Sugar Beet Fiber in Formula Diet Reduces Postprandial Blood Glucose, Serum Insulin and Serum Hydroxyproline

Sugar beet ®ber in formula diet reduces postprandial blood glucose, serum insulin and serum hydroxyproline

I Thorsdottir1, H Andersson2 and S Einarsson3

1Unit for Nutrition Research, National University Hospital & Department of Food Science, University of Iceland, IS-101 Reykjavik, Iceland; 2Department of Clinical Nutrition, Institute of Internal Medicine, University of GoÈteborg, Sahlgren's Hospital, S-413 45 GoÈteborg, Sweden; and 3Environmental and Food Agency of Iceland, P.O. Box 8080, IS-128 Reykjavik, Iceland

Objective: The objective of the study was to investigate the effects of sugar beet ®ber in formula diet on blood glucose, serum insulin and serum hydroxyproline in humans. Design: Two formula test meals with and without 7 g of sugar beet ®ber, namely 5.1 g total dietary ®ber, were ingested on two mornings, in random order, by the subjects. Setting: The test meals were served in a clinic to the subjects after a 12 h fast. Subjects: Fifteen healthy male human volunteers (mean age 25 y, range 21±42) registered to participate in the study after an announcement. Methods: The test meals of formulas contained similar amounts of nutrients and gave total energy of 1778 kJ (425 kcal). Blood samples were drawn before and after the test meals. The total test time from the start of ingestion of the meal was 155 min. Results: The formula with sugar beet ®ber reduced the postprandial blood glucose response (P < 0.05), serum insulin response (P < 0.025) and serum hydroxyproline response (P < 0.025), compared with the formula without ®ber. Conclusion: Sugar beet ®ber in a formula could thus reduce hyperglycemia in enteral nutrition and be useful in therapeutic liquid and formula diets. Sugar beet ®ber was shown to tolerate preparation for canning well, namely homogenization and heating, and to be capable of diminishing the glycemic responses in the relatively small amount used. Sponsorship: Swedish Council for Forestry and Agricultural Research (L24 and L39), the Icelandic Council of Science, and Semper AB, Sweden. Descriptors: sugar beet ®ber; blood glucose; insulin; hydroxyproline; viscosity; enteral nutrition

