Introductory
Research Question: What is the difference between dietary fiber and a fiber supplement equivalent on postprandial glucose levels?
Hypothesis
If dietary fiber is compared with a fiber supplement equivalent, then there will be a difference in postprandial glucose levels
The dietary supplement industry has sky rocketed in the past 15 years making 20.3 billion dollars in 2004, and the industry continues to grow. Approximately 47.3% of the American population who is older than 2 months is using some type of dietary supplement. (Picciano 2004) This study is important because there is a perceived idea that fiber supplementation will have the same postprandial effects as dietary fiber. Some popular fiber supplements include Fiberwafers, Florafiber, Herblax, Psyllium, Metamucil, and Fibercon(2009).
The supplement we will be using for our study is Psyllium. It is a good source of soluble fiber.
This study may be particularly important to diabetics. 23.6 million Americans have diabetes.
Soluble fibers have been found to be more effective in controlling blood glucose levels than predominantly insoluble fibers. Soluble fibers are found in oats, barley, and citrus, while insoluble fibers are found in wheat (Behall, Scholfield et al. 2006).A study was done to see the effect of fiber on glucose and lipid levels. The diet with the higher amount of fiber (30.5g/d) significantly lowered glucose levels in the healthy test subjects (Aller, de Luis et al. 2004).
Statement of the Problem
The effect of supplemental fiber on blood glucose levels in comparison to dietary fiber eaten at meals is unknown.
Null Hypothesis
There is no significant difference in postprandial blood glucose levels between 12 grams of supplemental fiber and 12 grams dietary fiber.
Testing the Null Hypothesis
Variables
There will be two independent variables; dietary fiber meal and a low fiber meal with fiber supplement. The dependent variable is postprandial blood glucose levels. The control is normal postprandial glucose levels.
There are several extraneous variables: postprandial glucose measurements made at different times on each test subject, consumption of anything (with exception of water) before coming in for the test, test subjects not eating the entire meal, time difference that test subjects take to eat their meals, and user error.
Measuring Variables:
Experienced professionals will be testing their postprandial glucose levels with a blood glucose meter. The level of measurement will be continuous.
Delimitations and Limitations
Our delimitations include, only testing blood glucose levels, not triglycerides or cholesterol (which may also be affected). Test subjects will have a BMI between 18.5 and 24.5, have no history of diabetes in their family, have normal fasting blood glucose levels, will be between the ages of 18-75, and will be ingesting a psyllium husk as their supplemental fiber.
The two biggest limitation of this study will be the lack of financial support and test subjects that meet the criteria.
Assumptions and Operational Definitions
There will be an assumption that all test subjects will have the same reaction to fiber. It is expected that all test subjects' self-report was accurate, will read their glucose meters accurately, and follow the directions precisely. It will also me assumed that the fiber content of food is accurately measured in the food and supplement.
Test subjects will be healthy males or females with no history of diabetes in their extended blood relatives. This includes siblings, parents, aunts, uncles, cousins, or grandparents related by blood. They will have a normal weight defined as a BMI of 18.5-24.9, and range between the ages of 18-75.
The test subjects will be experienced professionals, having a degree in the medical field and experience with using blood glucose meters. They will have a normal fasting glucose level. Normal fasting blood glucose levels range from 60 -100 mg/dL. A normal blood glucose level one hour after eating would be less than 200 mg/dL and less than 140 mg/dL two hours after eating. A higher postprandial glucose level may be a sign of diabetes mellitus(Dugdale 1997).
A laboratory assessment of five glucometers showed significant precision with 4 out of 5 devices measuring within 1.5%-6%. Only one, the Glucometer Gx, varied 7.3%-10.5%. Measurements varied with user error. In the One Touch II gave significantly different results if the strip was overloaded, and for all the devices if the strip was underloaded the results varied. Incubation times affected all meters. In the normoglycaemic range the results obtained with Accutrend and Glucocard were not influenced by even extreme haematocrit values. In the high glucose concentration range there was a decrease in blood glucose values with increasing haematocrit for all meters. This error was smaller with Accutrend and Glucocard than with the other meters.
Since the Accutrend and Glucocard glucose meters were shown to be significantly precise, unless the values imputed were incorrect, we had professionals test their values to insure an accurate reading(Devreese and Leroux-Roels 1993).
Bibliography
(2009). "Dietary Supplement Use (DSQ_D) NHANES 2005-2006." http://www.cdc.gov/nchs/data/nhanes/nhanes_05_06/dsq_d.pdf.
Aller, R., D. A. de Luis, et al. (2004). "Effect of soluble fiber intake in lipid and glucose levels in healthy subjects: a randomized clinical trial." Diabetes Res Clin Pract 65(1): 7-11.
