EAP Publication - 35
Nutrition of fresh milled bread vs. mass produced bread
NUTRITIONAL CHARACTERISTICS of ORGANIC, FRESHLY STONE-GROUND, SOURDOUGH & - CONVENTIONAL BREADS
by
Judy Campbell, B.Sc.,
Mechtild Hauser,
and
Stuart Hill, B.Sc., Ph.D., P.Ag.,
INTRODUCTION
Consumers concerned about their health are changing their dietary habits. Yet most are unaware of the potential nutritional value of bread, which makes up a major part of their diet. However, comprehensive information concerning this topic is not readily available. This paper compares the nutritional characteristics of organic, freshly stone-ground, sourdough breads with conventional breads, highlighting the factors which inhibit or enhance its nutritional value.
A brief history of wheat, its milling, and bread-making are included to enable the reader to better understand factors that are responsible for the decline or the improvement of the nutritional quality of bread.
IMPORTANCE OF WHEAT AND BREAD
Cereal grains and legumes play an important role in supplying the nutrients, as well as over 70% of the daily energy requirements, of over two-thirds of the world's population (Edwards et al. 1971). A Nationwide (USA) Food Consumption Survey in 1977-78 found that cereal product consumption was equivalent to 226 grams of flour per day for men and 156 grams for women (Guthrie, 1989). Bread, the most common form of cereal intake in many countries has been designated the Staff of lifer, and rightly so, since it contains more nutrients per weight than meat, milk, potatoes, fruits, and vegetables (Thomas, 1976).
Egyptians are believed to be responsible for introducing the process of leavening around 4000 B.C. (Spicer, 1975). For a long time, bread was in fact central to their economy, as wages and bills were often paid in the form of dough (Bread Winners, 1978).
Bread may be made from various cereals, grains, and legumes. Wheat, being the oldest cereal known to man (Jenkins, 1975), is the most common. Today, wheat is the world's dominant cereal crop (Davidson & Passmore, 1986). Total world production is about 250 grams per person per day. In its unrefined state this could supply 800 calories and 30 grams of protein per person were it evenly distributed worldwide (Davis, 1981). This amount would also supply a 25 to 49 year old man with 30% of his energy requirements and 49% of his protein requirements (Health & Welfare, 1990). Although wheat consumption in the US decreased until the early 1970s, it has since stabilized (Pomeranz, 1988). Wheat-based foods now supply only about 20% of the daily energy requirements of US citizens but are the main source (30%) of dietary fibre in the USA (Anderson, 1985).
Wheat's pleasant flavor, long shelf-life, and unique gluten-forming characteristics (Nelson, 1985) make it the most popular grain for bread-making. Other grains used include barley, millet, oats, and rye, as well as nuts and acorns. As a result of wheat- breeding, many of the early wheat varieties, including emmer and spelt, were neglected and are little known today. Wheat breeding focused on improving both crop yield and baking qualities. In Germany, 1000-grain weight has increased by about 40% between 1938 and 1971, resulting in a larger wheat endosperm - and therefore proportionally more starch and protein, yet less vitamins and minerals (Thomas, 1990).
Rye is a grain commonly used for bread-making in some European countries and in the Soviet Union (Jenkins, 1975), partly because rye produces higher yields on poorer soils than does wheat.
NUTRITIONAL VALUE OF WHEAT AND RYE
The kernel of wheat is composed of the outer bran layer, the germ, and the endosperm. It is rich in nutrients, many of which are concentrated in the bran and germ. Of special importance is that it contains the entire B complex, except for vitamin B12. B vitamins function as cofactors in many metabolic reactions involved in the release of energy (Birdsall, 1985).
The germ, which includes the scutellum, is especially rich in vitamins B and E, high quality protein, unsaturated fats, minerals, and carbohydrates. The bran consists mostly of the insoluble carbohydrate cellulose, and contains incomplete protein, traces of B vitamins, and minerals - especially iron. The endosperm is the largest part of the grain, and consists mostly of the carbohydrate starch, incomplete protein, and trace amounts of vitamins and minerals.