Introduction hydroxyproline in humans. The viscosity of the formula was measured at different pH levels prior to the study, as Hyperglycemia is a common sequela to enteral nutrition processing the ®ber may alter its properties and therefore (Vanlandingham et al, 1981). With regard to arti®cial change its ability to affect human physiology. nutrition of diabetic patients the modi®cation of glucose absorption to reduce hyperglycemia is of greatest interest (Scheppach et al, 1990). Soluble ®ber preparations, such as Methods guar gum, are known to increase viscosity and reduce postprandial glycemia in humans. However the effects Experimental subjects were lost when a guar-containing formula was heated and Fifteen healthy male human volunteers (mean age 25 y, homogenized to prepare the formula for canning (Thors- range 21±42) were served two different test meals, in dottir et al, 1989). In that study the non-essential amino randomized order, on two separate mornings after a 12-h acid, hydroxyproline, was used as a reference substance for fast. Details about the subjects' selection criteria and small bowel absorption (Thordottir et al, 1989). Hydroxy- written information they were provided have been proline was added to the test meals and serum concentra- described previously (Thorsdottir et al, 1989). The study tions measured. was approved by the Local Ethical Committees at Sahl- Sugar beet ®ber is isolated from the sugar beet pulp and gren's Hospital and the National University Hospital of contains both soluble and insoluble dietary ®ber. If sugar Iceland. beet ®ber can tolerate the preparation procedure, it can be useful in liquid and enteral diets. Test meals Sugar beet ®ber's suitability in formula and liquid The test meals consisted of 425 mL of two formulas, one nutrition has not been studied. The aim of the present ordinary formula diet without dietary ®ber and the other study was to investigate the effects of sugar beet ®ber in made of the same formula with the addition of sugar beet formula diet on blood glucose, serum insulin and serum ®ber (Fibrex, Swedish Sugar Corp., ArloÈv, Sweden) (Semper sond, Stockholm, Sweden). Each test meal gave 1778 kJ (425 kcal), 19.1 g protein (18% of energy), 14.9 g fat (33% of energy) and 51 g of non-®ber carbohydrates Correspondence: Dr I Thorsdottir. Received 7 February 1997; revised 9 September 1997; accepted (49% of energy) from ingredients described earlier (Thors- 15 September 1997 dottir et al, 1989). The ®ber formula test meal included Sugar beet ®ber in formula diet I Thorsdottir et al 156 7.0 g of sugar beet ®ber preparation, corresponding to 5.1 g Discussion of dietary ®ber, of which 3.7 g were soluble ®ber, 2.1 g The present study showed that sugar beet ®ber included in a hemicellulose and 1.6 g pectin (Persson, 1986; Hagander et formula diet diminished postprandial blood glucose, insulin al, 1986). The amino acid L-4-hydroxyproline (3.00 g and hydroxyproline levels in healthy humans. It showed dissolved in 3 mL of water) (Merck, Darmstadt, Germany) that a small dose of dietary sugar beet ®ber, namely 5.1 g, was added to the test meals immediately before ingestion. of which 3.7 g were soluble hemicellulose and pectin, could The viscosity of the meals was measured at 37C (Rheomat reduce glycemic response. 30, Contraves AG, ZuÈrich, Switzerland) at neutral and The results of the present study also show the beet ®ber's lowered pH. Sugar beet ®ber in the formula diet increased tolerance for preparation by heating and homogenization for the viscosity of the meal, especially at low pH levels. canning. Earlier we found that guar gum ®ber could not be Lowering the pH of the formula without ®ber to pH 4 used after such treatment as the property of the ®ber was and pH 3 had no effect on the viscosity as previously destroyed by the procedure (Thorsdottir et al, 1989). reported (Thorsdottir et al, 1989) but gave a higher vis- Soluble dietary ®bers have glycemic-lowering effects cosity of the formula diet with beet ®ber, which increased that have been related to their ability to increase intragastric to 500±100 mPa 6 s, at shear rate 40±500 s71. viscosity and reduce the gastric emptying rate (Benini et al, 1995; Thorsdottir et al. 1989; Thorsdottir et al, 1991). A Blood sample analysis slower gastric emptying rate may be the mechanism con- Blood samples were taken from an intravenous catheter trolling the glycemic-lowering effects of sugar beet ®ber. before (t 0) and 15 min, 25 min, 35 min, 45 min, 55 min, In addition to the