Bury the bread and potatoes myth

Press, 25 June 1983, Page 12

Bury the bread and potatoes myth

Good eating

Janice Bremer DIETITIAN

Diet-conscious people are reading the new nutritional messages giving a green light to eating more cereals, grains, vegetables and fruit. But has the old myth — the red stop sign on bread and potatoes — been shattered and left to die? Eating more fibrous starchy foods to reduce the risks of disease conflicts with the low-starch “diets” of our popular press in the recent past, thrusting us into a dilemma of decisions. But the popular fables claiming “a pound of weight loss each day” can be explained: The fact: — A temporary and rapid weight loss can be achieved if sjigars and starches are removed from the diet, but this procedure is nutritionally unsound and potentially dangerous in the longterm. The fallacy: — This weight loss is not sustained if sugars and starches are reintroduced into the diet, or if total energy (or calories) are not kept lower than before the “diet.” Our fancy:— Deprived of the foods we like on such a diet, we eat less food anyway — the key to weight loss is less food energy or calories. Such “diets” fail because most people cannot cut out their favourite foods forever. Carbohydrates and health Carbohydrates are the sugars and starches present in our foods. As well as causing a' weight problem, the eating of carbohydrates has been

implicated as a cause of flabbiness, low-blood sugar, tooth decay, fatigue, depression, lack of sleep — a deadly threat to life and health! Carbohydrates, in particular sugars, have also been investigated as a cause of diabetes, heart disease, gout, kidney stones, ulcers, cancer, infections and many other complaints. No conclusive evidence indicting all carbohydrates can be found. The anti-carbohydrate literature probably began when a greater understanding .of the condition of diabetes demonstrated that carbohydrates caused surges in blood sugar levels (because of an impaired ability to handle sugars). However, people without diabetes seem to be able to handle moderate amounts of sugar in their diets. In the 1950 s the anticarbohydrate story grew when carbohydrates were blamed for hypoglycae-

mia, or low blood sugars. Then in the 1960 s — the “Twiggy” era — weight reduction began to become the preoccupation of our society that is sustained today. The “low carbohydrate diet” gave fast, short-term results. It is unfortunate that the types of carbohydrate have not been well defined because it is the sugars as differentiated from starch, that appear to hold the detrimental qualities acclaimed to carbohydrates. It is “added” sugars that upset blood sugar levels, and it is “added” sugar that causes an unwitting high energy (high calorie) consumption causing weight gain. Carbohydrate energy It is commonly known that sugar provides energy. But energy is derived from most foods. Our food energy begins with plants. When we eat meat or milk the energy so supplied comes originally from the grasses the animal has eaten. Plants derive their energy from the sun. by juggling the basic elements of life, carbon, hydrogen or oxygen to ultimately combine carbon and water (hydrogen and oxygen). This final mixture is called hydrated (combined with water) carbon or carbohydrates. These carbohydrates in plants can be grouped into sugars and starches. The simplest form of sugars most widely occurring in natural plant foods are glucose (also called dextrose or corn sugar) and fructose (fruit sugar). A combination of glu-

cose and fructose, is sucrose which is also the sugar we know as table sugar. Our major natural sources of fructose, glucose, and sucrose are fruit and vegetables. The only significant source of naturally occurring animal sugar is milk sugar or lactose which is made up of galactose and glucose. Many different types of sugars can be commercially manufactured from these sugars. Starches are complex combinations of sugars formed by plants as energy stores when vegetables or grains mature. We can taste the result of starch formation in that older potatoes or peas are less sweet than the new vegetables because more starch has been made from the sugars. The breakdown of this starch back into those original sugars, occurs during the digestive processes of our intestines. Other non-starch combinations of sugars joined together form fibre, or the structural part of plants, but our bodies are less able to break these down into the original sugars. Cautions for high-carbo eating It is now advocated by health authorities, the cancer reports, and heart disease reports that carbohydrates should form half of our daily food energy. These are in favour in sports medicine as the preferred fuel for training athletes, and are essential to provide the fibre foods of a high fibre diet. But still we must be

