Rosemary Stanton

Nutritionist

Debunking the "Low Carbohydrate" Myth, and Wholegrains in the Australian Diet

Wholegrains are being rejected by some people because they occur in carbohydrate-rich foods. Current popular diets reject carbohydrates, blaming them for excess weight and promoting higher intake of protein instead. There is also a tendency to blame wheat for all ills, and as wheat is the most common grain used in Australia, its omission can reduce wholegrain intake.

Some of the popular low carbohydrate diets include the Zone diet, Protein Power, Dr Atkins Diet and Sugar Busters!

The Zone diet is probably the best of these, but its recommendations differ from those of most health authorities as follows:

Table 1.  % Energy

Those selling diets are always looking for new diets and the current crop produce a fast initial weight loss by depleting muscle glycogen levels and their associated water. There is also a belief that low-fat diets don't work, since everyone claims to be eating less fat, but the population is getting fatter.

There are also some specific anti-grain messages, with claims that grains and cereals have only been used for only 10,000 years, humans not genetically able to handle grains and grains and cereals increase insulin levels, causing excess weight and diabetes.

These messages do not make nutritional sense. Although humans have only used grains/cereals for 10,000 years, excess weight and high levels of Type 2 diabetes did not occur for the first 9,950 of those years. And in Asian countries where grains have dominated the diet, excess weight and diabetes have been rare. Both are now occuring as Asian countries cut back on grains and increase their consumption of Western-style high-fat foods.

The claim that humans are not genetically equipped to handle grains also ignores the fact that some hunter gatherer societies used the seeds of wild grasses and, in Australia, ground up acacia seeds to make flour. The fact that some of our ancestors had high protein diets with relatively little carbohydrate only shows that humans can adapt to a wide range of diets.

The claim that grains and cereals increase insulin levels and this then leads to weight gain and diabetes also ignore the fact that excess weight usually precedes increased insulin levels and diabetes. It is also much easier for the body to store dietary fat as body fat than it is to convert carbohydrate into body fat.

There is evidence that wholegrains are protective against some cancers, diabetes, coronary heart disease and obesity. It is also difficult for many people to get enough dietary fibre without grains and grains are excellent sources of vitamins, minerals, protein, essential fatty acids and phytonutrients.

Low carbohydrate diets also misinterpret information about dietary fat intake, assuming it has decreased, on the basis of poor evidence. Although more fat-reduced foods are available, there are also more high-fat foods being sold. One third of the food dollar is now spent on foods bought and consumed outside the home, with most having a high fat content. We also have evidence that most people under-report their food intake and selectively under-report foods high in fat.

Health professionals also underestimate portion sizes as is obvious by comparing the assumed fat content from various countries' data bases and the actual figures calculated from popular recipe books and from recipes supplied by owners of cafes and restaurants.

Table 2.

There is also data from New York showing discrepancies between dietitians' estimate of the fat content of portions of food and subsequent analysis of the portions they had seen.

Table 3.

Source: Prof M Nestle, Resources for Food Science & Human Nutrition Information, 1997, 97-2

There are practical problems associated with low-carbohydrate diets. These include higher levels of fat (including saturated fat) and unnecessarily high levels of protein. In theory, fat would not rise if fish as chosen as a major source of protein, but the world's fish stocks cannot stand any increase in consumption. When most people cut out cereals and breads, their substitute choices also tend to be less nutritious, for example, pastries may be used in place of breakfast cereals and children may have crisps and snacks instead of a sandwich at lunchtime.

There are also environmental effects of cutting back on grains. Without them, we could not feed current world population. Using grains to feed animals and then eating the animal flesh is ecologically wasteful.

Figures are also available to illustrate wise use of land

Table 4.

Grains and cereals also use less water for their production.

Table 5.

Note: In both the above tables, animals are lot-fed.

In summary, low-carbohydrate/low grain diets are not recommended. They are inappropriate for reducing obesity, can reduce muscle glycogen stores and go against dietary guidelines recommending more grains. Most cancer experts also recommend we consume less meat and more plant foods. Restricting wholegrains also leads to a fall in fibre intake, reducing protection for many gastrointestinal problems and cancers.

Can we improve carbohydrate intake? Yes, by:

• reducing sugar and refined carbohydrates, and
• choosing more wholegrain products - for more dietary fibre, more minerals, more vitamins, essential fats and phytochemicals.