Adipositas or obesity and overweight in general is a widespread problem in large parts of the world. At the same time, increased health consciousness has stimulated the interest in "keeping the slim line". A large number of different diets have therefore been put on the market aiming at a rapid weight reduction.
Some of these diets must be considered unwarrantable seen from a nutritional point of view as they are based on a very unbalanced intake of nutrients which very quickly will result in deficiency of essential nutrients.
Other diets are based on nutritional preparations being composed in such a way that, at a low calorie content, they supply the necessary proteins, vitamins and minerals. Some of these preparations are in the form of powders containing sources of protein, carbohydrate and fat, and optionally flavouring agents, preservatives, vitamins, minerals and other conventional additives. Before intake, the powders are stirred up in water and then taken as a drink or a gruel. However, the known preparations suffer from a number of deficiencies. Many known powders can only with difficulty be stirred up in water so that the stirred up preparations will have a lumpy and gritty consistency which makes them very unpleasant to take. At the same time, sedimentation occurs very quickly, involving the risk that essential components such as sparingly soluble minerals are not ingested, but remain as a sediment at the bottom of the glass. Finally the preaprations have an unpleasant tang which persists as an after-taste a long time after the preparation has been taken. These disadvantages have the effect that many persons break off the diet too soon.
EP-0 425 423 B1 discloses a process for the preparation of a powdery, low-calorie nutritional preparation, especially for use as the main or sole nutrition in the treatment of adipositas. The preparation has a balanced composition of sources of protein, carbohydrate and fat, and optionally contains flavouring agents, preservatives, vitamins, minerals and other conventional additives. The protein source is a combination of a soy protein concentrate and skimmed milk powder. The soy protein concentrate is a product prepared from shelled soybeans by removing most of the oil and water soluble, non-protein constituents. Soy protein concentrate typically contains 66.0% protein, 17.0% carbohydrate, 6.0% water, 5.6% ashes, 4.0% wood substance, and 1.4% fat. The carbohydrate content is typically present as fibers which are insoluble in water. A typical soy protein concentrate does not contain all the essential amino acids in sufficient amounts. In particular, histidine and tryptophan are limiting amino acids in soy protein concentrate. In order to supply all the essential amino acids, the known nutritional preparation also contains skimmed milk powder as a protein source. However, skimmed milk is not a desirable protein source in certain parts of the world, in particular Southern Europe, Asia and Africa where lactose intolerance is not unusual due to lack of the lactose-degrading enzyme, lactase. Overweight and obesity are often accompanied by an increased fatty content in the blood, and for altering the lipid profile EP-0 425 423 B1 suggests supply of separate capsules comprising fish oil containing polyunsaturated fatty acids along with the nutritional preparation. It would be desirable if the intake of separate fish oil capsules could be avoided for improving the lipid profile. Thus, it would be highly desirable to provide a nutritional preparation which in itself had a beneficial lowering effect upon the lipid level.
As mentioned above, some of the diets presently on the market for weight reduction are based on an unbalanced intake of nutrients, which may result in deficiency of essential nutrients. In particular, a sufficient intake of protein supplying all the essential amino acids is very important in connection with any weightreducing treatment. Typically, 22-36% of the overweight is lean body mass (LBM), which is the fat-free body mass, such as musculature. The loss of proteins from e.g. muscles results in elimination of nitrogen from the body, which can be measured indirectly by determination of the concentration of uric acid in serum. If the concentration of uric acid increases substantially during a weight reduction, the reason may be too much degradation of musculature.
In New England Journal of Medicine, Vol. 333, Aug. 3, 1995, a meta-analysis of the effects of soy protein intake on serum lipids, has been described. In this study, the authors examined the relation between soy protein consumption and serum lipid concentrations in humans. It was found that ingestion of diets containing soy protein, as compared with control diets, was accompanied by a significant reduction in serum concentrations of total cholesterol, LDL-cholesterol and triglycerides. Soy protein intake did not significantly affect serum HDL-cholesterol concentrations. The effect of soy protein intake was dependent upon initial cholesterol concentration. Subjects with normal cholesterol levels had non-significant reductions of 3.3%, and also subjects with mild hypercholesterolemia had non-significant reductions of 4.4%. Only subjects with moderate and severe hypercholesterolemia had significant decreases in cholesterol levels of 7.4% and 19.6%, respectively. The pattern of changes in serum LDL-cholesterol concentrations was similar to the pattern for total cholesterol concentrations. Also changes in serum triglyceride concentrations were significantly related to the initial serum triglyceride concentrations. Various types of soy protein were studied, such as isolated soy protein, textured soy protein, or a combination, and it was found that the type of soy protein did not have any significant effect on the net change in serum cholesterol concentrations. The study did not consider a simultaneous intake of the various types of soy proteins along with soy fibers. This meta-analysis of the effects of soy protein intake on serum lipids found its way to the international press as a sensational finding that soy protein is effective in lowering serum cholesterol, and articles appeared in International Herald Tribune on Aug. 4, 1995, Chicago Tribune on Aug. 3, 1995, and in New York Times on Aug. 3, 1995.
