LONDON, Ont. -- You almost need a degree in nutrition to buy yogurt these days.

More than just brand and flavour, choices include high-fat, low-fat and fat-free; no-sugar added, sugar-free or naturally sweetened with honey or stevia; probiotic or prebiotic; lactose-free; enriched or organic, not to mention drinkable yogurt, tube yogurt, frozen yogurt or kefir.

The neolithic people of central Asia who probably created yogurt accidentally around 6000 BC would be dumbfounded.

In North America, yogurt didn't really catch on until the 1950s and '60s with an increasing interest in health food, but in recent years, the available varieties have grown exponentially as manufacturers try to appeal to every dietary niche and taste.

Any of these many choices is good if it helps you reach Canada's Food Guide's recommendation of two to four servings of milk and alternatives per day (depending on age and gender), says Nathalie Savoie, a registered dietitian and assistant director for nutrition for Dairy Farmers of Canada, based in Montreal.

"I don't think there is a 'best' choice. I think that whatever suits your taste and your need and is a great way to help you reach the amount that you need every day is what I would qualify the 'best' choice."

One minor problem, she says, is that "single-serving" yogurt is usually packaged in 100-gram containers. But Health Canada's definition of one serving is 175 grams (3/4 cup), so one container of yogurt is only slightly more than half of one recommended serving.

One of the primary reasons yogurt is considered a health food is that it contains lactobacteria, "good" bacteria that promotes gastro-intestinal health. It is also a rich source of calcium and a good source of protein. Because of the culturing process, it is also easier to digest than milk and can even be eaten by many people who cannot tolerate milk, according to the Dairy Farmers of Canada website (www.dairyfarmers.ca).

One growing trend is make-your-own yogurt. The only ingredients are milk, yogurt cultures (available at many supermarkets) and flavouring of choice.

"It's easy," says Savoie, who makes her own yogurt all the time. She has a yogurt machine, but the Internet is full of suggestions for ways to make it without special equipment.

When the cultures or bacteria are added to warmed milk, they convert the lactose (milk sugar) to lactic acid, which thickens the milk and gives it that tang. When the yogurt is cooled, it can then be flavoured precisely to taste with known ingredients. Stabilizers such as gelatin also may be added.

The only trick is that the milk and cultures have to be maintained at a certain temperature for several hours and the container cannot be moved or jiggled while processing.

"The advantage of making your own yogurt is that you can use milk that's fortified with vitamin D," Savoie says. "Some manufacturers use fortified milk to make yogurt," she explains, but those that don't are prohibited from adding it as a supplement.

There are three basic kinds of yogurt sold. With Balkan- or set-style, the warm cultured milk mixture is poured into containers and incubated without further stirring. It is fairly thick and can be eaten plain or used in recipes.

With Swiss-style or stirred yogurt, the cultured milk is incubated in a large vat, cooled and then stirred for a creamy texture, often with fruit or other flavourings added. It is often slightly thinner than Balkan-style and can be eaten as is, in cold beverages or incorporated into desserts.

Greek or Mediterranean yogurt is very thick and is either made from milk that has had some of the water removed or by straining whey from plain yogurt to make it thicker and creamier.

It tends to hold up better when heated than regular yogurt and is usually Caroline McCann's first choice when cooking with yogurt.

McCann of Magog, Que., in the Eastern Townships, is the owner of Chefadom, an in-home catering service, host of two cooking shows on Quebec television -- "1 ingredient 3 facons" ("1 Ingredient 3 Ways") and "Chef a la rescousse" ("Chef to the Rescue") and also works with Dairy Farmers of Canada.

While yogurt adds a tang or freshness to dishes that other dairy products do not, what she really likes is the texture.

"I like to use it at the end of cooking to bring that velvety texture to a sauce or chicken dish or any kind of dish. With the Greek-style yogurt, if you add this at the end of a dish, you get the same consistency as if you would use either creme fraiche or 35 per cent cream."

It can also be used as a substitute for sour cream or, when combined two to one with milk, as a substitute for buttermilk.

Because she's looking for that creamy texture, she usually uses yogurt with a higher fat content. "You can always choose the healthier versions, but the result won't be quite the same."

Among her favourite dishes using yogurt are classic poulet au buerre (butter chicken) and dipping sauces such as Greek tzatziki and Indian raita.