Dietary fiber intake and endogenous serum hormone levels in naturally postmenopausal Mexican American women: the Multiethnic Cohort Study

This study investigated dietary fiber intake in association with serum estrogen levels in naturally postmenopausal Latina women with a wide range of fiber intake. Estrone (E1), estradiol (E2), and sex-hormone-binding globulin (SHBG) were measured in 242 women. Associations between estrogen levels and intake of dietary fiber, including insoluble and soluble fractions, quantified from a food frequency questionnaire, were examined. The biomarker enterolactone was also measured. After adjustment for age, weight, and other nondietary factors, dietary fiber intake was inversely associated with E1 and E2; there was a 22% and 17% decrease (2Ptrend=0.023 and 0.045) among subjects in the highest quintile of intake compared with the lowest. Fitting dietary fiber together with soluble and insoluble nonstarch polysaccharides (NSP) showed a much greater decrease in E1 and E2 (47% and 41%, respectively) while increased soluble NSP intake showed increases in E1 and E2 (64% and 69%, respectively). Two foods, avocado and grapefruit, showed significant positive associations with E1 (2Ptrend=0.029 and 0.015, respectively). This study suggests that different components of dietary fiber may have very significant different effects on serum estrogen levels. The suggestive findings relating increased estrogen levels to avocado and grapefruit intakes need confirmation.     

The Effect of Grapefruit Intake on Endogenous Serum Estrogen Levels in Postmenopausal Women

Although grapefruit intake leads to elevated serum estrogen levels when hormones are taken orally, there are no published data on the effect on endogenous levels. We conducted a pilot dietary intervention study among healthy postmenopausal volunteers to test whole grapefruit, 2 juices, and 1 grapefruit soda. Fifty-nine participants were recruited through the Love/Avon Army of Women. The study consisted of a 3-wk run-in, 2 wk of grapefruit intake, and a 1-wk wash-out. Eight fasting blood samples were collected. An additional 5 samples drawn at 1, 2, 4, 8, and 10 hr after grapefruit intake were collected during an acute-phase study for 10 women. Serum assays for estrone (E₁), estradiol (E₂), estrone-3-sulfate (E₁S), dehydroepiandrosterone sulfate, and sex hormone-binding globulin were conducted. Whole grapefruit intake had significant effects on endogenous E₁S. Peak effects were seen at 8 hr, increasing by 26% from baseline. No changes in mean E₁ or E₂ with whole fruit intake were observed. In contrast, fresh juice, bottled juice, and soda intake all had significant lowering effects on E₂. The findings suggest an important interaction between grapefruit intake and endogenous estrogen levels. Because endogenous estrogen levels are associated with breast cancer risk, further research is warranted.     

Dietary fiber intake and risk of breast cancer by menopausal and estrogen receptor status

Purpose

Evaluate the hypothesis that relation of breast cancer associated with dietary fiber intakes varies by type of fiber, menopausal, and the tumor’s hormone receptor status.

Methods

A case–control study of female breast cancer was conducted in Connecticut. A total of 557 incident breast cancer cases and 536 age frequency-matched controls were included in the analysis. Information on dietary intakes was collected through in-person interviews with a semi-quantitative food frequency questionnaire and was converted into nutrient intakes. Odds ratios and 95% confidence intervals were estimated by unconditional logistic regression.

Results

Among pre-menopausal women, higher intake of soluble fiber (highest versus lowest quartile of intake) was associated with a significantly reduced risk of breast cancer (OR = 0.38, 95% CI, 0.15–0.97, P _trend = 0.08). When further restricted to pre-menopausal women with ER^? tumors, the adjusted OR for the highest quartile of intake was 0.15 (95% CI, 0.03–0.69, P _trend = 0.02) for soluble fiber intake. Among post-menopausal women, no reduced risk of breast cancer was observed for either soluble or insoluble fiber intakes or among ER⁺ or ER^? tumor groups.

Conclusions

The results from this study show that dietary soluble fiber intake is associated with a significantly reduced risk of ER^? breast cancer among pre-menopausal women. Additional studies with larger sample size are needed to confirm these results.     