wary of the different types of carbohydrates. Sucrose is really the “baddie” — or some would say “goodie.” Nutritionists have searched in vain to pin on it disease caused through excessive consumption. Apart from dental decay — and then only if it is eaten as a “sticky” food and not cleaned off the teeth — they have been hard put to find proof of detrimental effects. But questions of nutrition arise in the new highcarbohydrate, low-fat eating style: ® Does the eating of refined starches (white breads, processed breakfast cereals) supply sufficient of minerals and vitamins if they displace meat in the diet? © If sugar remains a part of the diet can nutrient needs be met by sedentary people with low energy needs? ®Do refined carbohydrate foods really cause weight gain as compared with high fibre, bulky carbohydrate foods? At present we probably eat only 40 to 45 per cent of our daily energy as carbohydrate. Of this, 36 per cent is as baked goods, sugar syrups, jams, honey, desserts and soft drinks. All are refined foods and relatively poor sources of other nutrients. Just over 50 per cent of our carbohydrate energy is in bread, cereals, fruit, vegetables and milk. But we can make a nutritionally sound and palatably acceptable change so that these foods form 80 to 100 per cent of our carbohydrate consumption. High carbohydrate foods should be eaten as unprocessed and intact as possible, retaining the total nutrition originally supplied in nature. Evidence at last Dr Ken Heaton, from .Britain, who visited New Zealand last year for the International Fibre Symposium, has very recently published evidence that the consumption of refined foods, rather than unrefined foods, leads to a lower intake of nearly all of the vitamins and minerals recorded in tables of food consumption. He has also shown that

the inclusion of refined foods “unwittingly inflates” energy or calorie consumption — direct evidence of this has been previously lacking. Dr Heaton studied people when they ate as much as they liked of unrefined foods in one period and largely refined foods in another period. On the refined carbohydrate diet they ate 23 per cent more calories, and put on weight. People with diabetes, studied in the same way, did not have more calories in either period because they did not eat sugar. The study concluded that the blame for more calories rests wholly on the higher sugar intake on the refined diet. However, both groups had a considerably lower fibre, vitamin, and mineral intake on the refined diet. For some nutrients, this meant a marginal adequacy or even a deficiency. IMPORTANT MESSAGES @ In the manufacture of refined carbohydrate foods such as sugar and white flour, other substances besides dietary fibre are removed. 0 When we eat less of meats and fats, it is important that replacement is not made with refined carbohydrate foods. © A diet high in refined sugars usually also includes associated refined fats, included in the processing methods of such foods. Refined carbohydrates are: ® Calories that can be consumed so rapidly that the normal body mechanisms do not register that enough food is eaten. We might manage apple pie

and ice cream when we are already full from a main course only because it does not appear to be much to eat. However, we would hardly contemplate eating the equivalent of calories as seven or eight apples! • Average size servings of food naturally rich in starch or sugars rate lower for calorie value than protein or fat foods. For 100 calories we may eat 50g of bread (2 slices), 280 g or 2 medium apples, 125 g potato (2 small), 50g of grilled meat (% steak), 37g of sausages (% of one), 25g Cheddar cheese (1 thin slice). • Many so-called “carbohydrate” foods are in fact largely fat — pancakes, custard tarts, sponge cake, or chocolate biscuits have 50 per cent of their calories as fat, potato crisps 60 per cent, flaky pastry 65 per cent, and cheese’ cake 75 per cent! ® Watch what goes onto starchy staples — a thin slice of bread liberally spread with butter or margarine and a slice of cheese has 70 per cent of calories as fat. • Bread, potatoes, pasta, rice and other grain or starchy foods as eaten in "whole” style are the most appropriate foods to form the base of nutritious meals and should have first priority in the menu choice. They are the staple foods for a normal balanced diet as well as for a food intake designed to facilitate weight reduction — just less of it. Fruit and vegetables make up the complement of carbohydrates. As a last note — legumes or pulses, as discussed in an earlier column, can provide the missing nutrients in a diet devoid of animal foods. However, most New Zealand nutrition experts, in recommending less fat and more “whole” carbohydrate rich foods, do also emphasise the value of animal foods, in particular, low-fat varieties that are richer in other essential nutrients in our New Zealand diet. In my next column I will discuss further how nutrient needs are best accounted for when changing from a high fat, high animal protein diet to meals composed largely of carbohydrate.