Yogurt Diet Research Articles

Influence of dairy matrix on the prebiotic effects of inulin related to gut metabolic activity and bone health.

Inulin is a well-recognized prebiotic ingredient established to modulate the gut microbiome and its metabolic functionality. However, little is known about how the food matrix interacts with the prebiotic efficacy of inulin. The aim of the present study was to investigate the interaction between the food matrix (milk vs. yogurt) and the gut microbiome modulatory effects of inulin and its influence on calcium bioavailability as reflected in bone mineralization. For this purpose, a 6-week dietary intervention was conducted in healthy young growing male rats (n = 36) which received a diet matrix that included: (1) milk, (2) milk supplemented with 5% inulin, (3) yogurt, or (4) yogurt supplemented with 5% inulin. All diets were limited in calcium content and provided a daily intake of 46 mg calcium per rat. We found that inulin fortification of a yogurt diet exerted a larger effect on gut fermentation as reflected in pH and the generation of acetate in the distal part of the intestine and feces compared with inulin fortification of milk. Inulin was also associated with a higher acetate concentration in plasma when supplied in yogurt compared with milk. No effects of inulin supplementation were found on bone parameters. In conclusion, the present study suggested that the prebiotic efficacy of inulin is higher when supplied in a fermented dairy product than milk. However, neither adding inulin to yogurt or milk affected bone mineralization or the bone structure.

Quality characteristics of yogurts fermented with short-chain fatty acid-producing probiotics and their effects on mucin production and probiotic adhesion onto human colon epithelial cells

Probiotics can ferment nondigestible carbohydrates and produce short-chain fatty acids (SCFA; acetate, propionate, and butyrate) in the human colon. In this study, the levels of SCFA were determined in the following yogurts fermented with different combinations of probiotics: (1) cocultures of Streptococcus thermophilus and Lactobacillus bulgaricus (control, C); (2) S. thermophilus, L. bulgaricus, and Bifidobacterium bifidum (C-Bb); (3) S. thermophilus, L. bulgaricus, and Lactobacillus acidophilus (C-La); and (4) S. thermophilus, L. bulgaricus, and Lactobacillus gasseri (C-Lg). Results showed that the acetate levels were significantly higher in C-Bb, C-La, and C-Lg yogurts than in C yogurt. Fermentation and physicochemical characteristics of all yogurts were identical. Treatment of mucus-secreting colon epithelial cells (HT29-MTX) with C-Bb, C-La, and C-Lg yogurt supernatants resulted in an increase in the expression of MUC2 and CDX2 and the production of mucin proteins. The adhesion of probiotics onto HT29-MTX cells increased following treatment with C-Bb, C-La, and C-Lg yogurt supernatants. Our data suggest that a yogurt diet rich in acetate improves the protective function of the intestinal epithelium.

Hepatoprotective effects of synbiotic soy yogurt on mice fed a high-cholesterol diet.

The role of probiotic yogurt in the prevention and treatment of hypercholesterolemia has attracted global attention. Mounting evidence has indicated that probiotics and prebiotics improve lipid metabolism by lowering low-density lipoprotein cholesterol concentration in plasma of hypercholesterolemic patients. The present study aimed to develop synbiotic soy yogurt that had a greater cholesterol-lowering effect in hypercholesterolemic mice compared with control soy yogurt. Synbiotic soy yogurt was prepared using soy milk and synbiotic capsule containing LactoBacil Plus (SCLBP) probiotic cultures and fructo-oligosaccharide. Synbiotic soy yogurt was analyzed for proximate composition and microbiological and antioxidative properties during storage periods of 28 d. To study hypocholesterolemic effect, hypercholesterolemia was induced in mice with administration of 1.25% cholesterol and 0.5% cholic acid for 4 wk. After that 24 male Balb/c mice were randomly divided into four groups and fed basic, high-cholesterol, high-cholesterol with soy yogurt, or high-cholesterol with synbiotic soy yogurt diet for 5 wk. Blood samples were collected to measure lipids concentration and oxidative and antioxidative status. Proximate composition of SCLBP-formulated soy yogurt exhibits a marked difference from control soy yogurt in terms of total solids, moisture, protein, fat, ash, carbohydrate, and energy content. Results indicated that the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (75.28%) in synbiotic yogurt containing 2% SCLBP was significantly greater (P ≤ 0.05) compared with control soy yogurt (52.98%). In mice with hypercholesterolemia that were fed synbiotic soy yogurts, the yogurts had a favorable effect in reducing blood cholesterol, triglycerides, and low-density lipoprotein cholesterol and lipid peroxidation in liver. These led to a significant decrease of the atherogenic index compared with soy yogurt (control) only. Treatment with synbiotic soy yogurt cultures ameliorates lipid peroxidation in liver. These results indicated that the synbiotic soy yogurts have beneficial effects against hypercholesteroemia and can be used as a therapeutic agent in hypercholesteremic patients.

