Bowel function of postmenopausal women: Effects of daily consumption of dried plum

ABSTRACT

Calcium and vitamin D were provided to 48 postmenopausal women for 6 months and randomly assigned into control, 50 g/d dried plum, or 100 g/d dried plum groups to examine dried plum influences on bowel habits. No adverse effects of dried plum were detected, whereas pain and constipation ratings increased (p<0.05) in the control group. Pain was higher (p=0.049) at 6 months for control versus 50 g/d dried plum and lower (p=0.042) at 3 months for 100 g/d dried plum versus 50 g/d. Constipation ratings were higher for control than 100 g/d dried plum at 6 months. Dried plum in the dose of 50 or 100 g per day did not produce adverse effect and may decrease discomfort of bowel movements.

KEYWORDS:

• Bowel movement
• Fibre
• Prune
• Postmenopausal women
• Dried plum

Introduction

It has been reported that the prevalence of constipation among elderly patients is 50% for those living in the community ^[1,2] and 74% for nursing home residents.^[1–3] The prevalence of constipation increases with age, particularly in those over the age of 65 years.^[4] Likewise, elderly women are two to three times more likely to report constipation than elderly men.^[1,4] Although increased dietary fibre intake has been recommended as a primary and effective treatment for constipation,^[5–7] there is still insufficient evidence to support the efficacy of naturally occurring food-based dietary fibre for the treatment of constipation.^[4,8] A survey study ^[9] in the US demonstrated that almost half of the 383 people with chronic constipation were not completely satisfied with taking medication to manage their constipation. Therefore, because of poor satisfaction with laxative and other common medication to manage the constipation,^[10] the public demand for functional foods that are beneficial for gastrointestinal (GI) health is considerable.^[11]

The daily use of dried plum and prune juice has been demonstrated as an acceptable and effective treatment for stool softening and immediate relief of constipation symptoms ^[12–14] In one study, dried plum increased bowel movement frequency and improved stool consistency ratings in comparison to psyllium.^[12] The authors speculated that fibre, phenolic compounds (184 mg/100 g), mainly as neochlorogenic and chlorogenic acids, and sugar alcohol content may have contributed in the laxative effect of dried plum.^[12]

Although the laxative effect of dried plum and the other health benefits of this fruit have been perceived by the public,^[15] there is still relatively little evidence to provide a cause and effect relationship between the consumption of dried plum and maintenance of normal bowel function.^[8] Therefore, this study was conducted to compare the effect of different doses of daily dried plum consumption on the bowel habits of older postmenopausal women.

Materials and methods

Subjects

Postmenopausal women (n=84) 65–79 years of age who were not on hormone replacement therapy for at least 3 months before the initiation of the study were recruited from a parent study evaluating the effect of dried plum consumption on bone mineral density (BMD) and bone biomarkers. Of the women recruited, 48 met the eligibility criteria for this study. Recruitment took place from the greater San Diego, California area via flyers at local gyms, senior centres, markets, and word of mouth between August 2012 and September 2013. Women whose BMD t-score at any site fell below –2.5 standard deviation (SD) of the mean were excluded from the study. Other exclusion criteria were history of GI disorders, cancer, diabetes, thyroid disorders, liver or kidney diseases, heavy smoking (more than 20 cigarette per day), respiratory diseases, pelvic inflammation, or endothelial polyps. All women who participated were non-smokers. Women who regularly consumed dried plum or prune juice were not included in the study. All procedures involving human subjects were approved by the Institutional Review Board at San Diego State University (approval number 919088). All subjects signed an informed consent form. The participants were advised to maintain their usual physical activity and diet patterns throughout the duration of the study.

Study design

A total of 48 eligible postmenopausal women were randomly assigned into three different groups; control, 50 g/day, and 100 g/day dried plum groups. Dried plums were provided in portioned packages. All participants received 500 mg calcium from calcium carbonate plus 400 IU vitamin D3 (cholecalciferol) daily. Sixteen individuals were allocated to each group and dried plum groups were asked to incorporate dried plum into their diet for 6 months. The amount of dried plum was based on the findings of our long-term clinical trials.^[16–18] The calculated values for the energy and nutrient (fat, carbohydrate, fibre, protein, calcium, and phosphorus) composition of the dried plum regimens are displayed in Table 1.

