Enteral nutrition and medical foods having soluble fiber

This application relates to low-viscosity enteral and medical foods which contain fiber, especially soluble fiber, and to the use of these foods to maintain healthy colon cells and to prevent bacterial sepsis.

Nutritionally complete liquid diets are often administered to patients either orally or through feeding tubes (enterally). It has been noted that a frequent side-effect of this type of feeding is diarrhea. Diarrhea can lead to fluid and/or electrolyte imbalance and malnutrition. Further, it can cause discomfort and sanitation problems, require considerable staff time, thus resulting in increase patient care costs.

Secondly, it has also been noted that many critically ill patients develop bacterial sepsis, a leading cause of death in intensive care units.

Feeding compositions are currently known which contain soy polysaccharide fiber. Soy polysaccharide fiber is considered to be an insoluble fiber. A recent study questioned the effectiveness of such a formulation in preventing diarrhea. See, e.g. Frankenfield et al., 1989. "Soy-Polysaccharide Fiber: Effect on Diarrhea in Tube-fed, Head Injured Patients" Am. J. Clin. Nutr. 50:533-538.

DESCRIPTION OF THE INVENTION

It has been found that adding a soluble fiber supplement to an otherwise nutritionally complete liquid food composition can prevent both diarrhea and bacterial sepsis while retaining the low viscosity character of the food composition. This invention, therefore relates to food compositions comprising such soluble fiber, and to the use of such food compositions to prevent both diarrhea and bacterial sepsis.

As used throughout the specification and claims, the term "nutritionally complete" refers to a feeding composition which contains carbohydrates, proteins, essential fatty acids, vitamins, and minerals in such amounts that a person can ingest only that composition for a prolonged period of time and not suffer any malnutrition. The composition may have water added to it such that the composition is in liquid form and suitable for drinking or for use with a tube-feeding apparatus. Alternatively, the composition may be in dry form.

Numerous feeding compositions are known and commercially available, including those commercially available from Sandoz Nutrition Corp. under the trademarks RESOURCE.RTM. and ISOSOURCE.RTM. (both liquid formulations) and STRESSTEIN.RTM. (dry product). These compositions typically provide approximately 20-70% of calories in the form of carbohydrates, 13-30% of calories in the form of protein, 20-50% of calories as lipid (which includes essential fatty acids) as well as vitamins, minerals, and optionally water, flavoring agents, fillers, binders, coloring agents, coating materials, or other nutritional supplements.

As used throughout the specification and claims, the term "soluble fiber" refers to fibers which are able to undergo fermentation in the colon to produce short chain fatty acids (SCFA). Examples of soluble fibers are: pectin, guar, hydrolyzed guar, and gum arabic. "Insoluble fibers" are those fibers which will not go into solution. Examples of insoluble fibers include soy polysaccharides and brans.

It has been found in accordance with this invention that certain soluble fibers can be added to feeding compositions, and result in a composition which prevents diarrhea and bacterial sepsis. The soluble fiber may be the only fiber in the feeding composition, i.e. it may be added to a feeding composition which previously did not contain any fiber, or it may replace fiber which previously was present in the feeding composition. Alternatively, the soluble fiber may be an addition to an insoluble fiber present in the feeding composition.

The soluble fiber may be chosen from numerous known soluble fibers, including locust beam gum, xanthan gum, guar gum, hydrolyzed guar gum, and pectin. The preferred fibers, for numerous reasons set forth below are hydrolyzed guar gum and pectin; hydrolyzed guar gum being the most preferred.

One primary requirement, especially for enteral compositions, is that the soluble fiber should not substantially increase the viscosity of the product above approximately 50 cp, and it is preferred that the viscosity remain under 25 cp, more preferably 10-25 cp. As used throughout the specification and claims, the term "low viscosity" means a viscosity of less than 25 cp.

A particularly preferred hydrolyzed guar gum is commercially available from Taiyo Kagaku Co, Ltd. (Japan) under the trade name Sun Fiber. Sun Fiber is a purified hydrolyzed guar gum prepared by hydrolyzing guar gum with .beta.-mannase from Aspergillus niger. Prior to hydrolysis, the molecular weight of guar gum is approximately 200,000; after hydrolysis it is 20,000-30,000. For use in accordance with this invention, the molecular weight range of the hydrolyzed guar gum may vary, as long as the viscosity of the finished product does not exceed 50 cp.