Effects of low-fat or full-fat fermented and non-fermented dairy foods on selected cardiovascular biomarkers in overweight adults

The association between consumption of full-fat dairy foods and CVD may depend partly on the nature of products and may not apply to low-fat dairy foods. Increased circulating levels of inflammatory biomarkers after consumption of dairy product-rich meals suggest an association with CVD. In the present study, we tested the effects of low-fat and full-fat dairy diets on biomarkers associated with inflammation, oxidative stress or atherogenesis and on plasma lipid classes. Within full-fat dairy diets, we also compared fermented v. non-fermented products. In a randomised cross-over study, twelve overweight/obese subjects consumed during two 3-week periods two full-fat dairy diets containing either yogurt plus cheese (fermented) or butter, cream and ice cream (non-fermented) or a low-fat milk plus yogurt diet, with the latter being consumed between and at the end of the full-fat dairy dietary periods. The concentrations of six inflammatory and two atherogenic biomarkers known to be raised in CVD were measured as well as those of plasma F2-isoprostanes and lipid classes. The concentrations of six of the eight biomarkers tended to be higher on consumption of the low-fat dairy diet than on that of the fermented dairy diet and the concentrations of two plasmalogen lipid classes reported to be associated with increased oxidisability were also higher on consumption of the low-fat dairy diet than on that of the fermented dairy diet (P< 0.001), although plasma F2-isoprostane concentrations did not differ on consumption of any of the diets. On the other hand, the concentrations of plasma sphingomyelin and IL-6 were significantly higher on consumption of the non-fermented dairy diet than on that of the low-fat dairy diet (P< 0.02). In conclusion, short-term diets containing low-fat dairy products did not lead to a more favourable biomarker profile associated with CVD risk compared with the full-fat dairy products, suggesting that full-fat fermented dairy products may be the more favourable.

General and persistent effects of high-intensity sweeteners on body weight gain and caloric compensation in rats.

In an earlier work (S. E. Swithers & T. L. Davidson, 2008), rats provided with a fixed amount of a yogurt diet mixed with saccharin gained more weight and showed impaired caloric compensation relative to rats given the same amount of yogurt mixed with glucose. The present 4 experiments examined the generality of these findings and demonstrated that increased body weight gain was also demonstrated when animals consumed a yogurt diet sweetened with an alternative high-intensity sweetener (acesulfame potassium; AceK) as well as in animals given a saccharin-sweetened base diet (refried beans) that was calorically similar but nutritionally distinct from low-fat yogurt. These studies also extended earlier findings by showing that body weight differences persist after saccharin-sweetened diets are discontinued and following a shift to a diet sweetened with glucose. In addition, rats first exposed to a diet sweetened with glucose still gain additional weight when subsequently exposed to a saccharin-sweetened diet. The results of these experiments add support to the hypothesis that exposure to weak or nonpredictive relationships between sweet tastes and caloric consequences may lead to positive energy balance.

Effect of a Western-Style Diet Fortified with Increased Calcium and Vitamin D on Mammary Gland of C57Bl/6 Mice

We previously reported hyperproliferation and hyperplasia in C57Bl/6 mouse mammary gland after feeding a Western-style diet (WD); these findings decreased after supplementing WD with increased calcium and vitamin D(3). We now again fortified WD with increased calcium and vitamin D(3) from two sources: (1) a food source, calcium- and vitamin D(3)-enriched yogurt (WD(y) diet) or (2) adding calcium and vitamin D(3) directly to WD (WD(CaD) diet). After 6 months of feeding the number of mammary ducts was higher in mice consuming WD compared to WD(y) (216.0 vs. 202.7, P <.05) and WD(CaD) (216.0 vs. 194.9, P <.001). The percentage of small ducts increased in WD compared to AIN-76A controls (23.3% vs. 17.4%) but was lower in the WD(y) (17.1%) and WD(CaD) (14.8%) groups. WD mice had higher numbers of epithelial cells per duct than WD(y) (33.2 vs. 27.4, P <.001) and WD(CaD) (33.2 vs. 27.8, P <.001) mice, and AIN-76A-fed mice had higher numbers than WD(y) (31.1 vs. 27.4, P <.005) or WD(CaD) (31.1 vs. 27.8, P <.01) mice. Mitotic index was higher in WD than in WD(CaD) mice (0.0020 vs. 0.0009, P <.001). Thus, small mammary gland ductules and mitosis increased after feeding WD and decreased after supplementing the diets with increased calcium and vitamin D(3), administered either in a dairy food (yogurt) or directly as calcium carbonate plus vitamin D(3) in WD, suggesting further study of these nutrients for their possible relationship to breast cancer prevention.

