PLUM

COMMON NAME

In Spanish-speaking countries, this plant is known as plum tree or just plum (for the fruit). Other languages of the Iberian Peninsula call it Pruner or Prunera (Catalan), Aranondo (Basque) and Ameixeira o Ciroleira (Galician and Portuguese). From a more global perspective, the names received are: prune (dried plum), Plum, Asian Plum, European Plum, French Plum, Japanese Plum, Damson Plum, Wild Plum and Yellow Plum, among many other cultivars.

TAXONOMICAL NAME

The most common and consumed species are Prunus domestica L. (European plum) and Prunus salicina (Japanese plum). It is part of the Rosaceae taxonomical family. Prunes (or dried plums) are almost exclusively made from Prunus domestica.

DESCRIPTION

Plum tree is an extensive cultivar that produces a pulpy fruit that is eaten regularly worldwide. The botanical genre includes more than 40 species, but medicinal benefits have been mainly studied in specific cultivars. Plum can be eaten fresh, as juice or puree or even dried (which are usually known as prunes). Prunes are made by drying the fruit at high temperatures (generally between 60 and 90 °C). This process keeps the majority of phenolic compounds but destroys almost all anthocyanidins. This fruit mainly stands out as a source of macronutrients, vitamins and fibre.

PART USED

At therapeutic and nutritional levels, the vegetable drug is made of the fruit (skin and pulp) from Prunus domestica L. and similar species, both fresh and dried. Then, from the cotyledon of the seeds (the inside of the pit), an essential oil is extracted and, then, used as an almond oil replacement.

ACTIVE PRINCIPLES

Plum concentrates a high quantity of bioactive constituents, among which we can find:

• Dietary fibre (6-7%): Soluble and non-soluble fibres: pectin (up to 1% of the weight), cellulose and hemicellulose.
• Carbohydrates and sugar alcohols: High concentrations of sorbitol (10-15%), inositol and fructans.
• Phenolic compounds: It is an exceptional source of antioxidants. It contains hydroxycinnamic acids (chlorogenic, neochlorogenic, feluric, caffeic, protocatechuic and p-coumaric acid), flavonoids (quercetin, kaempferol), anthocyanosides and many types of carotenoids such as beta-carotene, lutein, zeaxanthin and β-cryptoxanthin.
• Vitamins and minerals: It is rich in vitamins A, B1, B2, C and E, as well as key minerals, especially potassium, magnesium, iron, copper, manganese, zinc and boron (5 prunes supply ~1.1 mg of boron, which is essential for bone health).
• Organic acids: Malic acid and citric acid.

PHARMACOLOGICAL ACTION

• Laxative and prebiotic effects: The high content in fibre and sorbitol provides a mechanical laxative effect, which can increase faecal mass and retain water in the colon. Moreover, it also possesses a regenerative action over the bowel’s bacterial flora, since fibres act as a prebiotic substrate that increases healthy populations (Bifidobacterium, Lactobacillus, Lachnospiraceae family) and decreases pathogens (Escherichia coli, Clostridium perfringens). All of this promotes the fermentation and production of short-chain fatty acids.
• Bone protective activity: Phenolic and mineral compounds like boron stimulate bone growth, increase the bone formation and inhibit resorption and formation of osteoclasts. Phenols supress cellular inflammatory mediators.
• Lipid and cardiovascular profile: The fibrous and phenolic matrix contributes to decreasing fat and carbohydrates absorption, which reduces lipogenesis and promotes a fat lowering effect; specially reducing LDL cholesterol. Furthermore, the content in potassium contributes to regulate blood pressure of bodily fluids.
• Antioxidant, immune and anti-cancer effects: It shows a general antioxidant activity mediated by compounds like cryptoxanthin and an increase of antioxidant enzyme activity in the body. Preliminary studies suggest that fibre and antioxidants reduce the production of procarcinogenic bacteria in the colon and can promote apoptosis in various cancer cell lines, acting as a chemo-preventive agent. Activity on inflammatory arthritis models has also been described, regulating immune response pathways against TNF.