The amount of soluble fiber added to a feeding composition may vary depending on the needs of the patient and whether the composition is to be taken orally or enterally. Thus the fiber content of the composition may vary according to the amount of composition intended to be ingested per day. It is generally preferred that the soluble fiber content of the composition be adjusted so that the patient receives approximately 10-60 g/day soluble fiber, and more preferably approximately 20 g/day soluble fiber.

It is well known that colon cells nourished by exclusively liquid diets may atrophy. This atrophy manifests itself in a breaking down of the gut mucosal barrier, allowing gram negative bacterial and/or bacterial endotoxin produced by these bacteria to invade the patient's circulatory system, causing shock. It has been found in accordance with this invention, that providing colon cells with a source of fiber which can be fermented into butyric acid, maintains health of the colon cells and the intactness of the gut mucosal barrier, reducing the incidence of septic shock. In addition, the healthy colon cells can retain minerals better, and are able to reabsorb water. Pectin and hydrolyzed guar gum are particularly good sources of butyric acid, as detailed in Example 1, below.

Another benefit which can be realized by the addition of either hydrolyzed guar gum or pectin is that diarrhea can be controlled.

This invention is further illustrated in the following non-limiting examples.

EXAMPLE 1

Fermentability of Fibers

Various fibers are suspended in water and buffered to neutrality. A sample of microorganisms normally found in the colon is added and fermentation is allowed to occur for 24 hours at 37.degree. C. in a mannometer. The resulting ferment is analyzed for the amount of butyric acid per gram of fiber. Results are presented below:

______________________________________ Millimoles of Butyric Acid per Fiber Gram of Fiber ______________________________________ Hydrolyzed Pectin 0.38 Pectin 0.28 Sun Fiber (hydrolyzed guar) 1.45 Guar 0.86 Gum Arabic 0.22 Soy Polysaccharide 1.16 Polydextrose 0.16 ______________________________________

As can be seen from the above, the hydrolysis of both pectin and guar improves the fermentability of these fibers. The results for soy polysaccharide may be misleadingly high due to a starch associated with the insoluble fiber. In a mammalian system, the soy polysaccharide could be expected to yield much less butyric acid.

EXAMPLE 2

Oral Supplement Containing Soluble Fiber

An oral supplement is made using the following ingredients.

______________________________________ INGREDIENT FORMULA PERCENTAGE ______________________________________ Deionized Water 75.51 Maltrin 200 (maltodextrin) 10.47 Sugar--Canners grade 3.66 Corn Oil 3.40 Sodium Caseinate 2.97 *Mineral premix 0.38 Calcium Caseinate 0.48 **Gum premix 0.02 Soy Protein isolate 0.48 ***Vitamin premix 0.07 Artificial Vanilla Flavor 0.18 Magnesium Chloride 0.18 Lecithin 0.17 Potassium Citrate 0.26 Choline Chloride 0.07 Potassium Hydroxide 0.05 Natural & Artificial 0.01 Vanilla Flavor Vitamin E Oil 0.12 Potassium Chloride 0.10 Antifoam 0.02 Soluble Fiber 1.4 100.00 ______________________________________ *Mineral premix contains: Tricalcium phosphate 0.20765% Sodium citrate 0.16730 Zinc sulfate 0.00538 Ferrous sulfate 0.00330 Copper gluconate 0.00100 Manganese sulfate 0.00076 Potassium iodide 0.00036 **Gum premix contains: Caragennan 0.01440% Carrageenan 0.00960% ***Vitamin premix contains: Ascorbic acid 0.05616% Niacinamide 0.00230 Biotin 0.00197 Vitamin A 0.00178 Calcium pantothenate 0.00119 Cyanocobalamin B12 0.00098 Vitamin K 0.00070 Thiamin hydrochloride 0.00035 Pyridoxine hydrochloride 0.00035 Folic acid 0.00029 Vitamin D 0.00028 Riboflavin B2 0.00022

Oil is heated to 155.degree.-165.degree. F. Wet salts and gum premix is added to the deionized water which is heated to 140.degree. F. Next, the maltrin, sugar, caseinates, and soy protein is added. The soluble fiber source is then added. The soluble fiber may be either hydrolyzed guar gum or pre-treated pectin (at least 0.25%, which equals at least 15 g per 2,000 calories). pH is adjusted to 6.8. Next, the potassium citrate and the mineral premix are added and temperature is increased to 150.degree. F. The hot oil is then added and heated to 165.degree. F. The mixture is then homogenized. Vitamin premix and flavor is added and mixed thoroughly. The mixture is then heat processed and packaged aseptically.