Dietary Fiber Intakes and Insulin Requirements Pregnant Women with Type 1 Diabetes

Objective To determine whether higher dietary fiber intake (water soluble and insoluble) is associated with lower insulin requirements and better glycemic control in pregnant women with type 1 diabetes consuming a self-selected diet.Design A longitudinal, observational study.Subjects Pregnant women (n=141) with type 1 diabetes participating in an interdisciplinary program examining the effects of glycemic control on pregnancy outcome (Diabetes and Pregnancy Program, University of Cincinnati Medical Center).Measurements We determined total, water soluble and insoluble fiber intakes f, om 3-day food records kept each trimester during pregnancy. Outcome measures were insulin dose, pre-meal blood glucose, and glycated hemoglobin concentrations.Statistical analyses Correlation coefficients, multiple regression, mixed-model analysis of variance.Results Mean intakes (g/day) of total, water soluble fiber, and insoluble fiber were 14.0 (range, 1.8-33.1), 4.8 (range, 0.6-10.5) and 9.0 (range, 1.1-24.0), respectively. In the second and third trimesters of pregnancy, insulin requirements were inversely associated with total, water soluble, and insoluble fiber intakes; the correlation coefficients ranged from −0.22 to −0.17 (P=.02 to 0.08). Insulin requirements associated with a higher fiber intake (20.5 g/day) were 16% to 18% lower than for a lower fiber intake (8.1 g/ day). These relations remained after adjustment for body weight, disease severity and duration, insulin type, and study year in the second (P=.03 to 0.10) but not in the third trimester. Pre-meal blood glucose and glycated hemoglobin concentrations were not associated with fiber intake.Conclusions Among pregnant women with type 1 diabetes, higher fiber intake is associated with lower daily insulin requirements. Dietary fiber intake should be considered when counseling patients about the management of blood glucose concentrations. J Am Diet Assoc. 2001; 101: 305-310.     

Defatted avocado pulp reduces body weight and total hepatic fat but increases plasma cholesterol in male rats fed diets with cholesterol

The potential use of avocado as a fiber source was evaluated. The total dietary fiber content of fresh avocado fruit of the Ettinger variety was 5.2 g/100 g. Approximately 75% was insoluble, and 25% soluble. The water-holding capacity of dry defatted avocado pulp was similar to that of cellulose, and trypsin inhibitors were not detected. The dietary and metabolic consequences of the avocado pulp were studied in male rats fed normal and hypercholesterolemic diets. Rats consumed semipurified diets containing either avocado pulp as the dietary fiber source or cellulose (control) with or without 10 g/kg cholesterol and 5 g/kg cholic acid. Food consumption and body weight gain were lower in rats fed avocado compared with those fed cellulose. Relative cecum weight was higher in avocado-fed rats. Plasma and hepatic cholesterol levels did not differ in rats fed diets without cholesterol, but plasma cholesterol was greater in avocado-fed than in cellulose-fed rats that consumed cholesterol. Regardless of dietary cholesterol, hepatic total fat levels, as evaluated histologically, but not directly, were lower in avocado-fed rats. These data suggest the presence of an appetite depressant in avocado and that avocado pulp interferes with hepatic fat metabolism.     

Soy milk and dairy consumption is independently associated with ultrasound attenuation of the heel bone among postmenopausal women: the Adventist Health Study-2