Significant variations in the content of grains occur because of variety, crop year, area, fertilizer, and soil type. It must therefore be kept in mind that values expressed in tables reflect average values. The following table, taken from Guthrie (1989), shows the percent distribution of the major nutrients in cereal grains.
The following table of data for the major components of wheat was taken from Souci (1981). Values are in grams per 100 crams of the grain portion referred to, except for minerals quantities which are expressed in milligrams and the energy units which are kilocalories and kilojoules.
Because of its high content of vitamin E, wheat germ is promoted as a health food, and has been proposed as a cure for almost every disease. Recent studies have shown that vitamin E increases the desirable HDL cholesterol in women, though in men only if they initially had low levels. Animal studies have also shown that vitamin E protects against free radicals released by the body when it is exposed to toxic chemicals. Vitamin E is used to treat intermittent claudication, which involves cramps in the calf muscles at night and extreme pain while walking. Vitamin E may be helpful for fibrocystic breast disease (Guthrie,1989).
Other vitamins and numerous other minerals are found in the wheat kernels, though in small amounts. These include carotene, vitamin B6 or pyridoxine, pantothenic acid, biotin, and folic acid, vitamin C, and vitamin K. Other minerals are sodium, calcium, chlorine, manganese, zinc, copper, cobalt, nickel, chromium, molybdenium, fluoride, iodine, boron, selenium, lead, aluminum, and siliconioxide (Souci, 1981). The body is capable of converting the carotene to produce one sixth its amount as vitamin A (Health ~ Welfare, 1990).
The nutritional value of wheat is improved by milling, which increases its digestibility, and by moderate heat and humidity which inactivate enzyme inhibitors and other heat-sensitive toxic factors, and denature protein (Nierle, 1984).
Despite all its many nutritional qualities, wheat cannot meet all nutritional needs. Since it lacks adequate amounts of certain essential nutrients - vitamins A, B12, and C, fats and the amino acid Iysine. These must come from other sources.
The quality of a protein is determined by the kind and composition of its constituent amino acids. When all essential amino acids are present in the proportions capable of promoting growth, the protein is complete, of good quality, and of high biological value (BV), and would result in a high net protein utilization (NPU) by the body. If a protein has a relatively small amount of one essential amino acid (called the limiting amino acid), body tissue repair will occur, but growth cannot be supported (Guthrie, 1989).
Lysine is the limiting essential amino acid in cereals. A greater intake of Iysine than that found in wheat is especially important for children. Wheat protein is adequate for adults, since they have been shown to maintain nitrogen equilibrium (intake of nitrogen from protein = loss), or to be in slightly positive nitrogen balance (intake = loss) when consuming bread diets (Bolourchi et al., 1968; Betschart et al., 1985; Young and Pellett, 1985). The requirements for Iysine are about three times less for adults than for children (Thomas, 1986). Protein from rye has a higher biological value (or net protein value which is net protein utilized) than does wheat because of its superior amino acid composition (Mender, 1983). Wheat contains about 20% to more protein than rye. However, rye contains 30% more of the amino acid Iysine than does wheat. Rye also contains more calcium and fluoride (Thomas, 1986).
To assure an adequate supply of Iysine, bread made solely from grain should be consumed in combination with milk products, meat, nuts, or legumes. There is a need for some animal products, since they are the only sources of vitamin B12, apart from intestinal bacteria capable of producing some (Thomas, 1986). Large deficiencies of this vitamin lead to anemia (Guthrie, 1989). Fruits and vegetables are required to provide the missing vitamins A and C, and fats are needed to supply essential fatty acids, because wheat and rye contain very little fat (about 2%).
