that optimal vitamin B2 intake should be considered to promote a healthier diet and reduce the incidence of constipation.
- They say the underlying mechanisms by which vitamin B2 intake improves constipation require further investigation.
How it was done
The authors say research on the link between vitamin B2 and constipation is scarce, even though other B vitamins have been tied to gut symptoms.
They analysed data from 5134 US adults aged 20 and over in the 2009 to 2010 National Health and Nutrition Examination Survey. Food intake was recorded through 24-hour diet recalls, and constipation was based on self-reported symptoms over the past 12 months.
What it can’t tell you
- This was a cross-sectional survey, so it can show a link but not that riboflavin causes less constipation.
- Diet was estimated from 24-hour recalls, which can be misremembered, and constipation was self-reported.
- The authors note that other factors related to constipation may not have been fully accounted for.
Who paid
- Funding
- Funded by Heilongjiang Provincial Undergraduate Colleges and Universities Central Government supports the reform and development fund projects of local universities (from the PubMed record).
- Conflicts
- The authors have no conflicts of interest to disclose.
- Authors work at
- Heilongjiang University of Chinese Medicine, China; The First Affiliated Hospital of Heilongjiang University of Chinese Medicine, China
The paper
- Title
- The association between dietary vitamin B2 intake and constipation: A cross-sectional study based on NHANES 2009 to 2010
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Liu F, Liu S, Chen J, Fu J (2025). The association between dietary vitamin B2 intake and constipation: A cross-sectional study based on NHANES 2009 to 2010. Medicine. doi:10.1097/MD.0000000000045238Free full textPubMed 41088641DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error