Soy milk has become a popular substitute for dairy milk with important health claims. We hypothesized that soy milk, based on its nutrient composition, is comparable to dairy products and, therefore, beneficial for bone health. To test this hypothesis, we examined the benefit of soy milk and dairy products intake on bone health using broadband ultrasound attenuation of the calcaneus. Postmenopausal white women (n = 337) who had completed a lifestyle and dietary questionnaire at enrollment into the Adventist Health Study-2 had their calcaneal broadband ultrasound attenuation measured 2 years later. The association between osteoporosis (defined as a T-score <−1.8) and some dietary factors (soy milk, dairy) and selected lifestyle factors was assessed using logistic regression. In a multivariable model adjusted for demographics, hormone use, and other dietary factors, osteoporosis was positively associated with age (odds ratio [OR] = 1.08; 95% confidence interval [CI], 1.06-1.12) and inversely associated with body mass index (OR = 0.91; 95% CI, 0.86-0.97) and current estrogen use (OR = 0.27; 95% CI, 0.13-0.56). Compared with women who did not drink soy milk, women drinking soy milk once a day or more had 56% lower odds of osteoporosis (OR = 0.44; 95% CI, 0.20-0.98; P_trend = .04). Women whose dairy intake was once a day or more had a 62% reduction in the likelihood of having osteoporosis (OR = 0.38; 95% CI, 0.17-0.86; P_trend = .02) compared with women whose dairy intake was less than twice a week. Among individual dairy products, only cheese showed an independent and significant protection (OR = 0.28; 95% CI, 0.12-0.66; P_trend = .004) for women eating cheese more than once per week vs those who ate cheese less than once a week. We concluded that osteoporosis is inversely associated with soy milk intake to a similar degree as dairy intake after accounting for age, body mass index, and estrogen use.     

Barley and wheat foods: influence on plasma cholesterol concentrations in hypercholesterolemic men.

Twenty-one mildly hypercholesterolemic men aged 30-59 y were provided with comparable barley and wheat foods for each of 4 wk in a crossover-designed experiment. The purpose of the study was to examine the influence of two sources of dietary fiber (nonstarch polysaccharides, NSP) on blood lipids and glucose concentrations. Barley contains beta-glucan as a source of soluble dietary fiber (DF) whereas wheat contains the largely insoluble cellulose and hemicellulose fiber. Total dietary fiber increased from a previous intake of 21-38 g/d during the period of study for the two groups. Consumption of barley relative to wheat foods was associated with a significant fall in both plasma total cholesterol (6%, P less than 0.05) and in low-density-lipoprotein cholesterol (7%, P less than 0.02) whereas triglyceride and glucose concentrations did not change significantly. It is concluded that barley dietary fiber is more effective than wheat dietary fiber at lowering blood cholesterol in hypercholesterolemic men.     

Total n-3 polyunsaturated fatty acid intake is inversely associated with serum C-reactive protein in young Japanese women

Little is known about the relation of dietary factors to circulating C-reactive protein (CRP) concentrations in young adults and non-Western populations. We cross-sectionally examined associations between dietary intake and serum CRP concentrations in young Japanese women. The subjects were 443 female Japanese dietetic students aged 18 to 22 years. Dietary intake was assessed with a validated, self-administered, comprehensive, diet history questionnaire. Serum CRP concentrations were measured by highly sensitive nephelometry. The prevalence of elevated CRP (≥1 mg/L) was 5.6%. After adjustment for possible confounding factors including body mass index, a significant inverse association was seen between total n-3 polyunsaturated fatty acid intake and elevated CRP. The multivariate adjusted odds ratios of elevated CRP for women with intake below and above the median (1.1% of energy) were 1.00 and 0.33 (95% confidence interval, 0.13-0.82; P = .02), respectively. Intake of eicosapentaenoic acid + docosahexaenoic acid and α-linolenic acid was not associated with elevated CRP concentrations (P = .62 and P = .27, respectively). Vitamin C intake was independently inversely associated with elevated CRP, although the association was nonsignificant (P = .10). No clear associations were observed for other dietary factors examined including total fat, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, total dietary fiber, soluble dietary fiber, insoluble dietary fiber, and magnesium; fruits, vegetables, and fish and shellfish; and dietary glycemic load (P = .27 to P = .99). In conclusion, total n-3 polyunsaturated fatty acid intake showed an independent inverse association with elevated serum CRP concentration in a group of young Japanese women.     

Development and Validation of a Mobile Phone Application Developed for Measuring Dietary Fiber Intake

We have developed a mobile phone application for measuring the intake of dietary fiber and validated the ability of the application to accurately capture this intake against measurements registered by a dietary record. We also investigated what food groups contributed most to the total, soluble, and insoluble dietary fiber intake. Twenty-six randomly selected Swedish women aged 35–85 years were included and randomized to either start to register dietary intake in the application or by a dietary record, during three consecutive days. After a washout period of at least two weeks, the participants used the other method. We found that the difference in measured mean fiber intake between the dietary record and the application was two grams independent of the total intake per day. A statistically significant correlation between fiber intake as measured by the two methods was found (rho = 0.65, p < 0.001). Vegetables and roots were the predominantly contributing foods to total and soluble fiber intake. Bread and crackers contributed most to insoluble fiber intake. In conclusion, the application may be considered as a useful and easy-to-use method to measure dietary fiber intake.     