Component
|
Endosperm
|
Bran
pericarp/aleurone
|
Germ
|
Scutellum
|
| Protein |
72
|
4/15
|
3
|
5
|
| Total Mineral |
20
|
7/61
|
4
|
8
|
| Vit B1 (thiamin) |
3
|
1/32
|
2
|
62
|
| Vit B2 (Riboflavin) |
32
|
5/37
|
12
|
14
|
| Niacin (a B vitamin) |
12
|
4/82
|
1
|
1
|
| Vit B6 (Pyridoxine) |
6
|
12/61
|
8
|
12
|
| Pantothenic Acid |
43
|
9/41
|
3
|
4
|
The following table of data for the major components of wheat was taken from a book by Souci (1981). Values are in grams per 100 grams of the grain portion referred to, except for mineral quantities which are expressed in milligrams and the energy units which are kilocalories and kiloJoules.
| Component | Endosperm | Germ | Bran |
| Carbohydrates | 74.0 | 46.0 | 51.2 |
Starch
|
72.5 | 10-30 | 12.2 |
Fibre (insoluble)
|
3.3 | 8.1 | 45.0 |
| Protein | 10.6 | 26.6 | 16.0 |
Lysine
|
0.25 | 1.62 | 0.64 |
| Fat | 0.98 | 9.2 | 4.65 |
| Minerals | 0.35 | 4.2 | 4.15 |
Phosphorus
|
108 | 1100 | 1240 |
Potassium
|
108 | 837 | 1390 |
Magnesium
|
21 | 250 | 590 |
Iron
|
1.95 | 8.1 | 12.9 |
| Vitamins | |||
| B1 (thiamin) | 0.06 | 2.01 | 0.65 |
| B2 (riboflavin) | 0.03 | 0.72 | 0.51 |
| Nicotinamide (or niacin) | 0.7 | 4.5 | 17.7 |
| E | 2.3 | 27.6 | 9.1 |
| Water | 13.9 | 11.7 | 11.5 |
| Energy (kcal/KJ) | 355/1490 | 346/1450 | 188/789 |
STONE-GRINDING OF GRAIN
In the third century B.C., rotary grindstones powered by animals, and small rotary hand mills called querns, replaced stone or wooden mortars and pestles for the grinding of grains. Querns are still used in rural areas of the Middle East, Far East, and parts of Africa (Hall, 1974).
There are several advantages to stone-ground wheat flour. The endosperm, bran, and germ remain in their natural, original proportions. Because the stones grind slowly, the wheat germ is not exposed to excessive temperatures. Heat causes the fat from the germ portion to oxidize and become rancid and much of the vitamins to be destroyed (Aubert, 1989). Since only a small amount of grain is ground at once, the fat from the germ is well distributed which also minimizes spoilage (Mount, 1975). Nutritive losses due to oxygen exposure are also limited by the fact that stone-ground flour is usually coarser (Thomas, 1976). As expressed in The Bread Book (Leonard, 1990), stone-ground flour is preferred by many bakers and natural food advocates because of its texture, its sweet and nutty flavour, and the beliefs that it is nutritionally superior and has a better baking quality than steel-roller-milled flour. Moritz and Jones (1950) and Schultz et al. (1942) showed that stone-milled flour was relatively high in thiamin, compared to roller-milled flour, especially when from hard wheat.
ADVANTAGES OF FRESH FLOUR
Because grains contain only about 12% water (or about 0.6 water activity), they are not predisposed to spoilage. However, grinding removes the protective layers and endangers the grain's biological stability. Deterioration of sensory and nutritional qualities depends on storage conditions, such as temperature, humidity, oxygen concentration, and light exposure. The lower the water activity, the lower is the loss of vitamins (Munzing, 1987). For example, a vitamin E loss of only about 23% occurred after a 13 months of storage at a 0.6 water activity (Rothe 1963, Plasch 1984, Pelschenke 1961). In order to reduce oxidation of Essential compounds and the development of rancidity, many authors recommend storing ground flour for no more than two weeks (Solder 1984, Bruker 1984, Schnitzer 1986, Schnitzer (no year), Thomas 1982, Thomas 1986, Koerber 1986). Antioxidants present naturally in grains (vitamin E and lecithin) help prevent oxidation of the fatty acids and the associated rancidity only for a limited time, and under 'favourable' conditions.
Glutamic acid decarboxylase, the most sensitive enzyme in the grain, is used to indicate the health of the grain. When heated or exposed to increased humidity, even under 'favourable' conditions, it losses activity very quickly in wheat. It was found to be even more sensitive in rye (Muzing, 1987).