Dairy augmentation of weight and fat loss

In his letter, Kalman1 has raised some interesting points in response to our recent publication of yogurt augmenting total and central fat loss secondary to energy. However, the concern regarding compliance as a confounding variable appears to be unfounded. As indicated in the article, 'all subjects maintained complete diet diaries, and compliance was assessed by weekly subject interview and review of the diet diary and product return (analogous to pill counts)'. To expand upon this, subjects were judged to be compliant only if their diet diaries indicated they maintained a total calcium intake of 600 mg/day exclusive of the yogurt or gelatin desert, consumed 80–100% of the product provided (based on product return) and maintained an energy intake within 200 kcal of the daily energy prescription. Using these criteria, 13 of the 18 subjects on the yogurt diet and 10 of the 16 subjects on the control diet met all criteria for compliance. Separate analysis of the compliant subjects yielded comparable data to that found in the analysis of all subjects completing the trial, although the statistical significance achieved was stronger in the compliant group.

Dairy augmentation of total and central fat loss in obese subjects

We have previously demonstrated an antiobesity effect of dietary Ca; this is largely mediated by Ca suppression of calcitriol levels, resulting in reduced adipocyte intracellular Ca2+ and, consequently, a coordinated increase in lipid utilization and decrease in lipogenesis. Notably, dairy Ca is markedly more effective than other Ca sources. Obese subjects were placed on balanced deficit (-500 kcal/day) diets and randomized to control (400-500 mg Ca/day; n = 16) or yogurt (1100 mg Ca/day; n = 18) treatments for 12 weeks. Dietary macronutrients and fiber were held constant at the US average. Body weight, body fat and fat distribution (by dual-energy X-ray absorptiometry), blood pressure and circulating lipids were measured at baseline and after 12 weeks of intervention. Fat loss was markedly increased on the yogurt diet (-4.43+/-0.47 vs -2.75+/-0.73 kg in yogurt and control groups; P<0.005) while lean tissue loss was reduced by 31% on the yogurt diet. Trunk fat loss was augmented by 81% on the yogurt vs control diet (P<0.001), and this was reflected in a markedly greater reduction in waist circumference (-3.99+/-0.48 vs -0.58+/-1.04 cm, P<0.001). Further, the fraction of fat lost from the trunk was higher on the yogurt diet vs control (P<0.005). Isocaloric substitution of yogurt for other foods significantly augments fat loss and reduces central adiposity during energy restriction..

Trophic status of the small intestine in young and aged rats: modulation by a yogurt-supplemented diet.

Among the multifactorial causes of undernutrition in old age, gastrointestinal mucosa altered function and resulting specific malabsorption are the most relevant. Despite numerous studies that have dealt with the effects of aging on the digestive tract of mammals, results showed discrepancies in terms of proliferation and biochemical aging small intestine events. However, the slowing-down of the maturation process and the poor adaptation of metabolism and intestinal function are obvious and there is evidence that protective mechanisms are impaired with age and contribute to affecting the trophic activity and related systemic homeostasis. Good prospects to improve gastrointestinal function in the elderly are essential and research on nutritional intervention to limit and counteract age-related impairments must be extensive. Probiotics are good candidates and fermented milks might be of great interest. In the present study we first show the main structural and functional variations between 3- and 23-month-old rat small intestines. The trophic consequences of aging and nutritional adaptation under basal conditions are also analyzed and discussed after 20 days of a yogurt-supplemented specific diet in both young and aged rats. The main variations that occur with aging and yogurt diet are located in the proximal small intestine. The present findings indicate a slight improvement of morphological trophic parameters in both young and aged rats by yogurt, whereas enzymatic changes are more discrete. Despite the obvious age-related decrease in trophicity, we suggest that assessment of probiotic potentials on trophicity requires a more altered model than normal, healthy aging animals.