Table 1. Nutrient concentration of 50 g and 100 g dried plum obtained by both calculation and actual analyses.

	Dried Plum (Per 50 g)		Dried Plum (Per 100 g)
	Calculated^a	Actual^b	Calculated^a	Actual^b
Energy (Kcal)	119.5	110	239	220
Fat (g)	0.26	0.12	0.52	0.23
Total Carbohydrates (g)	31.4	31.7	62.7	63.4
Fiber (g)	3.55	Not assessed	7.10	Not assessed
Protein (g)	1.31	1.12	2.61	2.24
Calcium (mg)	25.5	15.0	51.0	30.0
Phosphorus (mg)	39.5	25.0	79	50.0

^a Results obtained from Food Processor version 7.50 (ESHA Research, Salem, OR).

^b Gross energy analysed by bomb calorimetry (Parr 1261 Calorimeter, Parr Inst. Co., Moline, IL), crude protein by the AOAC Kjeldahl method, fat by either extraction, and calcium and phosphorus contents by atomic absorption spectrophotometer (Perkin-Elmer Atomic Absorption Spectrophotometer, model 5100PC, Perkin-Elmer, Norwalk, CT).

Dietary assessment and anthropometric measurements

Participants completed a medical history questionnaire at the beginning of the study. Similarly, physical activity was assessed at baseline and analysed as energy expenditure/week (CHAMPS Physical Activity Questionnaire for Older Adults, Palo Alto, CA, USA). Participants were asked to maintain their current levels of physical activity and to report any major changes. A three-day food record via interview with subject was completed at baseline, 3, and 6 months. Food analysis software (Food Processor version 7.50; ESHA Research, Salem, OR, USA) was used for nutrient analysis. Anthropometric data were collected at baseline and 6 months and height and weight were used to calculate body mass index (BMI) (kg/m²).

Bowel habit assessment

A seven-day bowel movement questionnaire ^[19] was completed by each study participant at baseline, 3 months, and 6 months after beginning of intervention. The bowel habit diary used a 7-point scale and included stool consistency (very hard to very soft), straining during bowel movement (none to extreme), pain during bowel movement (none to extreme), and feeling of constipation after bowel movement (not constipated to very constipated). The amount of stool was estimated based on comparing the amount produced relative to a cup, i.e., 1/4, 1/2, and 1 cup.

Statistical analysis

Data were analysed using repeated-measures analysis of variance methods with PROC MIXED in PC SAS (Version 9.1, SAS Institute, Cary, NC) for the main and interaction effects of treatment (0 g/day, 50 g/day, or 100 g/day dried plum) and time (baseline, 3 months, and 6 months). The mean changes in each time point for the treatment groups were compared by analysing the interaction effects of the two factors, treatment and time, using the SLICE option in an LSMEANS statement. Data are reported as mean ± SD. p < 0.05 was regarded as statistically significant.

Result

Forty-two women (13 on control, 16 on 50 g/day dried plum, and 13 on 100 g/day dried plum) completed the study. The attrition rate was 18.75% for control, 0% for 50 g/day, and 18.75% for 100 g/day. Subject characteristics of the women who completed the study are presented in Table 2. There were no significant differences in age, last menstrual period age, height, weight, or BMI at baseline and between three groups. Adherence to control and dried plum regimens, as indicated by the self-monitoring checklist provided to them on a monthly basis and by assessing a three-day food record, was high. The compliance to the dried plum regimens was on average 95% for 50 g dried plum and 97% for 100 g dried plum group, and the compliance for calcium supplement was on average 95.4% for 50 g dried plum and 99.4 % for 100 g dried plum group. Analysis of the three-day food record revealed no significant difference for participants’ food intake from their corresponding baseline value between the three treatment groups throughout the study period (Table 3). There were no significant differences in physical activity levels between the treatment groups at baseline (Table 2).

Table 2. Characteristics of study participants.

