Yogurt is made by inoculating certain bacteria (starter culture), usually Streptococcus thermophilus and Lactobacillus bulgaricus, into milk. After inoculation, the milk is incubated at approximately 110°F ± 5°F until firm; the milk is coagulated by bacteria-produced lactic acid.
You must use a brand of plain yogurt whose label indicates that the product contains a live culture; some brands of plain yogurt do not contain a live culture because the yogurt has been pasteurized. -
Making Yogurt at HomeYogurt is made by curdling milk with purified cultures of two special bacteria--Lactobacillus bulgaricus and Streptococcus thermophilus--that cause the milk sugar (lactose) to turn into lactic acid. The pasteurized (and usually homogenized) milk is inoculated with the cultures, then warmed in an incubator for several hours; during this time the yogurt thickens and develops its distinctive flavor. Nonfat milk solids are often added to thicken the yogurt; this also adds protein.
In some types of yogurt, the bacteria survive the processing; in other cases, the milk is pasteurized again after the cultures are added, and the bacteria are destroyed. This is more often the case in Swiss-style brands. Many frozen yogurt products are pasteurized after culturing, too. Check the ingredient listing for "active yogurt cultures" or "living yogurt cultures." Yogurt that has been pasteurized subsequent to culturing will be labeled "heat-treated after culturing."
Because yogurt is cultured, it is more digestible than milk for some people with lactose intolerance: The live cultures create lactase, the enzyme in which lactose-intolerant people are deficient. However, the amount of lactose remaining varies from 25% to 80%. Active cultures also aid in the digestion of casein, a milk protein. And there is evidence that live yogurt cultures may help to restore the "friendly" bacteria in the intestines, after the bacterial balance of the digestive system has been upset by the use of antibiotics. -
WholeHealthMDYogurt may also be easier to digest than regular milk by those who cannot digest lactose, a sugar in milk products. Many people in the world, including some 40 million Americans, are lactose intolerant. The condition is very common except among people of European ancestry. For the lactose
intolerant, dairy products containing significant amounts of lactose cause diarrhea, abdominal cramps, and nausea.
Yogurt is easier to digest because enzymes from the yogurt bacteria break down some of the lactose during the fermentation process. There's also preliminary evidence that once the yogurt's eaten, the bacteria may continue to help break down lactose in the intestinal tract.
Some researchers say yogurt can help manage diarrhea caused by antibiotic therapy by reestablishing the "good" bacteria killed along with the bad during treatment.
"I think the jury's still out on this," says Sutnick. "I am seeing enough research that I would no longer 'pooh-pooh' these things as silly. But I think we need more research before we can be sure.
"If you have diarrhea from antibiotics," she says, "try eating some yogurt. It's certainly nutritious, it can't hurt you, and it might even help."
It's common folklore among women that yogurt cultures can help ward off vaginal yeast infections by countering harmful bacteria.
Doctors don't agree on whether this is so, however. Some cautiously recommend yogurt to their patients; others say it's useless.
"I can't say it definitely worked, but the preliminary data suggest yogurt may be helpful [in preventing yeast infections]," says Eileen Hilton, M.D., an assistant professor at the Albert Einstein College of Medicine in the Bronx, N.Y.
Hilton authored a small study published in the March 1 issue of the Annals of Internal Medicine that showed eating yogurt containing Lactobacillus acidophilus reduced the incidence of vaginal infections. She plans to follow it up with a larger study using more patients and a variety of flavors and types of yogurt.
Until more proof is available, however, many doctors remain skeptical.
"Eating the yogurt doesn't do a whole heck of a lot" to treat yeast infections, says Michael Spence, M.D., the American College of Obstetricians and Gynecologists' expert on vaginitis and professor of obstetrics and gynecology at the Hahnemann University School of Medicine in Philadelphia.
Spence says even douching with plain yogurt, which puts the yogurt cultures in direct contact with the vagina, doesn't help.
"It's not going to do any harm, it's just going to prolong the agony," Spence says. "I've tried a lot of different [remedies] with my patients, including yogurt. It just doesn't work."
Other scientists have explored whether yogurt can reduce blood cholesterol levels. Several studies conducted on Maasai warriors in East Africa found that when they ate large quantities of yogurt, their cholesterol levels went down even though they gained weight.
The American Heart Association, however, discounts these results.
"I would not agree with those studies," says Margo Denke, M.D., who does research on nutrition and cardiovascular disease and serves on the AHA nutrition committee.
