In a recent narrative review published within the Nutrients Journal, researchers retrieved articles from multiple sources, including PubMed, MedLine, and Web of Science, discussing the results of dried fruits on overall gastrointestinal (GI) health, including gut microbiota, heart problems (CVD) risk, type two diabetes (T2D), bone health, and eating regimen quality.

More importantly, the researchers discussed the mechanisms possibly involved in these processes and highlighted dried fruits’ phytochemical composition and their bioavailability and accessibility.

Study: Dried Fruits: Bioactives, Effects on Gut Microbiota, and Possible Health Advantages—An Update. Image Credit:5PH/Shutterstock.com

Background

On account of their high fiber content and antioxidant properties, dried fruits have multiple health advantages. As well as, they’re shelf-stable, which makes them a convenient substitute for fresh fruits. Dried fruits contain several bioactive compounds broadly classified as phytochemicals, including phenolics, carotenoids, stilbenes, chalcones/dihydrochalcones, phytoestrogens, and flavonoids.

More recently, studies have found associations between dried fruit consumption on gut microbiota composition and functionality. Gut microbiota contributes to metabolic health; thus, identifying dietary strategies promoting metabolic health through modification of the gut microbial population needs to be a priority.

As well as, there’s a necessity for an in-depth evaluation of the biological activity of the bioactive compounds in dried fruits and their bioaccessibility and bioavailability.

Concerning the study

In the current narrative review, researchers restricted their literature search to articles published from 2000 onward to enhance contemporary relevance. They covered articles on primarily seven topics, for example, the phytochemical composition of ceaselessly consumed dried fruits.

Nonetheless, they examined chosen articles intimately to compile evidence from in vivo and in vitro studies on the results of commonly consumed dried fruits on cardiometabolic and GI health.

This helped the researchers provide updates on the phytochemical composition of dried fruits and mechanisms possibly involved of their biological effects. Finally, they made dried fruit consumption recommendations based on the reviewed evidence.

Effect of dried fruits composition

Alasalvar et al. showed that dried fruits have diverse phenolic profiles. Nonetheless, the precise phenolic profiles of dried apples, peaches, and pears are unknown. They documented that nine dried fruits, viz., apples, cranberries, apricots, dates, peaches, pears, figs, prunes, and raisins, comprised phenolic compounds, resembling anthocyanins, flavonols, flavones, phenolic acids, etc.

For example, carotenoids (resembling β-carotene) are plant pigments liable for shiny yellow, red, and orange hues in lots of vegetables and fruits and are abundant in all dried fruits except seedless raisins, though in variable quantities.

Apricots are the richest source of β-carotene, followed by peaches and prunes, with 2,163, 1,074, and 394μg/100 g of β-carotene in these dried fruits, respectively. Apricots, dates, prunes, and raisins also contain phytoestrogens, that are absent in dried apples, figs, peaches, and cranberries.

Studies should aim to comprehensively analyze different phenolic compound classes, viz., carotenoids and phytoestrogens in various dried fruits. As well as, consumption of 20 to 30 grams of dried fruits per/day could provide 10 to 16% of the beneficial day by day fiber intake, depending on the chosen dried fruit.

The oxygen radical absorbance capability (ORAC) of dried fruits is comparatively high, various with type and variety. For instance, golden seedless raisins have the very best ORAC value of 10,450 µmol Trolox equivalents (TE)/100 g.

Bioaccessibility and bioavailability of compounds in dried fruits

Several models mimicking human in vitro GI digestion processes (e.g., oral or salivary digestion and gastric digestion) have investigated the bioaccessibility and bioavailability of compounds in dried fruits cost-effectively.

When phytochemicals and micronutrients in food are released within the GI tract, then they change into bioavailable for absorption to exert health effects.

The researchers observed the very best bioaccessibility of phenolics in prunes and the bottom in dates and cranberries in a recent study by Scrob et al. Total sugar content increased after in vitro digestion of coconuts, raisins, and dates but decreased for cranberries, prunes, and bananas. Nonetheless, in vitro digestion increased the antioxidant activity of most dried fruits.