The B vitamins are liable to be destroyed by light and air, and it also seems that other substances, still unknown, are quickly destroyed (Aubert, 1989). Other deteriorations include denaturation of lipoproteins, phospholipid hydrolysis, auto-oxidation of unsaturated fatty acids of phospholipids, polymerization within lipoproteins, browning, Maillard reaction of amino groups from phospholipids and aldehyde groups from sugars, and carotene and aroma losses (Lea, 1957; Thomas, 1976).
Lipids in milled wheat are much more susceptible to enzymatic degradation, because enzymes are incorporated into the flour with fragments of bran and germ and with microorganisms from the surface of the grain. Associated with lipid deterioration are losses of carotenoids and vitamin E (Galliard, 1983).
The nutritional importance of using fresh stone-ground grains for bread-making was revealed in the results of feeding studies in Germany (Bernasek, 1970). Rats were fed diets consisting of 50% flour or bread. Group 1 consumed fresh stone-ground flour. Group 2 was fed bread made with this flour. Group 3 consumed the same flour as group 1 but after 15 days of storage. Group 4 was fed bread made with the flour fed to group 3. A fifth group consumed white flour. After four generations, only the rats fed fresh stone-ground flour and those fed the bread made with it maintained their fertility. The rats in groups 3 to 5 had become infertile. Four generations for rats is believed to be equivalent to one hundred years in humans.
Different ecological standards for flour storage set limits of 15 to 60 days (Picker & Pedersen, 1990), although rancidity has been detected as early as 2 to 14 days after milling (Larsen, 1988). Nutrient analysis studies are required to determine the exact nutrient losses accompanying the development of rancidity and thereafter.
DEVELOPMENTS IN THE MILLING OF GRAIN
The Egyptians were the first to use a selective milling system. With hand sieves, they separated the flour from large bran particles, dirt, and stone chips that had broken off their implements (Davis 1981; Hall 1974; Marine & Van Allen 1972). Stone chips are not a problem with modern mills. In 1950, the degree of contamination of stone-milled flour with stone-dust was shown to be so slight as to not alter the mineral content of flour markedly (Moritz et al., 1950).
Since Roman times, white flour and bread have been regarded as the foods of upper classes. Flour, however, was far from white compared to today's flour (Marine & Van Allen, 1972). It was not until the 19th century that major changes in the milling processes took place.
The earliest version of today's iron roller mills were first used in Hungary in 1839. Between 1870 and 1890, they quickly replaced the stone mills throughout Europe and North America, and milling soon became completely automated (Davis 1981; Hall 1974). The roller mills were more economical and more efficient. The milling process could be controlled to produce as white a flour as the public demanded (Mount, 1975). However, the resulting flour was devoid of bran and germ, and consequently many nutrients were lacking.
MILLING TODAY
A very sophisticated process is currently employed for the milling of grain. Cleaning is accomplished by means of separators, aspirators, scourers, magnets, and washer-stoners. The wheat is tempered or conditioned in water to toughen the bran to reduce fragmentation when it is removed, and to obtain a moisture content resulting in particles of the desired size. The processes of drying and conditioning rye with steam (25% humidity and 60°C), have been shown to cause minerals such as potassium and phosphorus migrated to the endosperm, whereas more strongly bound minerals like calcium and magnesium did not migrate (Pelshenke, 1970). This may increase the content of certain minerals in refined flour. During the milling process, steel rollers crush the grain, and the flour released from the endosperm is separated by sifters into different grades or streams, according to fineness. Each of these has different mineral and protein contents, and may be recombined later to form a variety of flours to be sold for diverse baking purposes (Jenkins, 1975; Davis, 1981). The bran and germ, which make up about 28% of the wheat, are totally removed in this process. They are used in the production of animal feeds (Davis, 1981), as -well as by pharmaceutical laboratories for making diet supplements (Sablier, 1984).
Whole wheat flour is produced by recombining ground bran with endosperm flour, but the germ is usually left out, because it would go rancid. The resulting flour may represent only 95% to of the total grain (by weight), or in other words a 95% extraction (Day, 1966)
About 95% of the flour used in the USA is white and of only about 72% extraction. Only 20 to 30% of the grains original vitamins are retained, and the protein content is about 1 - 1.5 To lower. However, since bran decreases protein digestibility, the available protein does not significantly change (Pomeranz, 1988; Nierle, 1989). The NPU is similar in 66 to 100% extractions (Pedersen and Eggum, 1983).
