Tartaric acid, raisins and gut function in healthy adults
What it found
In 13 healthy adults, both tartaric acid and sun-dried raisins softened stools and sped up gut transit time.
Raisins also raised stool weight and changed gut chemicals linked to colon cancer risk.
What they found
Studies in people
Gut transit time
Food moved through the gut faster on both diets. Transit time dropped from 42 hours at baseline to 31 hours on cream of tartar and 28 hours on raisins.
Stool softness and weight
Both diets made stools softer and easier to pass. Only raisins increased daily stool weight, from 132 g to 177 g. Cream of tartar raised it slightly to 142 g.
Bile acids in stool
Raisins lowered total bile acid concentration in stool from 1.42 mg/g to 1.09 mg/g. Cream of tartar did not change it. Lower levels are linked to reduced colon cancer risk.
Short-chain fatty acids
Raisins increased total short-chain fatty acids passed in stool over four days, from 5.6 g to 7.6 g. Cream of tartar left this unchanged at 5.6 g.
Other findings
Tartaric acid in foods
Sun-dried raisins hold 20 to 35 g of tartaric acid per kg. Fresh grapes hold 6 to 9 g per kg, and wine holds 5 to 7 g per litre.
What the authors conclude
- They say that both sun-dried raisins and tartaric acid improve gut function in healthy adults.
- The authors suggest these effects come from both the fibre and the tartaric acid found in raisins.
- They add that both foods may help lower the risk of colon cancer by changing bile acids in the gut.
How it was done
Sun-dried raisins contain fibre and tartaric acid, but scientists have not studied tartaric acid's effects on the gut much. The authors wanted to see how each part affects bowel function and gut chemicals.
Thirteen healthy adults aged 27 to 65 took part in a 9-week trial split into three 3-week cycles. They ate either 120 g of sun-dried raisins a day or 5 g of cream of tartar, which holds the same amount of tartaric acid as the raisins. Each person tried both diets after a starting period with no grape products.
What it can’t tell you
- This trial lasted only 9 weeks, so it cannot show long-term effects on gut health or cancer risk.
- With just 13 people, the results might not apply to everyone.
Who paid
- Authors work at
- Sphera Foundation, USA
The paper
- Title
- Effect of tartaric acid and dietary fibre from sun-dried raisins on colonic function and on bile acid and volatile fatty acid excretion in healthy adults
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Spiller GA, Story JA, Furumoto EJ, Chezem JC, Spiller M (2003). Effect of tartaric acid and dietary fibre from sun-dried raisins on colonic function and on bile acid and volatile fatty acid excretion in healthy adults. The British journal of nutrition. doi:10.1079/bjn2003966Free full textPubMed 13129449DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error