One other study by Ma et al. investigated the biological activities of kiwifruits, including dried slices under simulated GI in vitro digestion. Though dried kiwi slices and jams had the very best quantity of minerals per unit weight than other forms, dried slices showed the bottom biological activity in comparison with raw fruit, juice, yogurt, wine, and jelly.

Effect of dried fruits on gut health, and their dietary recommendations

Data are scarce on the results of dried fruits on metabolite production within the gut and their functions. Nonetheless, this is for certain that the consumption of dried fruits modulates the gut microbiota to influence health.

More than likely, phytochemicals in dried fruits undergo substantial biotransformation by gut microbiota to supply metabolites that influence health. Future mechanistic studies should address these questions.

Suboptimal fruit intake is a key contributor to CVDs, T2D, and neoplasms. So a healthy eating regimen comprising five portions of fruit and vegetables per day, excluding starchy fruits, is the premise for current dietary recommendations by the World Health Organization (WHO). The present dietary guidelines for Americans also recommend 4 servings of fruit per day, where one-fourth of a cup of dried fruits equals half a cup of fruit.

Unfortunately, fruit consumption in most countries, including some European countries and america of America, falls in need of current dietary recommendations for fruit (20 to 30 grams per day) per the Global Burden of Disease Study 2017.

Mechanisms driving dried fruits-related health advantages

Human studies have found that dried fruits have a low-to-moderate glycemic index on account of their high mineral content, especially potassium and magnesium, and increased fiber content, in addition to high levels of antioxidants and phytochemicals.

Thus, frequent consumption of dried fruits advantages cardiovascular, gut microbiota, and bone health. Strikingly, their consumption may additionally offer therapeutic advantages. Nonetheless, how dried fruits reduce the severity of chronic metabolic diseases warrants further in-depth exploration.

A recent study evidenced that prunes prevent and reverse bone loss in postmenopausal women and potentially in men. Phytochemicals, resembling chlorogenic acid and catechin, have osteoprotective effects; nevertheless, the mechanisms governing these effects remain unknown.

Epidemiological and clinical evidence for health advantages of dried fruits

Few epidemiological studies reported favorable associations between dried fruit and CVDs, T2D, and body weight but didn’t fetch consistent results. Also, the general eating regimen quality of the participants confounded the observed associations.

More extensive adjustments for dietary and lifestyle aspects might help future epidemiological studies investigating dried fruit consumption. Also, those studies should include populations that usually devour greater dried fruits to fetch stronger evidence of associations between dried fruit intake and health advantages.

There may be mixed evidence regarding the effect of dried fruit consumption on CVD risk aspects. Several clinical studies have shown their consumption reduces cholesterol and blood pressure without harming glycemic control. Additional randomized controlled trials accounting for the potential confounding effect of body weight are needed to verify the cardiovascular advantages of dried fruit consumption.

Five clinical trials performed in postmenopausal women have shown that an intake of fifty to 100 grams of prunes day by day for 3 to 12 months has some osteoprotective effects. The opposite 4 clinical trials showed the potential anti-inflammatory effects of dried fruits and their useful effects on bone formation and resorption markers.

One other study by Hooshmand et al. showed eating 100g of prunes per day increased bone mineral density (BMD) of the ulna and spine in a yr in comparison with 75g of dried apple.

Conclusions

Though an emerging area of research, current evidence on the results of dried fruits on the human microbiome, bone health, eating regimen quality, and CVD risk is scarce and warrants further investigation. Studies have adequately investigated the phytochemical profiles of various dried fruits; nevertheless, an understanding of their bioaccessibility and bioavailability is restricted.

The encouraging results from the studies elucidating the advantages of dried fruits, fresh fruits, and juices justify further research. Additional research could also provide a greater understanding of the biological effects of dried fruits on major chronic diseases and their underlying biological mechanisms to tell future dietary guidance for dried fruits.