Dietary fiber intake and risk of type 2 diabetes: a dose–response analysis of prospective studies

Observational studies suggest an association between dietary fiber intake and risk of type 2 diabetes, but the results are inconclusive. We conducted a meta-analysis of prospective studies evaluating the associations of dietary fiber intake and risk of type 2 diabetes. Relevant studies were identified by searching EMBASE (from 1974 to April 2013) and PubMed (from 1966 to April 2013). The fixed or random-effect model was selected based on the homogeneity test among studies. In addition, a 2-stage random-effects dose–response meta-analysis was performed. We identified 17 prospective cohort studies of dietary fiber intake and risk of type 2 diabetes involving 19,033 cases and 488,293 participants. The combined RR (95 % CI) of type 2 diabetes for intake of total dietary fiber, cereal fiber, fruit fiber and insoluble fiber was 0.81 (0.73–0.90), 0.77 (0.69–0.85), 0.94 (0.88–0.99) and 0.75 (0.63–0.89), respectively. A nonlinear relationship was found of total dietary fiber intake with risk of type 2 diabetes (P _{for nonlinearity} < 0.01), and the RRs (95 % CI) of type 2 diabetes were 0.98 (0.90–1.06), 0.97 (0.87–1.07), 0.89 (0.80–0.99), 0.76 (0.65–0.88), and 0.66 (0.53–0.82) for 15, 20, 25, 30, and 35 g/day. The departure from nonlinear relationship was not significant (P _{for nonlinearity} = 0.72), and the risk of type 2 diabetes decreased by 6 % (RR 0.94, 95 % CI 0.93–0.96) for 2 g/day increment in cereal fiber intake. Findings from this meta-analysis indicate that the intakes of dietary fiber may be inversely associated with risk of type 2 diabetes.     

Postprandial glucose,insulin, and lipid responses to four meals containing unpurified dietary fiber in non-insulin-dependent diabetes mellitus (NIDDM), hypertriglyceridemic subjects.

To evaluate the effects of two levels of total dietary fiber (10 g vs. 20 g) and two soluble:insoluble fiber ratios (1:4 vs. 2:3) on postprandial glucose and lipid metabolism in hypertriglyceridemic subjects with non-insulin-dependent diabetes mellitus (NIDDM).

Eight NIDDM, mildly hypertriglyceridemic subjects consumed four test breakfasts, each containing variable proportions of the same cereal and fruit fiber sources. Blood samples were obtained during the 4 hours following the test meals and analyzed for glucose, insulin, triglyceride, total cholesterol and high density lipoprotein cholesterol.

The incremental area under the curve for glucose and insulin was lowered after consuming 20 g as compared to 10 g of dietary fiber (p < 0.05), but was not affected by the soluble insoluble fiber ratio. The postprandial lipemia was similar after all test meals.

The proportion of soluble to insoluble fiber in cereal and fruit does not necessarily predict the effect of fiber on the glycemic response, while the overall quantity of fiber does appear to affect postprandial glucose metabolism in NIDDM.     

53例糖尿病患者膳食中膳食纤维的摄入量调查

目的调查糖尿患者总膳食纤维、可溶及不可溶性膳食纤维的摄入量,为糖尿患者膳食纤维营养状况的研究提供重要基础数据。方法通过不同实验室间的比对研究建立膳食纤维酶重量分析方法。采用称重法和食物计量图片法登记53例糖尿患者连续3d每餐的食物摄入种类和重量,利用酶重量法建立的食物中膳食纤维数据库计算膳食纤维摄入的数量和种类。结果3个实验室测定膳食纤维数据的相对标准偏差在2.63%~9.67%之间。调查对象蔬菜类食物摄入量最多,是膳食纤维的主要来源。调查对象总膳食纤维摄入量为(26.5±9.8)g/d,不可溶性膳食纤维摄入量为(14.6±5.8)g/d,可溶性膳食纤维摄入量为(10.4±4.4)g/d。结论本次调查对象的总膳食纤维日摄入量处于美国糖尿病协会推荐摄入量范围内。     