"The key to lowering cholesterol is to reduce saturated fat in the diet," she says. "There's some evidence that calcium can reduce saturated fat absorption, but it's only a small amount, a couple of grams."
Researchers have also explored yogurt's effects on cancer in rats. A few studies conducted in the early 1980s reported that yogurt decreased colon cancer tumors in rats, but those effects have not been duplicated in humans.
"There have been some interesting leads, but nothing has crystallized out of it," says Anthony Hitchins, an FDA microbiologist who formerly conducted and reviewed yogurt research at USDA's Human Nutrition Research Center.
Enthusiasm and research about yogurt's anti-tumor effects have fizzled, Hitchins says. "If something really exciting had come out of it, we would have heard about it."
Freshly made yogurt with live cultures contains about 1 billion bacteria per gram, according to All About Yogurt, by William Helferich and Dennis Westhoff (Prentice-Hall, Inc., 1980). As it sits on the shelf, however, the yogurt's S. thermophilus eventually die off from the acidic environment. Refrigerated yogurt, even one to two weeks after fermentation, will probably
still have about 1 million bacteria per gram. -
FDA.gov There's a medical truism that states: "You're only as healthy as your colon." When eating yogurt, you care for your colon in two ways. First, yogurt contains lactobacteria, intestines-friendly bacterial cultures that foster a healthy colon, and even lower the risk of colon cancer. Lactobacteria, especially acidophilus, promotes the growth of healthy bacteria in the colon and reduces the conversion of bile into carcinogenic bile acids. The more of these intestines-friendly bacteria that are present in your colon, the lower the chance of colon diseases. Basically, the friendly bacteria in yogurt seems to deactivate harmful substances (such as nitrates and nitrites before they are converted to nitrosamines) before they can become carcinogenic.
Yogurt improves the bioavailability of other nutrients. Culturing of yogurt increases the absorption of calcium and B-vitamins. The lactic acid in the yogurt aids in the digestion of the milk calcium, making it easier to absorb.
Yogurt can boost immunity. Researchers who studied 68 people who ate two cups of live-culture yogurt daily for three months found that these persons produced higher levels of immunity boosting interferon. The bacterial cultures in yogurt have also been shown to stimulate infection-fighting white cells in the bloodstream. Some studies have shown yogurt cultures to contain a factor that has anti-tumor effects in experimental animals.
A 1999 study reported in Pediatrics showed that lactobacillus organisms can reduce antibiotic-associated diarrhea.
There are a few studies that have shown that yogurt can reduce the blood cholesterol. This may be because the live cultures in yogurt can assimilate the cholesterol or because yogurt binds bile acids, (which has also been shown to lower cholesterol), or both.
BEST YOGURT
Contains only live and active cultures (LAC seal) and milk
OKAY YOGURT
Contains live and active cultures (LAC seal), milk, and some filler ingredients.
DON'T-EVEN-BUY YOGURT
It might as well be pudding. It says "heat treated" on the label, and it may contain added sugar and stabilizers - and more!
AskDrSears.comLive, Active, And Probiotic: The Yogurt Culture
by Pat Kendall, Ph.D., R.D.
Food Science and Human Nutrition Specialist
Colorado State University
Cooperative Extension
Yogurt deserves its reputation as a healthful food. It's a
great source of protein and calcium. When made with non- or
low-fat milk, it's low in fat. If it contains live starter
cultures, it can aid digestion.
Some manufacturers add other cultures during processing to
enhance the health-promoting potential of yogurt. The most
commonly added cultures include Lactobacillus acidophilus, L.
casei, L. reuteri and Bifidobacterium bifidum. These "probiotic"
bacteria pass through the stomach to the gastrointestinal (GI)
tract. There, they help maintain a healthy balance between the
200-plus kinds of bacteria that live there. -
College of Agricultural Sciences, Penn State University-----------------------
Yes, some yogurt cultures contain bacteria, and I wouldn't buy any that doesn't.
Since our systems contain bacteria, adding
certain bacteria does seem to make sense.
I think that the most common use that our internal bacteria has is in aiding digestion. Note the last sentence of the last entry above.
Count me as one who believes that yogurt is more than just a healthy choice becaue of its calcium and vitamins. I don't see it as a cure-all, but do think it helps in several ways. My grandfather used to make his own yogurt, as did my father, as do I. My son has already asked me how to do it. We use it both as as ingredient
in cooking some recipes and
on some things, often as a replacement for sour cream or cream cheese. Even if none of the claimed health benefits above are true, yogurt is still better for you than sour cream.