ENRICHMENT OF FLOUR
In the 1940s, a flour enrichment program was instituted to compensate for wartime shortages of other foods. However, in the 'enriched' flour only the B vitamins - thiamin, riboflavin, and niacin - and the mineral, iron, were added, in amounts approximately equivalent to those removed from whole wheat (Jenkins, 1975). Flour 'Enrichment' implies a loss of nutrients and should not be equated with wholesomeness. For approximately 20 nutrients, there is an average loss of 70-80% to in refined and enriched flour (Davis, 1981). Its consumption clearly places the body at a disadvantage, casting a burden on the rest of the diet. The addition of more nutrients to refined flour has been considered, but it is limited by, for example, the effect of some nutrients on sensitive individuals (Pomeranz, 1988).
Since research is incomplete concerning nutrient requirements, interactions, optimal ratios, and toxicities (Allison et al., 1980), many believe that the safest option is to consume flour containing the nutrients in their natural proportions.
ADULTERATION OF FLOUR
As with most raw commodities, grains included, processing is the primary means used to maintain and increase market share. Typically, relatively little time and money is invested to examine possible health implications of such processing. Concerning grains, the separation of the milling and baking industries has led to the adulteration of flour with various chemicals, as flour manufacturers have sought to maximize profits and meet customer demands. For example, removing the germ not only prevents flour spoilage, it generates profits when sold to millfeed producers and pharmaceutical companies.
For centuries, bakers have known that 'good quality' baked goods could not be made with freshly milled flour, because the dough would lack strength and resilience to trap gas. Until the 20th century it was common practice of storing flour for months to allow oxygen to condition it. However, as well as storage costs, spoilage and insects caused losses. Chemical oxidizing agents or bleaches were developed to produce the same aging effects in 24-48 hours (Baker's Digest, 1962). They cause one of two effects: oxidation of the gluten (so less sulfhydryl groups are left to disturb disulfide bonds that need to form during dough fermentation for the bread to rise), and bleaching of the yellowish carotene pigments which could have been sources of vitamin A (Thomas, 1986; Jenkins 1975; Freeland-Graves & Peckham, 1987).
Bleaching agents did not come into use without opposition. A 1954 issue of the National Police Gazette, reports that, Harvey W. Wiley, Chief of the Food and Drug Administration early this century, won a Supreme Court decision outlawing bleaches, but he Was forced out of the FDA, and the Supreme Court order was bypassed through administrative actions. The approval of chlorine dioxide as a bleaching agent was not without protests by U.S. Army nutrition experts (Rorty, 1954).
Today, the Canadian Food and Drug Act and Regulations Division 13, B.13.001 permits the addition of numerous chemicals to white, whole wheat, and rye flours (Daniels, 1978). These include chlorine, chlorine dioxide, benzoyl peroxide, potassium bromate, ammonium persulfate, ammonium chloride, acetone peroxide, azodicarbonamide, ascorbic acid, l-cysteine, mono-calcium phosphate. Regulations also specify the acceptable levels. The addition of a variety of chemicals to bread is also permitted in the USA, but in many European countries the use of additives is almost completely prohibited (Jenkins, 1975). In Germany, for instance, chemical oxidizing agents were banned in 1958 (Marine & Van Allen, 1972).
Nitrogen bichloride, also known as agene, was one of the earliest bleaching agents. After 40 years of use, it was finally found to cause canine hysteria, and was outlawed (Rorty, 1954). The currently most common bleaching agent is benzoyl peroxide. It must be neutralized by adding such substances as: calcium carbonate (chalk!), calcium sulphate, dicalcium phosphate, magnesium carbonate, potassium aluminum sulphate, sodium aluminum sulphate, starch, and tricalcium phosphate.