Association between dietary fiber and markers of systemic inflammation in the Women's Health Initiative Observational Study

OBJECTIVE: Systemic inflammation may play an important role in the development of atherosclerosis, type 2 diabetes, and some cancers. Few studies have comprehensively assessed the direct relations between dietary fiber and inflammatory cytokines, especially in minority populations. Using baseline data from 1958 postmenopausal women enrolled in the Women's Health Initiative Observational Study, we examined cross-sectional associations between dietary fiber intake and markers of systemic inflammation (including serum high-sensitivity C-reactive protein [hs-CRP], interleukin-6 [IL-6], and tumor necrosis factor-alpha receptor-2 [TNF-alpha-R2]) in addition to differences in these associations by ethnicity. METHODS: Multiple linear regression models were used to assess the relation between fiber intake and makers of systemic inflammation. RESULTS: After adjustment for covariates, intakes of dietary fiber were inversely associated with IL-6 (P values for trend were 0.01 for total fiber, 0.004 for soluble fiber, and 0.001 for insoluble fiber) and TNF-alpha-R2 (P values for trend were 0.002 for total, 0.02 for soluble, and <0.001 for insoluble fibers). Although the samples were small in minority Americans, results were generally consistent with those found among European Americans. We did not observe any significant association between intake of dietary fiber and hs-CRP. CONCLUSION: These findings lend support to the hypothesis that a high-fiber diet is associated with lower plasma levels of IL-6 and TNF-alpha-R2. Contrary to previous reports, however, there was no association between fiber and hs-CRP among postmenopausal women. Future studies on the influence of diet on inflammation should include IL-6 and TNF-alpha-R2 and enroll participants from ethnic minorities.     

Dietary Iron Intake and Risk of Endometrial Cancer: A Population-Based Case-Control Study in Shanghai,China

Dietary red meat and animal fat have been linked to endometrial cancer (EC) risk, but the impact of bioavailable iron in animal-derived foods has been less well studied. Our objective was to investigate the effects of iron and fats on the risk of EC in a large, population-based, case-control study. The Shanghai Endometrial Cancer Study enrolled 1,204 EC cases and 1,212 controls who completed in-person interviews, including a food frequency questionnaire. Animal-derived iron and fat intakes were calculated from dietary intakes and food composition tables. Logistic regression models were used to evaluate independent and joint effects of iron and fat on EC risk. Animal-derived iron intake was positively associated with EC risk [adjusted OR = 1.9; 95% CI = 1.4–2.7, P _trend < 0.01, highest vs. lowest quartile], predominantly after menopause (OR = 2.2; 95%CI = 1.4–3.4, P _trend < 0.01) and in women with BMI ≥ 25 kg/m ² (OR = 3.2; 95% CI = 1.4–7.5 in postmenopausal obese women, P _trend < 0.01). Animal-derived fat was also associated with postmenopausal EC risk (OR = 1.7; 95% CI = 1.2–2.5, P _trend < 0.01). Multiplicative interactions between animal-derived iron and BMI or animal-derived fat intake were not observed. Animal-derived iron intake is associated with increased risk of EC after menopause and among obese women. Avoidance of animal-derived (heme) iron may reduce the risk of EC in these women.     

Individual Sugars, Soluble, and Insoluble Dietary Fiber Contents of 70 High Consumption Foods