EXAMPLE 3

Replacing Insoluble Fiber with Soluble Fiber

A currently available product, FIBERSOURCE.RTM., contains soy polysaccharide which is insoluble fiber. Hydrolyzed guar gum may be used to replace the soy polysaccharide or may be added in addition to the soy polysaccharide. Below is an example where the hydrolyzed guar gum replaces soy polysaccharide on a one-to-one basis, but other ratios may be used. If one wished to replace soy polysaccharide with hydrolyzed pectin, a different emulsifier system is needed.

______________________________________ INGREDIENT % FORMULA ______________________________________ Deionized water 73.29 Maltrin 100 (maltodextrin) 11.33 Maltrin 200 (maltodextrin) 4.500 Sodium Caseinate 3.227 Medium Chain Triglyceride Oil 1.994 Canola Oil 1.779 Sun Fiber 1.319 Calcium Caseinate 1.209 Potassium Citrate 0.4050 Vanilla Flavor 0.1000 Sodium Citrate 0.2025 Magnesium Chloride 0.1829 Tricalcium Phosphate 0.1411 *H.sub.2 O Vitamin premix 0.06329 Potassium Chloride 0.08406 Polyglycerol esters of 0.06136 fatty acids **Multimineral premix 0.02859 Choline Chloride 0.04522 ***Fat/Vitamin premix 0.00288 Vitamin E Oil 0.003600 Dipotassium Phosphate 0.03283 100.0 ______________________________________ *H.sub.2 O Vitamin Premix contains: Sodium ascorbate 0.05522% Niacinamide (B.sub.3) 0.003280 Calcium pantothenate 0.002100 Cyanocobalamin (B.sub.12) 0.001440 Thiamin hydrochloride 0.000450 Pyridoxine hydrochloride 0.000420 Riboflavin (B.sub.2) 0.000300 Biotin 0.000050 Folic acid 0.000030 **Multimineral premix contains: Selenium yeast 0.01019 Chromium east 0.005150 Zinc sulfate 0.004910 Ferrous sulfate 0.004910 Manganese sulfate 0.001210 Sodium molybdate 0.001100 Copper gluconate 0.001100 Potassium iodide 0.000020 ***Fat/vitamin premix contains: Vitamin A palmitate 0.001720 Vitamin K 0.000780 Vitamin D.sub.3 0.000380

EXAMPLE 4

Oral Supplement with Soluble Fiber

The following composition is suitable as an oral supplement. Although oral supplements are often viscous, this formulation retains a low viscosity. The addition of 1% hydrolyzed guar gum leads to a high viscosity product which, while not wishing to be bound by theory, may be due to an interaction between the protein and hydrolyzed guar gum. However, it has been found that at a somewhat lower amount of fiber, the supplement will remain its low viscosity.

______________________________________ INGREDIENT % FORMULA ______________________________________ Deionized Water 76.5541 Sugar 14.5 Whey Protein Concentrate 3.88 Sunflower Oil 2.10 Corn Syrup Solids 1.17 Phosphoric Acid (75%) 0.315 Citric Acid 0.190 Flavor/Color 0.100 Polyglycerol Ester 0.050 Sucrose Fatty Acid Ester 0.050 Cysteine 0.050 *Vitamin and Mineral Premix 0.79089 Soluble Fiber 0.25 100.00 ______________________________________ *Premix contains: Magnesium gluconate 0.400 Calcium chloride 0.190 Choline bitartrate 0.121 Ascorbic acid 0.056 Vitamin E acetate 0.00542 Zinc sulfate 0.00537 Ferrous sulfate 0.003299 Niacinamide 0.002298 Vitamin A palmitate 0.001772 d-Calcium pantothenate 0.001195 Cyanocobalamin 0.000981 Copper gluconate 0.000882 Manganese sulfate 0.000759 Vitamin K.sub.1 0.000653 Thiamine hydrochloride 0.000350 Pyridoxine hydrochloride 0.000348 Vitamin D 0.000283 Riboflavin 0.000220 Folic acid 0.000032 Biotin 0.000020 Potassium iodide 0.000018

