CHARACTERISTICS

Fibers are indigestible complex carbohydrates found in plants. They promote healthy bacterial growth in the colon and help bulk up the stool, making it easier to defecate. They have many health benefits: they prevent constipation, have prebiotic properties, promote satiety and reduce intestinal disorders (HOLESH & al., 2020).

A meta-analysis of 185 studies and 58 clinical trials found that fiber-rich foods reduce the risk of chronic diseases like heart disease, type 2 diabetes, colorectal cancer and obesity-related cancers as well as the mortality rate (REYNOLDS & al., 2019). Additionally, the effectiveness of fiber in managing chronic constipation was confirmed in a meta-analysis that looked at 550 clinical studies (RAO & FEDEWA, 2015).

There are two types of fiber found in plants: soluble fiber and insoluble fiber. Most foods of plant origin contain both types of fiber in varying proportions. Insoluble fibers such as cellulose and hemicellulose absorb water in the intestines, thus softening the feces and increasing their volume. As for soluble fibers such as pectin, they become viscous on contact with liquids, slowing down the absorption of lipids and carbohydrates. As a result, they lower blood cholesterol and LDL levels, defecation effort, and postprandial blood sugar. In addition, soluble fibers are fermented by bacteria in the microbiota. They have a prebiotic action and promote the production of short-chain fatty acids that support intestinal homeostasis (TOMLIN & READ, 1988 ; SCOTT & KNOWLES, 2011 ; LEVER & al., 2014).

PROPERTIES

• Gastrointestinal effects:

Prunes contain about 6 grams of fiber per 100 grams: 3 grams of hemicellulose, 2.1 grams of pectins and 0.9 grams of cellulose. They promote optimal gastrointestinal function (LEVER & al., 2014).

The laxative effects of prunes are associated with the soluble and insoluble fibers they contain, but also with the presence of sorbitol, dihydroxyphenylisatin and polyphenols (LOCKE & al., 2000). They improve intestinal transit. During constipation, the consumption of 100 grams of prunes per day increases the frequency of defecation (from 1.8 to 3.5 times per week) and improves the consistency of the stools, which become softer (ATTALURI & al., 2011).

Prunes also contain serotonin which leads to the secretion of water and electrolytes into the intestinal lumen. They have a prebiotic effect: they promote the growth of beneficial bacteria in the colon, thus contributing to the maintenance of intestinal homeostasis (SALVADOR & al., 2000).

• Antioxidant properties:

In addition to fiber, plums and prunes are an important source of antioxidants. They contain phenolic compounds, carotenoids, tocopherol and ascorbic acid. In a study carried out on 27 patients, it was shown that the consumption of 40 grams of prunes twice a day for two weeks increased the antioxidant capacity of the serum (KAPER & al., 2010).

Phenolic compounds are the main source of antioxidants in prunes (about 30%), especially chlorogenic acid (94%) (STAWEWICZ-SAPUNTZAKIS, 2013).

• Effects in cancer prevention:

Low fecal weights and slow bowel movement have been shown to be associated with an increased risk of bowel and rectal cancer (CUMMINGS & al., 1992).

In rats, the administration of 5% plums in the ration reduces the number of abnormal crypt foci by 86% following administration of the carcinogen azoxymethane. This protective effect could be explained by the fact that plums increase the activity of hepatic glutathione-S-transferase, promoting the metabolism and elimination of xenobiotics and carcinogens (BOATENG & al., 2007).

• Effects on obesity, diabetes and high blood pressure:

Prunes have a low glycemic index thanks to sorbitol: 49 for prunes and 30 for plum juice. They therefore induce limited variations in insulinaemia and glycaemia, which is beneficial in the management of diabetes and weight control (FOSTER-POWELL & al., 2002 ; LIVESEY, 2003)..

In addition, the consumption of dried fruits has been associated with a reduction in obesity and overweight. Increased consumption of chlorogenic acid is associated with a significant decrease in body weight and body fat (KEAST & JONES, 2009).

Prunes lower systolic blood pressure in hypertensive rats (NEGISHI & al., 2007).

• Effects on bone preservation:

In postmenopausal women, eating 100 grams of prunes daily for 90 days elevates serum IGF-1 levels. This hormone, which is produced by the liver in response to growth hormone stimulation, is essential for bone growth and tissue development. The consumption of prunes induces an increase in all the markers of bone formation (ARJMANDI & al., 2002).

• Anti-microbial effects:

Plums help limit the growth of many bacteria such as Listeria monocytogenes, Yersinia enterocolitica and Staphylococcus aureus in meat food samples (FUNG & THOMPSON, 2009).

It is likely that they exert an antibacterial action in vivo, particularly in the digestive and urinary systems (STAWEWICZ-SAPUNTZAKIS, 2013). In addition, they can interfere with the oral microbial flora: it has been shown that chewing prunes limits the growth of bacteria that cause cavities thanks to the sorbitol they contain (BURT, 2006).

Do not hesitate to enjoy these delicious and sun-kissed fruits.