INDICATIONS

• Functional or chronic constipation: The European Food Safety Authority (EFSA) acknowledges the use of plum to “maintain a normal bowel function”. It is highly effective when taken whole, as juice or puree. These preparations surpass regular food supplement in multiple measuring. For instance, it is more effective than psyllium to soften stools and increase defecatory frequency.
• Prevention of bone loss (osteopenia / osteoporosis): According to clinical evidence, plum is indicated as a coadjutant treatment to prevent the loss of bone mineral density in postmenopausal adults and to lower the risk of bone fragility.
• Metabolic health and dyslipidaemias (traditional): Traditionally used to reduce or control cholesterol-related problems, providing potential reduction in low-density lipoproteins.

CONTRAINDICATIONS

• Hypersensitivity: Known allergies to plum.
• Bowel obstruction: Patients affected by severe intestinal obstruction.
• Inflammatory disorders or frequent diarrhoea: Completely contraindicated in cased of irritable bowel disease, diverticulitis, Crohn’s disease or ulcerative colitis, due to the stimulating effect on bowel transit.

PRECAUTIONS

• Pregnancy and breastfeeding: There is no rigorous information regarding the use of dosages highly over those regularly found in food. Do not take medicinal quantities during these stages.
• Choking risk: Little children and elderly people eating the whole fruit, with no precaution, reported cases of small bowel obstruction, ileostomy or occasional oesophagus perforation, caused by the accidental ingestion of the pit.
• Theoretical interaction with antiplatelet drugs: In vitro, plum juice inhibits platelet aggregation and increases coagulation times. Precautions must be taken when taking anticoagulant and anti-platelet drugs or plants, since, theoretically, the chances of presenting bleeding or bruises increase.

SIDE EFFECTS AND TOXICITY

Generally, oral consumption of plum is qualified as safe, with excellent tolerability. This data applies to medicinal levels of up to 100 g a day for long periods of time. No diagnosable systemic toxicity was reported. Observed side effects are generally caused in the gastrointestinal area and frequently report cases of excessive flatulence, abdominal distension and mild diarrhoea in sensitive population or high doses. Furthermore, allergic reactions caused by cross sensitivity with other foods of the same botanical family (like peach, cherries or apricot). Due to the high quantity of fibre in the dried matrix, it may cause malabsorption of concomitant drugs. This is why it is imperative to separate the intake of prunes and supplements, vitamins or medicines by at least 30 minutes.

STUDIES

Many clinical studies and metanalysis support the properties of plum.

• Trials made on constipation: A relevant randomised and double-blind crossover study (Attaluri et al., 2011) exposed 40 test subjects with constipation to a daily intake of 100 g of prunes versus 6 g psyllium fibres. Plum demonstrated a notable and statistically significant improvement of spontaneous complex defecation, as well as stool consistency, when compared to psyllium.
• Research on bone mineral density:   The uninterrupted administration of 50-100 daily grams of prune during time periods of 6 to 12 months to groups of osteopenic menopausal women and risk population of bone fracture (studies of Hooshmand S. et al.), achieved to notably mitigate bone loss, preserve thickness in critical bones like femur or ulna and also, to regulate good metabolic biomarkers of the bone tissue against food controls.
• Microbiome and cardiovascular risk: The latest metanalysis and observational studies assessed evident reductions in total levels of circulating lipoproteins and the mitigation of liver enzymes after dietary intervention based on plum extracts. At the same time, it also notably increased microbiota (such as Lachnospiraceae taxa).

BIBLIOGRAPHY

1. Askarpour M, Ghalandari H, Setayesh L, Ghaedi E. Plum supplementation and lipid profile: a systematic review and meta-analysis of randomised controlled trials. J Nutr Sci. 2023; 12: e6.
2. Attaluri A, Donahoe R, Valestin J, Brown K, Rao SS. Randomised clinical trial: dried plums (prunes) vs. psyllium for constipation. Aliment Pharmacol Ther. 2011; 33 (7): 822-8.
3. Hooshmand S, Kern M, Metti D, Shamloufard P, Chai SC, Johnson SA, et al. The effect of two doses of dried plum on bone density and bone biomarkers in osteopenicpostmenopausal women: a randomized, controlled trial. Osteoporos Int. 2016; 27 (7): 2271-2279.
4. Igwe EO, Charlton KE. A systematic review on the health effects of plums (Prunus domestica and Prunus salicina). Phytother Res. 2016; 30 (5): 701-31.
5. Stacewicz-Sapuntzakis M. Dried plums and their products: composition and health effects. An updated review. Crit Rev Food Sci Nutr. 2013; 53: 1277-1302.