The emulsifier is dissolved in hot water. Protein, sugar, maltodextrin and hydrolyzed guar gum are then added. Next, oil is added, then pre-blended acids, vitamins and minerals. The mixture is heated to 160.degree. F., and then flavors and colors are added. The mixture is then homogenized, heat processed, and packaged aseptically.

EXAMPLE 5

Effects of Dietary Soluble and Insoluble Fiber on the Intestinal Flora, Intestinal Histology and Bacterial Transaction in Mice

1. Effect on Bacteria

Four groups of mice are fed either normal mouse chow, a commercially available liquid food composition (abbreviated Liq), the liquid composition supplemented with 2.5% soy fiber (Liq+S), or the liquid composition supplemented with 2.5% hydrolyzed guar gum (Liq+G). After 14 days, the type and amound of cecal bacteria are measured. Results are presented in table 5A below. "Wt" is average (n=24) weight gain in grams in 14 days. Numbers given under the bacterial columns represent the average and standard error (log.sub.10) of cecal bacteria per gram (n=8)

TABLE 5A ______________________________________ Aerobic + Aerobic + facultative facultative Strict Diet Wt gram-neg. bacilli gram-pos. bacteria Anaerobes ______________________________________ Chow 3.5 4.3 .+-. 0.9 8.0 .+-. 0.2 9.5 .+-. 0.1 Liq. 4.5 .sup. 7.6 .+-. 0.2.sup.a 7.8 .+-. 0.2 9.7 .+-. 0.2 Liq + S 4.1 .sup. 6.6 .+-. 0.2.sup.b 8.0 .+-. 0.2 9.9 .+-. 0.2 Liq + G 4.7 6.2 .+-. 0.4 8.4 .+-. 0.1 10.2 .+-. 0.1.sup.b ______________________________________ .sup.a Significantly increased compared to chowfed mice, P < 0.01 by ANOV .sup.b Significantly increased compared to chowfed mice, P < 0.05 by ANOV

The table shows that the liquid diet and the liquid diet supplemented with soy fiber both significantly increased the amount of aerobic and facultative gram-negative bacteria. Gram-negative bacteria are those which can cause bacterial sepsis if they or the endotoxins produced by them translocate into the bloodstream. No such increase was observed in the liquid food supplemented with the hydrolyzed guar. The strict anaerobe count was increased with the liquid+hydrolyzed guar, but these bacteria are considered more "benign" than the aerobic gram-negative bacteria.

2. Translocation of Bacteria

Septic shock occurs after bacteria or their endotoxins enter the bloodstream. One of the first steps in this process is the translocation of cecal bacteria to the mesenteric lymph nodes (MNL). As liquid feeding tends to increase the amount of gram-negative bacteria, it is important to maintain the blood-mucosal barrier to eliminate translocation. The effect of diet on this translocation was investigated, and results are presented below in Table 5B. Each group of mice was fed chow, Liq, Liq+S, or Liq+G as described above for 14 days.

TABLE 5B ______________________________________ No. of mice with viable bacteria in MLN(%) No. and identity of bacteria Diet Total No. mice.sup.a in the MLN of individual mice ______________________________________ Chow 3/24 (13%) 10 E. coli 20 E. coli 450 Lactobacillus sp. Liq 1/24 (4%) 20 coagulase-negative staphylococci Liq + S 2/24 (8%) 10 Lactobacillus sp. 40 Enterobacter sp. Liq + G 1/24 (4%) 20 E. coli ______________________________________ .sup.a Chi-square analysis indicates no significant differences between chowfed mice and mice fed Liq, Liq + S, or Liq + G.

Thus, as shown in the table above, addition of the hydrolyzed guar fiber did not have any adverse effects on the translocation of bacteria into the MNL.