Feed efficiency and splenic lymphocyte proliferation response in yogurt- and milk-fed mice

Weight gain, feed efficiency and proliferation response of splenic lymphocytes were studied in mice fed either a yogurt or a milk-based diet. The yogurt contained live Lactobacillus bulgaricus and Streptococcus thermophilus. The feeding trial lasted for 10 months. Proliferation response of lymphocytes was measured by the uptake of tritiated thymidine into the cells when stimulated with the mitogens phytohaemagglutinin (PHA), concanavalin A (Con A) and Escherichia coli lipopolysaccharide (LPS). There was no significant difference between the average body weight of mice belonging to the two dietary groups. But yogurt diet showed a higher feed efficiency ratio when compared to the milk diet for the first 8 weeks of the study while the mice were growing. After the period of growth was over, yogurt-fed mice maintained a constant body weight like the milk-fed mice but on a lower energy intake. The proliferation of splenic lymphocytes, expressed as Stimulation Index, was significantly higher in response to the T-lymphocyte mitogens Con A and PHA. Results suggest that yogurt has better feed efficiency and its long term inclusion in diets primes the splenic T-lymphocytes for a higher mitogenic response.

Dietary Management of Persistent Diarrhea: Comparison of a Traditional Rice-Lentil Based Diet with Soy Formula

Recent studies have indicated that enteral diets can play an important role in the treatment of persistent diarrhea. Khitchri, a local weaning food in Pakistan, is composed of rice and lentils, which have previously been shown to be well tolerated in many children with acute diarrhea. The effectiveness of a khitchri and yogurt (KY) diet, which is inexpensive and widely available in Pakistan, was studied. One hundred two weaned boys (6 to 36 months old) with persistent diarrhea were randomly assigned to receive either soy formula (group A) or the KY diet (group B) for 14 days. Group A also received the KY diet in addition to formula for days 8 through 14. Twenty-nine children did not complete the study because of severe infection (13) or their family's decision to leave the study early (9 in group A and 7 in group B). Sixty-six children successfully completed the study protocol; there were five clinical failures in group A and two in group B. On a comparable caloric intake, there was a significantly lower stool volume (group B: 38 +/- 16 [mean +/- SD] vs group A: 64 +/- 75 g/kg per day, P less than .05) and frequency (B: 4.4 +/- 2.0 vs. A: 6.6 +/- 4.2 stools per day, P less than .005) in children fed KY during the first week of therapy. Group B children also had a significantly greater weight gain than children in group A during the first week (B: 468 +/- 373 g/wk vs A: 68 +/- 286 g/wk, P less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Lactose Malabsorption in Children with Symptomatic Giardia lamblia Infection

An investigation was carried out on 61 children suffering from symptomatic giardiasis with the object of verifying the incidence and entity of lactose malabsorption. Furthermore, the possibility of a substitutive yogurt diet was verified in the lactose malabsorbers. The subjects, all children older than 1 year, were studied according to a schedule that included a lactose hydrogen breath test (BT) performed prior to therapy and a further BT 60 days following therapy. The subjects were divided in two groups: group A, 40 children, received a dose of 250 ml of cow's milk; group B, 21 children, received a stress dose of 2 g/kg lactose (max 50 g). Those subjects who were lactose malabsorbers at the 60 day follow‐up were also given a BT at 75 days, and in the case of persistent malabsorption, a further BT was performed after 24 h with the administration of yogurt (450 g containing 12.1 g of lactose). Furthermore, 40 subjects matched for age and sex but without any GI complaints served as controls. The results showed lactose malabsorption to be frequent in children with Giardia lamblia symptomatic infection. According to the BT with a standard lactose load, all patients were malabsorbers; when testing lactose absorption with 250 ml of cow's milk, 45% of patients were found to be malabsorbers. In the latter subjects, the oral load of yogurt was uniformly well tolerated and gave rise to no H2 increment on the BT. We conclude that the occurrence of lactose malabsorption of nutritional relevance is common in children suffering or having suffered from giardiasis. Such children, however, may benefit from the administration of yogurt, whose lactose appears to be well absorbed.

Lactose malabsorption in children with symptomatic Giardia lamblia infection: feasibility of yogurt supplementation.

An investigation was carried out on 61 children suffering from symptomatic giardiasis with the object of verifying the incidence and entity of lactose malabsorption. Furthermore, the possibility of a substitutive yogurt diet was verified in the lactose malabsorbers. The subjects, all children older than 1 year, were studied according to a schedule that included a lactose hydrogen breath test (BT) performed prior to therapy and a further BT 60 days following therapy. The subjects were divided in two groups: group A, 40 children, received a dose of 250 ml of cow's milk; group B, 21 children, received a stress dose of 2 g/kg lactose (max 50 g). Those subjects who were lactose malabsorbers at the 60 day follow-up were also given a BT at 75 days, and in the case of persistent malabsorption, a further BT was performed after 24 h with the administration of yogurt (450 g containing 12.1 g of lactose). Furthermore, 40 subjects matched for age and sex but without any GI complaints served as controls. The results showed lactose malabsorption to be frequent in children with Giardia lamblia symptomatic infection. According to the BT with a standard lactose load, all patients were malabsorbers; when testing lactose absorption with 250 ml of cow's milk, 45% of patients were found to be malabsorbers. In the latter subjects, the oral load of yogurt was uniformly well tolerated and gave rise to no H2 increment on the BT. We conclude that the occurrence of lactose malabsorption of nutritional relevance is common in children suffering or having suffered from giardiasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors Affecting the Protein Quality of Yogurt and Acidophilus Milk