	0 g Dried Plum		50 g Dried Plum		100 g Dried Plum
Measures	Baseline	6 Months	Baseline	6 Months	Baseline	6 Months
Age (years)	71.0±2.9	-	68.5±4.3	-	70.4±3.7	-
LMP age (years)	49.1±6.6	-	49.3±7.6	-	49.3±7.7	-
Weight (kg)	65.0±10.6	65.7±9.6	64.5±12.1	62.8±11.6	65.5±8.9	65.9±9.6
Height (cm)	161.2±7.0	-	161.7±6.0	-	162.0±7.2	-
BMI	25.0±4.3	25.3±4.7	24.8±3.9	24.2±3.8	24.9±4.0	25.1±3.6
PA (kcal/day)	763±366.6	-	658±455.2	-	715±349.5	-

Values are mean ± SD, n= 48. The CHAMP Physical Activity Questionnaire for older adults was used to assess current physical activity pattern including leisure, occupational, and home activities. There were no statistical significant differences observed between baseline values of three treatment groups and between baseline and 6- month corresponding values.

^aLMP; Last menstrual period

^bBMI; body mass index

^cPA; physical activity

Table 3. Daily nutrient intake calculated from 3-day food record at baseline, 3 months, and 6 months supplemented with 0 g, 50 g, and 100 g dried plum.

Dried Plum	Control (0 g/day) [n=13]			50 g/day [n=16]			100 g/day [n=13]
Daily Intake	Baseline	3 months	6 months	Baseline	3 months	6 months	Baseline	3-month	6-month
Macronutrients
Total Energy (Kcal)	2172±873	1907±687	2136±777	1974±641	1922±588	2012±595	1766±701	2003±662	1799±636
Protein (g)	83.6±33	73.0±27	82.9±24	67.7±24	67.8±24	72.5±25	70.0±30	72.7±25	61.6±25
Carbohydrate (g)	275±109	260±118	302±155	238±84	243±79	237±50	232±96	245±78	229±110
Dietary fibre (g)	26.1±15	26.9±12	22.9±14	27.1±11	28.9±9	29.0±9	24.0±14	24.0±12	27.3±12
Fat (g)	76.2±45	77.8±22	78.0±28	73.8±35	79.6±32	80.1±47	72.1±34	79.5±47	72.3±27
Vitamins
Vitamin A (mg)	2.43±0.23	2.32±0.14	2.64±0.14	2.58±0.13	2.65±0.13	3.00±0.04	2.30±0.20	2.31±0.26	2.28±0.50
Vitamin C (mg)	156±5	111±8	125±10	157±15	142±17	117±5	113±9	124±6	142±7
Vitamin E (mg)	5.9±0.3	5.4±0.5	6.7±0.5	4.6±0.3	7.3±1.2	6.8±0.7	5.4±0.6	6.0±0.4	6.0±0.5
Vitamin K (µg)	157.9±7.6	153.8±6.3	150.7±10.1	151.1±7.6	164.8±15.0	199.1±35.8	136.9±12.6	144.4±9.1	226.3±13.9
Vitamin D (µg)	1.9±0.9	2.5±0.4	2.4±0.3	1.9±0.5	2.0±0.2	1.6±0.1	2.0±0.1	1.6±0.1	1.31±0.5
Minerals (mg)
Calcium	750.8±87	790.5±47	765.2±37	710.9±58	744.3±29	773.0±29	784.4±27	774.6±26	769.8±33
Magnesium	187.4±13	180.8±19	168.9±19	196.4±15	214.4±14	174.6±18	183.9±19	194.0±14	199.2±11
Iron	15.5±0.3	16.8±1.2	13.0±0.7	13.4±0.8	15.7±0.9	14.9±0.6	10.3±0.9	12.0±0.9	10.7±0.7
Phosphorus	767.0±48	520±26	665±30	706±49	622±33	604±24	615±32	549±17	561±36

Values are mean ± SD. Analyses do not include dried plum consumption and calcium and vitamin D from the supplements used by participants. There were no statistical significant differences observed between the baseline values of three treatment groups and between baselines, 3 months, and 6 months corresponding values.

We did not observe any significant changes for average estimated faecal bulk between groups at 3 and 6 months. At 6 months, the overall feeling of constipation increased in the control group significantly in comparison to the 100 g dried plum group. Feeling of pain significantly increased in the control group at 6 months compared to the 50 g dried plum group. In addition, at 3 months, the feeling of pain significantly decreased in the 100 g dried plum groups compared to the 50 g dried plum group (Figs. 1A–1F).