3. Effect of Diet on Bacteria in Endotoxin Lipopolysaccharide-Treated (LPS) Mice

Each group of mice was fed as previously described and was given 200 .mu.g i.p. injection of endotoxin lipopolysaccharide, the toxin which is involved in septic shock. Results are presented in Table 5C below. Abreviations and units are the same as those used in Table 5A.

TABLE 5C ______________________________________ Aerobic + Aerobic + facultative facultative gram-neg. gram-pos. Strict Diet Wt. bacilli bacteria Anaerobes ______________________________________ Chow 0.3 9.0 .+-. 0.1 8.4 .+-. 0.2 9.7 .+-. 0.2 Liq 1.8 9.7 .+-. 0.3 .sup. 9.4 .+-. 0.3.sup.a 10.2 .+-. 0.2 Liq + S 2.3 9.2 .+-. 0.2 8.7 .+-. 0.2 9.7 .+-. 0.2 Liq + G 1.2 9.1 .+-. 0.2 8.9 .+-. 0.2 10.2 .+-. 0.1 ______________________________________ .sup.a Significantly increased compared to chowfed mice P < 0.1 by ANOVA

None of the liquid diets were seen to have an adverse effect on the intestinal flora of LPS-treated mice. As expected, number of enteric gram-negative bacteria (primarily E. coli) increased with the intraperitoneal LPS treatment for all treatment groups.

4. Translocation of Bacteria to MLN in LSP-Treated Mice

Mice were fed as described supra and treated with LPS as described supra. The number and identity of bacteria found in the MLN was determined. Results are presented in Table 5D, below.

TABLE 5D ______________________________________ No. mice with viable bacteria No. and identity of viable in MLN(%) Total bacteria in MLN of individual Diet No. of mice mice ______________________________________ Chow 14/23 (61%).sup.a 60 E. coli 10 E. coli 60 E. coli 10 P. mirabilis + 150 Lactobacillus sp. 10 E. coli 10 E. coli 30 E. coli 100 E. coli 10 E. coli 80 E. coli 60 Enterobacter sp. 10 E. coli 10 Enterobacter sp. 20 E. coli Liq 21/24 (88%) 10 E. coli 20 Enterococcus sp. 70 Enterococcus sp. 50 Enterococcus sp. 10 Enterobacter + 650 Enterococcus sp. 10 Enterococcus sp. 10 E. coli + 10 Enterobacter sp. 20 Enterococcus sp. 120 Enterococcus sp. 90 E. coli 110 E. coli 20 Enterococcus sp. 10 Lactobacillus sp. 20 Enterococcus sp. 30 Enterococcus sp. 30 E. coli 10 E. coli + 10 Enterococcus sp. 150 Enterococcus sp. 10 E. coli 90 Enterococcus sp. Liq + S 12/24 (50%).sup.b 20 E. Coli 10 coagulase-negative staphylococci 40 E. coli 40 E. coli 110 Enterococcus sp. 10 Lactobaccilus sp. 10 E. coli 10 E. coli + 70 S. aureus 40 E. coli 20 Enterobacter sp. 10 E. coli 10 Enterococcus sp. Liq + G 9/24 (42%).sup.c 10 E. coli 40 E. coli + 30 Enterococcus sp. 10 Enterobacter sp. 70 E. coli + 20 Enterococcus sp. 30 E. coli 60 Enterobacter sp. + 130 Enterococcus sp. 40 Enterobacter sp. + 10 Enterococcus sp. 20 Enterobacter sp. + 60 Enterococcus sp. 30 Enterococcus sp. ______________________________________ .sup.a One mouse died out of 24 mice .sup.b Significantly decreased compared to mice fed Liq, P < 0.05 by Chisquare with continuity correction. .sup.c Significantly decreased compared to mice fed Liq, P < 0.01 by Chisquare with continuity correction.

Compared to chow fed mice, Liq+S and Liq+G have an improvement in preventing the translocation of intestinal bacteria to the mesenteric lymph nodes of mice. Compared to chow-fed mice, Liq appeared to increase the incidence of bacterial translocation somewhat (P=0.08). However, the supplementation with soy or hydrolyzed guar fiber had the beneficial effect of significantly decreasing the incidence of translocation of bacteria.