Fermented Milk and History|Beneficial & Therupatic effects of Fermented Products

Fermented milk in Health

1.Alleviation of Lactose Malabsorption by drinking Fermented Milks

• Lactose malabsorbers often complain of “gastric distress” after consuming fresh, unfermented milk or milk products. Lactose malabsorption is a condition in which lactose, the principal carbohydrate of milk, is not completely hydrolysed into its component monosaccharides, glucose, and galactose. Since lactose is broken into its constituent monosaccharides with the help of lactase or Beta D-galactosidase enzyme, lactose malabsorption results from a deficiency of this enzyme.
• Lactase deficiency is a common problem in many parts of the world. The prevalence of lactose malabsorption varies depending on the ethnic origin of the population. Infants in general have higher lactase activity than adults. Prevalence of lactose malabsorption is common in China, Thailand, Japan, and Africa and Australian aborigines, but less common among Caucasians. Temporary deficiency of beta-galactosidase occurs in people suffering from diarrhoea’s unabsorbed lactose reaches the colon, where it is fermented by colonic flora to volatile fatty acids, lactic acid, CO2, H2, and CH4. The unhydrolyzed lactose withdraws water and electrolytes from duodenum and jejunum. The lactase deficient people can suffer from bloat, flatulence, abdominal pain, and diarrhoea.
• Fermented milk, in particular, yoghurt appears to be well tolerated by lactose malabsorbers and lactose malabsorbers suffer fewer symptoms with fermented dairy foods. Reduced levels of lactose in fermented products are due to partial hydrolysis of lactose during fermentation and is partly responsible for greater tolerance of yoghurt. Factors other than the presence of yoghurt starter are responsible for better tolerance of lactose in lactose maldigests from fermented dairy foods.
• At least three factors appear to be responsible for better tolerance of lactose from yoghurt including (a) yoghurt bacteria, (b) lactase enzyme or beta-galactosidase elaborated by these bacteria.
• The traditional cultures used in making yoghurt (i.e., Lb. delbrueckii ssp. bulgaricus and Str. thermophilus)  contain substantial quantities of Beta-D-galactosidase, and it has been suggested that the consumption of yoghurt containing cultures with high levels of lactase may assist in alleviating the symptoms of lactose malabsorption.
• Slower gastric emptying of semisolid fermented milk products such as yoghurt is another factor responsible for better absorption of lactose. Delayed gastric emptying is responsible for the hydrolysis of lactose by indigenous beta-d galactosidase located in the sides and tips of the villi of the jejunum and by bacterial beta d galactosidase. Viscous foods such as yoghurt or foods with higher solids are reported to delay gastric emptying and are effective in alleviating lactose intolerant symptoms.

2.Antimicrobial Activity and Gastrointestinal Infections by use of Fermented Milk

• The gastrointestinal tract has a large number of indigenous microflora. There is a balance between useful microorganisms and harmful microflora. This balance is affected by gastrointestinal illnesses, stress, and use of antibiotics leading to disturbances of its function.
• Fermented milk has been used to improve intestinal health since ancient times. This includes diarrhoea caused by infection due to pathogenic bacteria. Fermented foods are reported to improve the composition and metabolic activity of intestinal microflora.
• Fermented milk has shown beneficial effects on intestinal health. Reduction of infant diarrhoea and antibiotic-associated diarrhoea due to consumption of fermented milk has been reported.
• Consumption of fermented milk has shown to increase the counts of bifidobacteria and decrease the levels of putrefactive compounds in faeces. This is because of the enhancement of intestinal immune function by lactic acid bacteria in fermented milk and antimicrobial substances produced during fermentation, which have shown improvement in intestinal microflora.

3.ANTICANCER EFFECT OF FERMENTED MILK

Yoghurt has been found to reduce the levels of bacterial enzymes, glucuronidase, azoreductase, and nitroreductase. These enzymes are believed to contribute to the pathogenicity of bowel cancer as they catalyse the conversion of procarcinogens to carcinogens (Lankaputhra and Shah, 1998; Goldin and Gorbach,1977, 1984, Cenci et al., 2002).

