Yoghurt
We’re often told that yoghurt is meant to be good for us, but are all the manufacturer’s amazing claims actually true? Yes, maybe and no.
It used to be easy to choose a yoghurt. Long ago you went to a health food store, which was the only place where you could buy it, and it was simply, naturally plain. Now there are literally dozens of different yoghurts to choose from. They may have regular levels of fat (about 4%), slightly higher fat levels (usually 7%) or, in the case of the luscious, extra-thick European yoghurts, 10% fat. In the other direction, there are reduced-fat (2% fat) or even non-fat varieties.
Yoghurt in Australia
Unlike the situation in Europe, where natural, unflavoured yoghurts dominate sales, most yoghurt sold in Australia is sweetened and flavoured. Flavouring choices include fruit, artificial flavourings, sugar or artificial sweeteners. The ingredient list will tell you what your choice contains. Some yoghurts also contain gelatine, which makes them set to a firmer texture.
Although yoghurt is now a mainstream product, research from the Australian Dairy Corporation shows that more than 40% of Australian men have never tasted it. Yet most women and children of both sexes consider it a normal part of their diet.
Origins
Yoghurt has been used as a food for so long that its origins are clouded in legend. The Bulgarians and Turks both claim it started life in their regions with nomads. The story is told that long ago, some nomads wandering in the desert somewhere in the Middle East were supposed to have placed some milk in a leather pouch, newly made from a sheep’s stomach. The bacteria present in the pouch, plus the steady warmth of the day, curdled the milk which then set to a delightful creamy texture in the cool of the desert night.
Make it yourself
Yoghurt is basically made from pasteurised milk with an added bacterial culture that thickens the milk. You can make it yourself by warming a litre of milk to blood heat, adding a spoonful of yoghurt, mixing well and leaving it at that temperature for a few hours. A special wide-mouthed thermos jar makes this easy (you can buy yoghurt-makers commercially). Once the yoghurt sets, you put it in the refrigerator. The bacteria that thicken the milk stop undesirable bacteria growing, at least for a time.
Good and bad bacteria
It’s the presence of ‘friendly’ bacteria in yoghurt that has recently launched a raft of claims from manufacturers about the health benefits of yoghurt. Before we sort through these various claims, we need to know how bacteria work, both inside our stomach and intestines, as well as within yoghurt itself.
The human gastrointestinal tract contains billions of bacteria, which can be divided into more than 200 different species. These carry out many functions, ranging from breaking down dietary fibre and undigested starch to synthesising vitamins and regulating the time food residues stay in the intestine. Their presence also stops many undesirable bacteria taking up residence. Sometimes, however, harmful bacteria can overpower normal bacteria. This is what happens when you suffer an attack of diarrhoea.
Those people marketing products containing ‘good’ bacteria hope that their products will provide bacteria that are even better at fighting the ‘bad’ guys than the normal bacteria in your stomach and intestines. Some of these ‘good’ bacteria seem to work in the test tube, but whether they can colonise the large intestine when taken as yoghurt or a small bottle of fermented sweet liquid is another matter.
More hype than proof?
The bacteria traditionally used to thicken milk into yoghurt were Streptococcus thermophilus and Lactobacillus bulgaricus. These two varieties do not seem to be able to survive digestion and attach themselves effectively to the human intestine, although they are still used in many good-tasting yoghurts.
Some of the newer products now use a variety of bacterial cultures which may be listed as Lactobacillus acidophilus, bifidobacteria, GG or LC1 (which are specific strains of lactobacillus). Scientists call these probiotics.
For most of the health claims implied by sellers of yoghurts and related drink products, the hype currently outstrips the proof. Many of the claims sound possible, but there have not yet been enough proper trials in the body, as opposed to the test tube, to prove that the hoped-for effects actually do occur.
Surviving the test
The modern marketing excitement about yoghurt usually concentrates on the strain of bacteria used. Without making specific health claims about their products (because doing so is still illegal), manufacturers of yoghurts and related fermented drinks have implied that their products have benefits over and above their nutritional value. But how valid are these implications?
There is no simple answer and there are lots of ‘ifs’ in all this. But there is evidence that some of the strains of bacteria added to some yoghurts may be useful. It is also unknown whether yoghurts with these bacteria will help problems such as constipation, irritable bowel syndrome, allergies and anything which adversely affects the body’s immune system. Nor do we have proof that these products can counterbalance any adverse side-effects of antibiotics which wipe out good bacteria along with bad ones.
Lots of goodies
In the meantime, while we await some more proof about its bacterial benefits, it makes sense to eat more yoghurt – because it’s a good source of nutrients, such as calcium, protein and riboflavin. These important nutrients come from the milk used to make it. Since most products are made from milk plus concentrated skim milk, the nutrient content is even greater than an equivalent quantity of milk. However, the small bottles of fermented drinks do not have the advantage of the high nutrient content found in yoghurt.
Further reading
For more of Rosemary Stanton’s advice on food and nutrition consult: Rosemary Stanton’s Complete Book of Food & Nutrition (Simon & Schuster, revised edition 1995, rrp $29.95)
Eating for Peak Performance by Rosemary Stanton (Allen & Unwin, second edition, 1994, rrp $16.95)
Healthy Vegetarian Eating by Rosemary Stanton (Allen & Unwin, 1997, rrp $6.95)