reduction of hyperglycemia sugar beet 65 min, 75 min, 95 min, 125 min and 155 min after the start ®ber may be used in liquid and formula diet for other of ingestion of the test meals. Blood glucose was analyzed physiological and therapeutic effects. Lampe et al (1993) by the glucose oxidase method (Merck, Darmstadt, Ger- and Langkilde et al (1993) have shown bene®cial gastro- many), serum insulin by a radioimmunoassay technique intestinal effects of sugar beet ®ber that can diminish the (Diagnostic Products, Los Angeles, CA) and serum hydro- risk of diarrhea in patients receiving enteral nutrition. Sugar xyproline by HPLC (Thorsdottir, 1989). beet ®ber has also been shown to be capable of lowering blood lipids in individuals with hypercholesterolemia Statistical analysis (Frape & Jones, 1995). The Student's paired t-test was used for comparison of the two test meals, and a P < 0.05 was considered signi®cant. The results are presented as mean Æ s.e.m. The Excel Conclusions program (Microsoft Excel 5.0 for Windows; Microsoft Corporation, Microsoft Way Redmond, WA) was used The effects of sugar beet ®ber may be useful in therapeutic for the calculations. liquid and formula diets when the hypoglycemic and other physiological effects of the ®ber are considered important. Results AcknowledgementsÐThe authors thank S Lindstrand and SK Arnadottir The mean ingestion time was 5 min (range 4±6 min) for for skillful technical assistance. both formula test meals and fasting values before ingestion were similar. The mean Æ s.d. fasting blood glucose, serum insulin and hydroxyproline were 4.3 Æ 0.3 mmol=L, 41.6 Æ References 23.7 pmol=L and 12 Æ 6 mmol=L, respectively. Benini L, Castellani, G, Brighenti F, Heaton KW, Brentegani MT, The formula test meal with sugar beet ®ber gave a Casiraghi MC, Sembenini C, Pellegrini N, Fioretta A, Minniti G, Porrini signi®cantly lower rise in postprandial blood glucose M, Testolin g & Vantini I (1995): Gastric emptying of a solid meal is (P < 0.05), serum insulin (P < 0.025) and hydroxyproline accelerated by the removal of dietary ®bre naturally present in food. Gut (P < 0.025) than the formula test meal without ®ber. The 36, 825±830. Frape, DL & Jones AM (1995): Chronic and postprandial responses of Table shows that sugar beet ®ber lowered the incremental plasma insulin, glucose and lipids in volunteers given dietary ®bre areas over 2 h for glucose and insulin by 19% and 21%, supplements. B. J. Nutr. 73, 733±751. respectively, and over 1 h for glucose, insulin and hydroxy- Hagander B, Asp N-G, Efendic S, Nilsson-Ehle P, Lundquist I & SchersteÁn proline by 24, 23 and 21%. B (1986): Reduced glycemic response to beet-®bre meal in in non- insulin-dependent diabetics and its relation to plasma levels of pancrea- tic and gastrointestinal hormones. Diabetes Res. 3, 91±96. Table 1 Postprandial glucose, insulin and hydroxyproline increase after Lampe JW, Wetsch RF, Thompson WO & Slavin JL (1993): Gastro- formula test meals with or without 7 g sugar beet ®ber, namely 5.1 g intestinal effects of sugarbeet ®ber and wheat bran in healthy men. Eur. dietary ®bera J. Clin. Nutr. 47, 543±548. Langkilde AM, Anderson H & Bosaeus I (1993): Sugar-beet ®bre Meals increases cholesterol and reduces bile acid excretion from the small bowel. Br. J. Nutr. 70, 757±766. Characteristic Without beet ®ber With beet ®ber Persson K (1986): Kemisk karakterisering av bet®ber. Livsmedelsteknik 12, 454±455. Incremental area under the 2 h curves Scheppach W, Burghardt W, Bartram P & Kasper H (1990): Addition of diet- glucose mmol=L 1.59 Æ 0.21 1.28 Æ 0.22 ary ®ber to liquid formula diets: The pros and cons. JPEN 14, 204±209. insulin pmol=L 516 Æ 57 408 Æ 38 Thorsdottir, I, Alpsten M, Anderson H & Einarsson S (1989): Dietary guar Incremental area under the 1 h curve gum effects on postprandial blood glucose, insulin and hydroxyproline glucose mmol=L 1.31 Æ 0.15 0.99 Æ 0.14 in humans. J. Nutr. 119, 1925±1931. insulin pmol=L 356 Æ 42 273 Æ 31 Thorsdottir, I, Alpsten M, Holm G, Sandberg AS, & ToÈlli J (1991): A Hydroxyproline mmol=L 84.2 Æ 8.1 66.7 Æ 6.6 small dose of soluble alginate-®ber affects postprandial glycemia and gastric emptying in humans with diabetes. J. Nutr. 121, 795±799. aValues are means Æ s.e.m.; n 15, Student t-test: P < 0.025 for post- Vanlandingham S, Simpson S, Daniel P & Newmark SR (1981): Metabolic prandial insulin and hydroxyproline increase P < 0.05 for postprandial abnormalities in patients supported with enteral tube feeding. JPEN 5, glucose increase. 322±325.