• Cancer is one of the main causes of death in the world. Epidemiological studies suggest that cancer is caused by environmental factors, particularly diet.
• Several factors are responsible for causes of colorectal cancer including bacteria and metabolic products such as genotoxic compounds (nitrosamine, heterocyclic amines, phenolic compounds, and ammonia). Many bacterial enzymes such as beta-glucuronidase generate these carcinogenic products, except lactic acid bacteria and probiotics, such as Lactobacilli and bifidobacteria.
• Lactic acid bacteria and fermented products have potential anticarcinogenic activity. An inverse relationship between the consumption of fermented dairy foods and the risk of colorectal cancer has been found. Lactic acid bacteria suppress bacterial enzymes and reduce intestinal pH.
• Several studies have shown that fermented dairy products or preparation containing lactic acid bacteria inhibit the growth of tumour cells in experimental animals. Animal studies using chemical carcinogen 1, 2-dimethyl hydrazine (DMH) have been carried out. Rats were given DMH to induce colon cancer and fed with fermented milk. DMH is activated in the large intestine by beta-glucuronidase. Addition of Lactobacillus to the diet has been reported to delay tumour formation. The inhibitory effects of fermented milk on colon cancer are either because of the decrease of mutagenic activity or modification of intestinal microflora.
• Several types of fermented milk including yoghurt, colostrum fermented with Lb. delbrueckii ssp.bulgaricus, Str. thermophilus, and Lb. acidophilus or milk fermented with Lb. helveticus are reported to suppress cancer cell growth.

4.Reduction in Serum Cholesterol

Elevated levels of serum cholesterol, particularly LDL-cholesterol have been linked to an increased risk of cardiovascular disease, which is one of the main causes of death. Cholesterol-lowering properties of fermented milk were observed as early as the 1960s among Masai tribes of East Africa. Mann and Spoerry (1974) observed a decrease in serum cholesterol levels in men fed large quantities (8.33 L/man/day) of milk fermented with Lactobacillus. Those people had low-blood cholesterol levels although they consumed a large quantity of meat.

• Consumption of a high quantity of yoghurt was found to be responsible for lowering of serum cholesterol. Rabbits fed on a high cholesterol diet supplemented with yoghurt showed lower cholesterol levels as compared to the diet supplemented with nonfermented milk.
• Cholesterol-lowering effects of yoghurt have been reported in human volunteers. The subjects consumed 240 mL of yoghurt three times per day. The role of fermented milk in reducing serum cholesterol is not completely understood.
• Cholesterol is an essential component of cell membrane and is required to produce certain hormones and bile acids. It is synthesized by the liver and from absorbed foods.
• The mechanism of controlling blood cholesterol level is complex. The metabolite of starter cultures in fermented milk is reported to produce hydroxymethyl-glutarate, which inhibits hydroxymethylglutaryl-CoA reductase, an enzyme required for the synthesis of cholesterol in the body. This could limit cholesterol synthesis.

5.Immune System Stimulation by use of fermented Milk

• The health benefits of fermented milks are primarily because of the ability of starter bacteria to survive in the gastrointestinal tract. Yogurt starter bacteria are reported to survive in the stomach and are also found in feces.
• The intestinal system defends the body against bacterial and viral infection and cancer and allergies. The intestine is the body’s largest immune organ and the intestinal microflora and the metabolic activity of intestine is equivalent to that of the liver.
• The intestinal tract works as a peripheral organ to protect against intestinal infections and affects systemic immunological function. Its function is affected by intestinal microflora.
• The mechanism for immunomodulation is not clearly understood. Lactic acid bacteria (LAB) are likely to, directly or indirectly (by changing the composition or activity of the intestinal microflora), influence the body’s immune function, but the mechanism is not fully understood.
• Fermented milk has been reported to inhibit infections in mice caused by Klebsiella pneumonia. Mice fed with fermented milk were healthier and lived longer. In a human clinical study, feeding yoghurt starter bacteria in yoghurt increased the serum level of gamma-interferon and NK cell count.
• Yoghurt bacteria are reported to have nitrate reductase activity. Nitrate is an intermediate product in the formation of N-nitroso compounds, which are highly carcinogenic.