As part of the continuous efforts of the Nutrient Data Laboratory, Agricultural Research Service (ARS), USDA in updating and expanding the carbohydrate data in its database, foods were selected based on dietary fiber content and frequency of consumption. They were analyzed by a commercial testing laboratory under a USDA contract. Individual sugars, soluble and insoluble dietary fiber values of 70 foods in six food groups were reported. Foods included 14 baked products, 10 cereal grains and pastas, 19 fruits, seven legumes, 10 cooked vegetables, and 10 raw vegetables. Except for cereal grains/pasta and legumes, most other foods contained fructose and glucose; sucrose was found in almost all except baked products, which were the most predominant source of maltose. Fruits contained the most total sugar and cereal, grains/pasta the least. Legumes contained the highest amount of total dietary fiber. All these commonly consumed foods, with the exception of cooked white rice, contained both soluble and insoluble dietary fiber. The percent of soluble and insoluble fiber varied across food groups, even within each group. Comparison of data from the commercial laboratory with those of the same food analyzed in the Food Composition Laboratory using different methods indicated there was good agreement between high-performance liquid chromatographic and gas chromatographic methods for the determination of individual sugars. Total dietary fiber as calculated from the sum of soluble and insoluble fiber according to AOAC Method 991.43 and total dietary fiber from direct analysis using a single enzyme-gravimetric method showed high variability (r²<0.8) for three of the six food groups, but good agreement for others.     

Intake of Vitamins D and A and Calcium and Risk of Non-Hodgkin Lymphoma: San Francisco Bay Area Population-Based Case-Control Study

Several nutrients identified as potentially cancer protective have been inconsistently associated with non-Hodgkin lymphoma (NHL) risk. Dietary history data, including use of vitamin supplements, were collected using a semiquantitative food frequency questionnaire administered during in-person interviews with 4,133 participants (2,052 cases, 2,081 controls) in a San Francisco Bay Area population-based case-control study. Data were used to determine the association of intake levels of vitamins D and A and calcium with risk of NHL and NHL subtypes. Odds ratios (OR) and 95% confidence intervals (CI) were computed as estimates of relative risk using adjusted unconditional logistic regression. Increasing vitamin D intake from food and supplements was positively associated with NHL risk in men (5th quintile: OR = 1.6, 95% CI = 1.0–2.4, P _trend = 0.07) and with diffuse large B-cell lymphoma (DLBCL) in women and men (5th quintile: OR = 1.6, 95% CI = 1.0–2.5, P _trend = 0.02); that was largely due to the effect in men (P _trend = 0.03). These results do not support a strong role for vitamin D intake with NHL risk, with the exception of a potential association for DLBCL risk in men. Our results should be interpreted conservatively until further investigation in larger pooled studies can be conducted to better assess the role of vitamin D intake in lymphomagenesis.     

Associations of Calcium,Vitamin D,and Dairy Product Intakes with Colorectal Cancer Risk among Older Women: The Iowa Women’s Health Study

Calcium and, to a lesser extent, dairy products are consistently modestly inversely associated with colorectal cancer (CRC). Dairy products may contain components other than calcium and fat, such as insulin-like growth factor-1, that may affect CRC risk. In the prospective Iowa Women’s Health Study, calcium, dairy product, and vitamin D intakes were assessed using a semiquantitative food frequency questionnaire. To investigate dairy products independent of their calcium components, we estimated residuals from linear regression models of their associations with dietary calcium. Of the 35,221 55–69-year-old cancer-free women at baseline in 1986, 1,731 developed CRC during follow-up through 2012. For those in the highest relative to the lowest intake quintiles, the adjusted hazards ratios and 95% confidence intervals from multivariable Cox proportional hazards regression models for overall and distal CRC were 0.81 (0.67–0.98; P_trend = 0.004) and 0.59 (0.44–0.80; P_trend = 0.003), respectively, for total calcium; and 0.79 (0.66–0.94; P_trend = 0.01) and 0.69 (0.53–0.90; P_trend = 0.003) for total dairy products, respectively. The various dairy product residuals were not associated with CRC. These results support that, among women, calcium and dairy products may be inversely associated with CRC—perhaps primarily distal CRC—but suggest that the non-calcium, non-fat component of dairy products may not be associated with CRC.     