OBJECTIVE: The aim of our work was to carry out a randomized clinical trial with two diets, one enriched in fiber (total fiber 30 g and soluble fiber 4 g) to investigate the effect on lipid and glucose levels in healthy subjects. RESEARCH DESIGN AND METHODS: Fifty-three subjects were prospectively randomized to two groups (see Table 1). Group I received a diet with 10.4 g of fiber given as 1.97 g soluble fiber (pectins, gums and mucilages) and 8.13 g of insoluble fiber (hemicelullose, cellulose and lignins) and Group II received a diet with 30.5 g of fiber of which 4.11 g were soluble fiber and 25.08 g insoluble fiber. Prospective serial assessment of weight and nutritional intake (3 days written food records) were made. These determinations were performed at baseline and at 3 months. All enrolled subjects underwent the following examinations; fasting blood samples were drawn for measurement of total cholesterol, triglyceride concentrations and other lipid fractions, low density lipoprotein (LDL-cholesterol), high density lipoprotein (HDL-cholesterol), glucose, and insulin. RESULTS: Total calorie and fat consumption were lower than recommended in both groups (calories; group I 1633+/-417 kcal per day versus group II 1707.5 +/- 579 kcal per day:ns) and (fats; group I 73.4 +/- 22.7 g per day versus group II [72.6 +/- 28 g per day:ns), without differences in fatty acid intake profile. Total fiber intake did not reach that recommended in both diets but it was higher in group II ( 9.06 +/- 2.7 g per day versus 25.95 +/- 7.12 g per day: P < 0.05). Soluble fiber intake did not reach that recommended in both diets but it was higher in group II (1.7 +/- 0.58 g per day versus 3.5 +/- 0.96 g per day: P < 0.05). Body weight did not change in both groups during treatment. During treatment, in group II a significant change was detected from baseline in LDL-cholesterol and fasting glucose levels. LDL-cholesterol decreased by 12.8% (P < 0.05) and glucose decreased by 12.3% (P < 0.05). No statistical differences were detected among triglycerides, HDL-cholesterol, and insulin levels. CONCLUSIONS: Modest increases in soluble fiber intake in healthy subjects improved LDL cholesterol and glucose levels.
Behall, K. M., D. J. Scholfield, et al. (2006). "Consumption of both resistant starch and beta-glucan improves postprandial plasma glucose and insulin in women." Diabetes Care 29(5): 976-981.
OBJECTIVE: Consumption of a meal high in resistant starch or soluble fiber (beta-glucan) decreases peak insulin and glucose concentrations and areas under the curve (AUCs). The objective was to determine whether the effects of soluble fiber and resistant starch on glycemic variables are additive. RESEARCH DESIGN AND METHODS: Ten normal-weight (43.5 years of age, BMI 22.0 kg/m2) and 10 overweight women (43.3 years of age, BMI 30.4 kg/m2) consumed 10 tolerance meals in a Latin square design. Meals (1 g carbohydrate/kg body wt) were glucose alone or muffins made with different levels of soluble fiber (0.26, 0.68, or 2.3 g beta-glucan/100 g muffin) and three levels of resistant starch (0.71, 2.57, or 5.06 g/100 g muffin). RESULTS: Overweight subjects had plasma insulin concentrations higher than those of normal-weight subjects but maintained similar plasma glucose levels. Compared with low beta-glucan-low resistant starch muffins, glucose and insulin AUC decreased when beta-glucan (17 and 33%, respectively) or resistant starch (24 and 38%, respectively) content was increased. The greatest AUC reduction occurred after meals containing both high beta-glucan-high resistant starch (33 and 59% lower AUC for glucose and insulin, respectively). Overweight women were somewhat more insulin resistant than control women. CONCLUSIONS: Soluble fiber appears to have a greater effect on postprandial insulin response while glucose reduction is greater after resistant starch from high-amylose cornstarch. The reduction in glycemic response was enhanced by combining resistant starch and soluble fiber. Consumption of foods containing moderate amounts of these fibers may improve glucose metabolism in both normal and overweight women.
Devreese, K. and G. Leroux-Roels (1993). "Laboratory assessment of five glucose meters designed for self-monitoring of blood glucose concentration." Eur J Clin Chem Clin Biochem 31(12): 829-837.
We describe a laboratory assessment of five blood glucose meters. The instruments' analytical characteristics under optimum laboratory conditions and examination of potential sources of errors were intercompared. All glucometers produced precise results, and in all but one meter the CV values varied between 1.5% and 6%. CV's for reproducibility and within-day precision of Glucometer Gx were 10.5% and 7.3%. Sample volume, blood incubation time and colour stability of the strip may influence the results of blood glucose measurements with glucose meters. Underloading the sample strip had statistically significant effects on normal blood glucose values for all meters. One Touch II gave also significantly different results when the strip was overloaded. Incubation times shorter or longer than those recommended by the manufacturer influenced the results of all glucose meters. After colour development of the strip, changes were small for Haemo-Glukotest 20-800R strips and Glucotrix, whereas Accutrend glucose strips had to be read immediately following the prescribed incubation time. Comparison of the glucose meter results with those obtained by the hexokinase method showed good correlation coefficients for Reflolux S (r = 0.992), Accutrend (r = 0.988), One Touch II (r = 0.942), Glucometer Gx (r = 0.986) and Glucocard (r = 0.976). Error grid analysis showed that the results of all meters were clinically correct. Variations in haematocrit are known to be a source of errors when blood glucose is determined with a test strip. In the normoglycaemic range the results obtained with Accutrend and Glucocard were not influenced by even extreme haematocrit values. In the high glucose concentration range there was a decrease in blood glucose values with increasing haematocrit for all meters. This error was smaller with Accutrend and Glucocard than with the other meters. Although the new versions of the monitors are easier to use, their analytical performance is not superior to earlier models.