Figures 1. A to 1F. For each graph, values are mean ± SD. Figures 1A through 1F reflect the effects of dried plum (0 g, 50 g, and 100 g) for 6 months on bowel movement habits. Figures 1A and 1B represent number of bowel movements and amount of stool produced per day, respectively. Figures 1C through 1F are based on a scale of 1–7.

* = Different between groups at the same time point (p< 0.05).

Discussion

This study supports the traditional use of dried plum as a treatment for constipation as well as the limited scientific evidence available, suggesting improvements in bowel habits. Although dried plum has been demonstrated to produce many health benefits,^{[16–18,20–24]} many people are reluctant to incorporate dried plum into their daily diet due to the perception that dried plum promotes unfavourable bowel movement responses. Although lifestyle modification including increased dietary fibre intake has been recommended as first-line therapy for constipation, there is not enough evidence to support this approach.^[4,8] Moreover, only a few trials have looked at the effect of naturally occurring food-based dietary fibre on managing constipation ^[4] and the protective effect of dietary fibre against some GI disorders including colorectal cancer, which is a significant cause of morbidity and mortality throughout the world.^[25] It has been suggested that the positive effects of dietary fibre on GI function are via its effect on stool weight and GI transit time.^[7] The findings of this study indicate that the daily intake of both 50 g and 100 g of dried plum by older postmenopausal women without any bowel problem did not cause unfavourable changes in bowel habits, and modestly favourable ratings were detected for pain and general feelings of constipation when dried plums were consumed compared to the control group. Similarly, a study by Lucas et al. ^[26] did not report any undesirable changes in bowel function by postmenopausal women with no history of bowel problems consuming daily 100 g of dried plum for 3 months. Additionally, Tinker et al. ^[23] did not observe any GI disturbances, including diarrheal or loose stool among men consuming daily 100 g of dried plum for four weeks. Moreover, Howarth et al. ^[14] reported that dried plum consumption did not cause adverse effect on bowel function and promoted softer stools in women 25–54 years of age.

Improved bowel functions by dried plum have been attributed to many different factors including insoluble and soluble fibres as well as sorbitol (~7.1 g per 100 kcal of dried plums), which promote softer stools and improved motility.^[14] Previous studies ^[27–30] reported that wheat fibre increases faecal bulk by 3–6 g for each additional gram consumed. Having approximately 7 g of total fibre, including soluble and insoluble fibre, per 100 g, dried plum is potential to modestly improve intestinal motility ^[22].

Although it has been reported that calcium may cause constipation ^[31,32], in this study, concurrent consumption of dried plum yielded modestly favourable ratings of pain and general feelings of constipation in comparison to supplementation of calcium/vitamin D among elderly postmenopausal women. Since supplementation with calcium and vitamin D is common, practitioners should consider recommending dried plum consumption for patients using a similar supplementation regimen.

Conclusion

Not only is dried plum a rich source of fibre and sorbital, it is also a fruit that provides a variety of health benefits in reducing risk of atherosclerosis, cardiovascular disease, and osteoporosis. Unfortunately, many individuals may not take advantage of the potential health benefits of dried plum due to the assumption that this fruit causes unfavourable bowel habit changes; however, the findings of this study are in agreement with previous research ^[14,23,26] indicating that postmenopausal women can incorporate up to 100 g of dried plum into their daily diet without negative changes in bowel habits. Moreover, based on the findings of this study, dried plum not only does not have any adverse effect on GI function, but this fruit also significantly decreased the feeling of pain and constipation among elderly postmenopausal women using calcium and vitamin D supplements.

Acknowledgements

We gratefully acknowledge the valuable assistance of the following students at San Diego State University: Mariana Beleche, Sofie Blicher, Jayme Brisco, Bich Thuy Callens, Zachary Clayton, Amanda Cravinho, Jennifer Cullison, Sofia Garcia, Jackie Gaylis, Montserrat Gonzalez, Mairi McLachlan, Dina Metti, Tasnim El Mezain, Rose Miller, Ivette Navarro, Dawn Ortiz, and Yenina Vereda. This project was supported by the SDSU Research Foundation grant number #57114A. The authors thank the California Dried Plum Board for providing us with dried plums and we gratefully acknowledge Nutrisystem, Inc. for supplying calcium and vitamin D supplements for the study.