Potter et al., Am J Nutr Clin 1993; 58; 501-6, studied the effects of soy protein consumption with and without soy fiber-on plasma lipids in mildly hypercholesterolemic men. Dietary treatment included 50 g protein and 20 g dietary fiber from soy flour, isolated soy protein/soy cotyledon fiber, isolated soy protein/cellulose, and non-fat dry milk/cellulose in conjunction with a low-fat, low-cholesterol diet. The protein and dietary fibers were prepared as baked products and substituted into the diet. In the experiment using isolated soy protein and soy cotyledon fiber the subjects received per day 50 g isolated soy protein, 50 g other proteins, including 36 g animal and 14 g vegetable protein, carbohydrates corresponding to 55% energy intake, 20 g soy cotyledon fiber, fat corresponding to &lt;30% of total energy content, and 200 mg cholesterol. As a result of the study, it was found that total and LDL-cholesterol concentrations can be lowered significantly in mildly hypercholesterolemic men, which was attributed to the replacement of 50% of dietary protein with soy protein. Similar depressions in blood lipids were noted for isolated soy protein, whether it was consumed in conjunction with soy cotyledon fiber or cellulose fiber. Plasma triglyceride concentrations were unaffected by the various dietary treatments described in the article. The study did not reveal any additive cholesterol-lowering effect of concurrent intake of cotyledon soy fiber with isolated soy protein, and specifically the authors stated: "Whether or not there is an added benefit in lowering blood cholesterol concentrations from increased concurrent intake of soy protein and fiber in humans is not known."
Bakhit et al., J Nutr (in press) 1993, also studied mildly hypercholesterolemic men receiving a baseline diet in combination with four experimental treatments. For each dietary treatment, four types of muffins were prepared and baked, individually packaged, frozen and stored at -20.degree. C. until distributed to subjects on a wveekly basis. The four muffins containing appropriate test proteins and fibers were added to the basal diet replacing a total of 2.51 MJ of the subject's normal intake. The test proteins used were isolated soy protein and casein as sodium casenite. Fibers were soy cotyledon fibers and cellulose fibers. Protein and fiber were incorporated into the muffins to provide 25 g of protein and 20 g of dietary fiber daily in four muffins. The weight ratio between protein and fibers were in all cases 1.25, and the amount of protein corresponded to 20% of the total energy content. The goal of the study was to evaluate the ability of a relatively low level of soybean protein intake (25 g.apprxeq.5% of energy intake per day) with and without soy cotyledon fibers, to decrease plasma lipid concentrations when consumed along with a typical low-lipid diet. As a result, it was found that adding of 25 g of soybean protein to a low-fat, low-cholesterol diet lowers total cholesterol concentrations in men with elevated blood lipids. In subjects having lower blood cholesterol concentrations (&lt;5.7 mmol/l), this level of soybean protein intake did nok influence blood lipids, and it was suggested that plasma lipids may even be elevated in some subjects following soybean ingestion. Also other previous studies have found that in general individuals with pre-existing hypercholesterolemia respond to soybean protein, wheres individuals with normal cholesterol values do not. Bakhit et al. did not observe an additive effect of concurrent ingestion of soybean protein and soybean fiber. According to the authors, soybean protein may affect cholesterol metabolism directly, possible via modulation of endocrine status, whereas soybean fiber most likely acts by interrupting enterohepatic circulation of bile.
In conclusion, the above-discussed studies of Potter et al. and Bakhit et al. did not find any serum lipid lowering effect in subjects having a normal blood cholesterol concentration below 5.7 mmol/l.
High serum levels of cholesterol cause disease and death by contributing to the formation of atherosclerotic plaques in arteries throughout the body. In order to reduce high serum cholesterol levels, subjects may be put on a low fat, low cholesterol diet or may be treated with medicaments such as statins, or a combination of both. The statins selectively inhibit HMG-CoA-reductase which is the controlling enzyme in the cholesterol synthesis. The enzyme increases the formation of LDL receptors and among other hereby decreases the level of LDL-cholesterol in the blood. Once the serum level of cholesterol has been lowered to a normal value, it will be desirable to avoid further medication by, subjecting the individual to a diet which can retain serum levels of cholesterol at a normal value and more preferably lower the serum cholesterol concentration below a value of 5.7 mmol/l. Also many physicians find that a serum cholesterol level of 5.7 mmol/l is too high, especially in subjects with a history of cardiovascular disease, where it is medically proven that a lower cholesterol level than 5.7 mmol/l reduces myocardial infarction and deaths considerably. Thus, there is a need for a composition which can lower serum cholesterol concentrations in subjects having a normal serum lipid concentration.