Yogurt is one of the oldest fermented dairy foods in the world. Its origins date back to the dawn of civilisation.
When humans began domesticating animals for milk production, milk’s short shelf life required solutions for storing it.
The word ‘yogurt’ itself comes from Turkish, meaning something like ‘curdled’ or ‘thickened milk’, which is pretty much what happens to milk during yogurt production.
Like milk, yogurt is a rich source of calcium and protein. And it provides other nutrients such as iodine, vitamins D, B2 and B12, and zinc.
But yogurt is actually more nutritious than milk. The main reason is that the fermentation process makes it easier to digest, so the nutrients can be absorbed more easily into the body.
Yet with all the various types, like Greek and liquid yogurts, and ones with added fruits and probiotics, how do you know which one is healthiest?
The yogurt industry is booming – so picking the right one can be complicated
Yogurt is made by introducing certain bacteria into fresh milk – typically Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus.
Usually, both these bacteria are present in yogurt and form the yogurt starter culture.
Their synergistic relationship is a key factor in the consistency of the final product.
These cultures may also provide some health benefits, such as reducing the severity and duration of diarrhea.
The bacteria ferment the naturally occurring milk sugar (lactose) for energy and growth.
During this process, lactose becomes lactic acid.
The acidity development leads to the main milk protein, casein, breaking down and losing some of its elementary structure.
This partial breakdown results in the semi-solid, gel-like structure we know as yogurt.
The lactic acid is also responsible for yogurt’s sour flavors, as well as helping it stay fresher for longer than milk.
Yogurt is made by introducing certain bacteria into fresh milk – typically Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus
Why is yogurt healthy?
Yogurt is easier to digest than milk because enzymes involved in the fermentation process break down substances, such as lactose, into smaller compounds, which can be readily absorbed and used by the body.
And certain minerals, such as calcium, phosphorus and iron, are better used by the body when they come from yogurt.
And because lactose is broken down and converted to lactic acid during fermentation, lactose-intolerant people can consume yogurt without adverse effects.
Consuming yogurt is associated with many health benefits, including maintaining a healthy microbiota (the colony of bacteria in your gut).
Yogurt can feed the good bacteria and help them fight against disease-causing microorganisms.
Yogurt consumption helps to maintain bone structure and has even been found to reduce the risk of certain cancers and infectious diseases, as it enhances the immune response.
Yogurt can help reduce symptoms of conditions such as constipation, inflammatory bowel disease, infection with a bacterium that can damage the stomach lining (Helicobacter pylori), diarrheal diseases and some allergic reactions, such as to certain foods.
Types of yogurt
Cow’s milk is the most widely used raw ingredient for yogurt manufacturing. But other types, such as sheep and goat milk yogurt, are available.
There are slight differences in the nutritional composition among these milk types.
Although cow’s milk is generally more appealing (as goat and sheep milk may have unpleasant smells), the latter two may provide additional health benefits.
For instance, goat’s milk is easier to digest than cow’s milk and is less likely to cause an allergic reaction.
Non-dairy alternatives such as soy and coconut milk yogurt are becoming increasingly popular too.
The most commonly known types of yogurt are plain set yogurt, flavored yogurt, Greek yogurt, frozen yogurt and drinking yogurt.
Plain set yogurt is usually made from dairy ingredients and fermented in the cups or tubs with no sugar or sweeteners.
Kefir is a popular type of drinking yogurt, often lactose free as the bacteria break it down
Lassi (left) is a popular drinking yogurt type from India; Greek yogurt is thick and creamy
Flavored yogurt is made by adding sugar and fruit or other flavorings to plain yogurt.
Often, the milk mixture is fermented in large vats, cooled and then stirred for a creamy texture with various fruits or other flavors. These stirred yogurts are also known as Swiss-style yogurts.
Greek yogurt is a thick yogurt. It’s traditionally prepared by straining the water known as whey from plain yogurt to make it thicker, richer and creamier. It contains more protein than regular yogurt and has no added sugar.
Frozen yogurt is frozen ice milk with a typical yogurt flavor. It tastes more like ice-cream with a hint of yogurt.
Drinking yogurts are prepared from a yogurt mix with reduced milk solids. They come in almost every variety and flavor.
They’re usually more watery, but some thick varieties are also available. Kefir and lassi are the popular drinking yogurt types.
Added ingredients for health purposes
Many yogurts contain added ingredients. These include cholesterol-lowering compounds(such as stanol and sterol esters) and fiber aimed at improving gut health.
Some yogurts also have added probiotics. These are live microorganisms that can help establish a healthy gut microbiota. The most widely used probiotics are the acidophilus strain, known as Lactobacillus acidophilus, and Bifidobacterium. These could be useful for people who have gastrointestinal problems such as irritable bowel syndrome (IBS).
Probiotics can be more effective when consumed in yogurt than through capsules or other beverages.
The two bacteria in yogurt starter culture – S. thermophilus and L. delbrueckii ssp. bulgaricus– are not natural inhabitants of the intestine and cannot survive the acidic conditions and bile concentrations in the gastrointestinal tract. So they don’t do much to change the microbiota in your gut. In contrast, probiotics can survive and colonize the large intestine.
Regular intake of yogurt that contains microbial cultures such as probiotic acidophilus has also been found to potentially reduce the risk of coronary heart disease by helping to decrease cholesterol absorption.
When whole milk is used to produce plain yogurts, these may contain 3.5-4.4 grams of fat per 100g. Low-fat yogurt contains less than 3g of fat per 100g, and non-fat or fat-free yogurts must contain less than 0.15g fat per 100g.
High fat and high sugar in any food can lead to health problems. So, a low-fat and low-sugar yogurt product, like a low-fat Greek yogurt, would be ideal if you’re looking to keep healthy.
Yogurt products incorporating fruit or nuts can provide additional nutritional and health benefits, but many of these can also contain added sugar. Adding fresh fruit or nuts to a yogurt yourself is a healthier option.
If you would like to have probiotic effects, you can choose a product with acidophilus or bifidobacteria.
You should check the product label as it is a legal requirement to list all the ingredients, cultures and nutritional information in commercial yogurts.
When it comes to probiotic yogurts, it’s always better to choose a fresh product rather than one closer to the expiry date, as probiotics die during storage.