Association between Intake of Energy and Macronutrients and Memory Impairment Severity in US Older Adults,National Health and Nutrition Examination Survey 2011–2014

Without a cure, dementia affects about 50 million people worldwide. Understanding the effects of dietary habits, a key lifestyle behavior, on memory impairment is critical to inform early behavioral modification to delay further memory loss and progression to dementia. We examined the associations of total energy intake and energy intake from macronutrients with memory impairment among older US adults using data from the nationally representative National Health and Nutrition Examination Survey study 2011–2014. A total of 3623 participants aged ≥60 years were analyzed. Comparing to those with low total energy intake, individuals with high intake were more likely to have severe memory impairment (OR: 1.52, 95% CI: 1.15 to 2.02; p_trend = 0.005). Specifically, higher energy intake from carbohydrate (OR: 1.59, 95% CI: 1.12 to 2.26) and sugar (OR: 1.54, 95% CI: 1.11 to 2.16) were both significantly associated with the presence of memory impairment. Additionally, higher energy intake from fat, carbohydrate and sugar were significantly associated with more server memory impairment (fat: p_trend = 0.04; carbohydrate: p_trend = 0.03; sugar: p_trend = 0.02). High energy intake, either total or from carbohydrates, fat or sugar, is associated with memory impairment severity in the older US population. No such association was found in energy intake from protein.     

Dietary fiber intakes and insulin requirements in pregnant women with type 1 diabetes

OBJECTIVE: To determine whether higher dietary fiber intake (water soluble and insoluble) is associated with lower insulin requirements and better glycemic control in pregnant women with type 1 diabetes consuming a self-selected diet. DESIGN: A longitudinal, observational study. SUBJECTS: Pregnant women (n=141) with type 1 diabetes participating in an interdisciplinary program examining the effects of glycemic control on pregnancy outcome (Diabetes and Pregnancy Program, University of Cincinnati Medical Center). MEASUREMENTS: We determined total, water soluble and insoluble fiber intakes from 3-day food records kept each trimester during pregnancy. Outcome measures were insulin dose, pre-meal blood glucose, and glycated hemoglobin concentrations. STATISTICAL ANALYSES: Correlation coefficients, multiple regression, mixed-model analysis of variance. RESULTS: Mean intakes (g/day) of total, water soluble fiber, and insoluble fiber were 14.0 (range, 1.8-33.1), 4.8 (range, 0.6-10.5) and 9.0 (range, 1.1-24.0), respectively. In the second and third trimesters of pregnancy, insulin requirements were inversely associated with total, water soluble, and insoluble fiber intakes; the correlation coefficients ranged from -0.22 to -0.17 (P=.02 to .08). Insulin requirements associated with a higher fiber intake (20.5 g/day) were 16% to 18% lower than for a lower fiber intake (8.1 g/day). These relations remained after adjustment for body weight, disease severity and duration, insulin type, and study year in the second (P=.03 to .10) but not in the third trimester. Pre-meal blood glucose and glycated hemoglobin concentrations were not associated with fiber intake. CONCLUSIONS: Among pregnant women with type 1 diabetes, higher fiber intake is associated with lower daily insulin requirements. Dietary fiber intake should be considered when counseling patients about the management of blood glucose concentrations.     

Dietary fiber and weight regulation

The influence of dietary fiber on energy regulation remains controversial. This review summarizes published studies on the effects of dietary fiber on hunger, satiety, energy intake, and body composition in healthy individuals. Under conditions of fixed energy intake, the majority of studies indicate that an increase in either soluble or insoluble fiber intake increases postmeal satiety and decreases subsequent hunger. When energy intake is ad libitum, mean values for published studies indicate that consumption of an additional 14 g/day fiber for >2 days is associated with a 10% decrease in energy intake and body weight loss of 1.9 kg over 3.8 months. Furthermore, obese individuals may exhibit a greater suppression of energy intake and body weight loss (mean energy intake in all studies was reduced to 82% by higher fiber intake in overweight/obese people versus 94% in lean people; body weight loss was 2.4 kg versus 0.8 kg). These amounts are very similar to the mean changes in energy intake and body weight changes observed when dietary fat content is lowered from 38% to 24% of energy intake in controlled studies of nonobese and obese subjects. The observed changes in energy intake and body weight occur both when the fiber is from naturally high-fiber foods and when it is from a fiber supplement. In view of the fact that mean dietary fiber intake in the United States is currently only 15 g/day (i.e., approximately half the American Heart Association recommendation of 25-30 g/day), efforts to increase dietary fiber in individuals consuming <25 g/day may help to decrease the currently high national prevalence of obesity.