Can prunes modify gut health?

Chiu et al.¹ demonstrated the modulatory effect of prune essence concentrate (PEC) on gut microflora and other health benefits including reduced levels of total cholesterol and LDL-c, and increased antioxidant activity.

To study the effects of PEC, Chiu and colleagues¹ conducted a study on 60 mildly hypercholesterolemic healthy adults, who were divided into 3 groups, namely, PEC I (intake of 50 ml PEC/day), PEC II (intake of 100 ml PEC/day), and placebo (intake of 50 ml simulated prune drink) for 4 weeks and a 2-week follow-up (without any intervention).

The results were positive for gastrointestinal function after the consumption of both PEC I and II for 4 weeks, which showed a selective increase in beneficial gut microflora, Bifidobacterium species (1.18 and 1.19 times) and Lactobacillus species (1.07 and 1.16 times) along with a decrease in harmful bacteria, Clostridium perfringens (5.97% and 8.35%) and Escherichia coli (6.25% and 9.38%). Furthermore, there was also a reduction in total cholesterol (5.90% and 6.99%) and LDL-c (6.68% and 6.53%) levels with an increased level of antioxidant activity.

Interestingly, in the follow-up period when PEC consumption was discontinued, there was a reversal of all beneficial effects including a decrease in Bifidobacterium and Lactobacillus species, an increase in Clostridium perfringens and Escherichia coli species, and mild elevation of TC and LDL-c levels.

Another recent research article published in Clinical Nutrition showed increased stool frequency (p= 0.023), stool weight (p= 0.026) and increase in Bifidobacteria count (p = 0.046) in a 4-week intervention cohort supplemented with prunes (80 g/day and 120 g/day)².

Gut health plays a critical role in the overall health of an individual, since increased number of beneficial bacteria in the intestines promotes digestion, transforms bile acids, produces short-chain fatty acids and vitamins, which could help digest and absorb nutrients, provide energy, prevent gut mucosal injury, lower cholesterol and ammonia levels, prevents growth of harmful microbes, stimulates immunity, and prevent allergy and inflammatory bowel disease³. 

Foods are important for the maintenance of gut health. Prebiotics are dietary foods that are non-digestible and selectively fermented, which stimulate the growth of specific bacteria in gut microbiota increasing host health benefits⁴. Inulin-type fructans and galactooligosaccharides are two main prebiotics that are dietary carbohydrates; they are known to promote the growth of bifidobacteria, lactobacilli and bacteroides⁵.

PEC (Prune Essence) is rich in dietary fiber (pectin), oligosaccharides (inulin, xylooligosaccharides), sorbitol, fructose and phenolic compounds1; the presence of oligosaccharides may render it prebiotic activity.

Prunes (dried plums) promote gut health that is attributed to their high dietary fiber, sorbitol and phenolic chlorogenic acids. They are known to increase stool frequency, stool consistency, and stool mass, conferring them an excellent laxative. Prunes at 100 g/day are considered superior to psyllium in constipated individuals⁶. 

Although, phenolic chlorogenic acid (present in prunes and prune essence) is considered to possess prebiotic effect in in vitro studies⁷; its effect in humans is yet to be determined. 

The studies by Chiu et al.¹and Lever et al.² are the first few studies that suggest promising prebiotic effect of prunes and prune essence, but other studies are warranted to further determine prunes as prebiotics and the active ingredient in them that confers them their prebiotic effect.