The apparent protein digestibility in vivo, the protein digestibility in vitro, the net protein ratio, and computed protein efficiency ratio were used to assess the protein quality of yogurt and acidophilus milk as affected by heat treatment, direct acidification, addition of culture, or fermentation. Rats fed diets containing either heated mix or yogurt tended to eat more and gain more weight than rats fed diets containing either unheated mix or the acidified yogurt. Feed efficiency was also significantly higher for rats fed heated mix and yogurt. The apparent protein digestibility in vivo was significantly higher in yogurt diet than in the unheated yogurt mix diet. The net protein ratio of the yogurt diet was significantly higher than that of either the unheated mix or the acidified yogurt but not significantly different from the heated mix. The computed protein efficiency ratio values were also increased with both heating and fermentation. The direct acidified yogurt had a significantly lower net protein ratio and lower computed protein efficiency ratio than the fermented yogurt. Rats fed either sweet acidophilus (unfermented) or acidophilus milk exhibited a significantly higher protein digestibility than rats fed heated milk, indicating that the lactic culture may have a direct effect on protein digestibility. Despite their increased protein digestibilities, the acidophilus products did not display any significant increase in net protein ratio or computed protein efficiency ratio.

Amelioration of the adverse effect of a gastrointestinal challenge with Salmonella enteritidis on weanling rats by a yogurt diet

The response of yogurt-fed rats and the corresponding unfermented milk-fed rats to an infectious gastrointestinal challenge has been compared. After 1 (2 trials), 7 (4 trials), 14 and 21 (1 trial each) days on freeze-dried milk or yogurt diets, the rats were inoculated intra-gastrically by intubation per os with 4.5 X 10(10) +/- 0.7 colony forming units (mean +/- SEM) of Salmonella enteritidis. Challenged and control rats were monitored during the 3 weeks post-inoculation for viability, weight gain, feed consumption, and feed efficiency. In general, challenged yogurt-fed rats exhibited significantly superior weight gain and feed efficiency (but not feed consumption) values in week 1 post-infection, but the differences were not significant in week 2 post-infection. Sick milk- and yogurt-fed rats convalesced in week 3. Pooled mortality data indicated that yogurt-fed rats survived better than milk-fed rats. Yogurt did not prevent salmonellosis per se but significantly reduced the mortality and weight gain deceleration.

Galactose-metabolizing enzymes in the rat.

The induction of galactose-type cataracts in rats with a yogurt diet (1) resembles the natural cataractogenic action of the milk sugars in patients with galactosemia, a hereditary disease characterized by galactose-1-phosphate uridyl transferase deficiency. The role of the transferase and other galactose-metabolizing enzymes in the pathogenesis of cataracts in rats has not been assessed, however, although enzymes in the glycolytic (2-4) and oxidative shunt pathways (5, 6) are inhibited when rats are fed strict galactose diets. Indeed, the decreasing activities of the liver enzymes, galactokinase (7), transferase (8, 9), and uridine diphosphogalactose-4-epimerase (10) in the aging rat suggest that one or all of the enzymes of the sugar nucleotide pathway limit carbohydrate metabolism in rats fed on galactose. There appears to be a similar age-dependence in the respective red cell enzymes.Materials and Methods. Male Wistar rats were bled from the heart at 1, 2, 3, 8, and 16 weeks of age in groups of three o...

Cataracts Produced in Rats by Yogurt

Rats kept on an exclusive diet of yogurt avidly ate the yogurt, grew at a normal rate, were normally active, mated, conceived, and gave birth to normal, healthy litters. However, all of the rats developed cataracts. Cataracts appeared in young rats 2 to 3 months, and in adult rats 4 to 6 months, after initiation of the yogurt diet. Cataracts first manifested themselves in small vacuoles at the periphery of the lens and then in small striae extending toward the center of the lens. These striae progressively became longer, more coarse, and numerous until they coalesced, finally forming a mature white lens. The high content of galactose in commercially available yogurt could account in full for appearance of cataracts in 100 percent of the experimental animals. The cataracts appear to be the same as those produced by diets with a high content of galactose.