The most common maturing agent in use is potasssium bromate, and it is added with carriers such as calcium carbonate, dicalcium phosphate, or magnesium carbonate. An alternative method to oxidize the flour to cause the same improvements in bread quality, is overmixing the dough three to four times normal to bring it in contact with oxygen. The lipoxidase enzyme in wheat germ or in soya flour, if it is added, uses the oxygen to oxidize the flour (Horder et al., 1954).
In addition to the chemicals permitted to be added to flour, many more are permitted to be added to bread before baking to facilitate the manufacturing process, to produce a light texture, and to improve conservation quality. These chemicals include emulsifiers, conditioners, and preservatives (Hall, 1974). At the present time, the Health Protection Branch in Canada allows the addition of almost 30 different chemicals, in limited quantities, to flour and bread. Yeast may also contain the Yeast foods additives: calcium sulfate and ammonium chloride (Aubuchon, 1990). Chemicals likely to be found in conventional breads include: lecithin, mono- and di- glycerides, carragheenan, calcium sulfate, calcium carbonate, dicalcium sulfate, ammonium chloride, potassium bromate, calcium bromate, potassium iodate, calcium peroxide, azodicarbonamide, tricalcium phosphate, monocalcium phosphate, calcium propionate, sodium propionate, sodium diacetate, lactic acid, calcium stearoyl-2-lactylate, lactylic stearate, sodium stearyl fumarate, succinylated monoglycerides, ethoxylated mono- and all-glycerides (Marine & Van Allen, 1972)
In Germany, propionic acid, sodium propionate, calcium propionate, and potassium propionate have been banned as preservatives since March 1988. This was in response to earlier experiments which found that rats fed these substances developed tumors. These results have been questioned, however, because the tumors were reversable. Nevertheless, the German government decided that as few additives as possible should be found in food, and therefore saw no need to reverse their decision ("Nach..." 1987, "Jetzt..." 1988).
A topic receiving more attention, as people become more concerned about the foods they eat, is food irradiation. Approval for irradiation of wheat and wheat flour for disinfection was granted in 1969 in Canada (Conference on Irradiation, Laval, Que. 1984). Wheat irradiation prevents insect eggs, larvae and pupae from developing (Vanderstoep, 1986), but may also cause nutritional damage. Vitamins damaged by irradiation include vitamin A, B1, B2, B3, B6, B12, folic acid, vitamin C, E, and K. Essential polyunsaturated fatty acids are also affected (Webb et al.,1987). Although wheat, white flour, and whole wheat flour are treated with lower-energy ionizing radiations from Cobalt-60, there is still a possibility that some compounds within the food become radioactive, although the radioactivity rapidly decays (Josephson & Peterson, 1983). Toxic chemicals called radiolytes may also form, which may cause health problems over the long term. Some adverse effects have been found related to these, but there is still much scientific uncertainty (Josephson & Peterson, 1983). Irradiation technology is a serious health hazard and environmental hazard, especially if accidents occur where it is used.
STUDIES OF THE HEALTH EFFECTS OF BREAD
Since bread and wheat products are such an important part of daily food consumption, it follows that such food items be healthy and wholesome. Today's milling, refining, bleaching, enriching, and addition of various chemicals to flour and baked breads cause many scientists and medical workers to question their nutritional quality as well as their safety. There is little information on what bleaching and maturing agents do to the flour other than meet bakers' criteria, and toxicology tests may not realistically assess the dangers, since chemicals are tested separately. The general public, has become conditioned to commercial bread products, and is uninformed about the effects of the processing that flour undergoes. Many recorded cases demonstrate the effects of the quality of flour on the health of people or animals, and illustrate the importance of the nutritional value of bread to physical health.
Refined flour has been found less effective in promoting the growth of weanling rats than wholemeal, if the flour was the main source of protein (Chick, 1958).
Steel roller mills were introduced in Britain in 1872. By 1876, the birth rate began to decline from 36/1000 to less than 14/1000 in 1941, at which time the National Loaf became compulsory (85% extraction, including the germ). In the next two years, the birth rate rose to 16/1000. Vitamin E deficiency was the suspected cause, since it was believed to have something to do with human and animal reproduction, and is destroyed in the refining of flour. Friend Sykes was said to get his horses and cows to breed by feeding them wheat germ for two months, and Dr. L. J. Picton did the same with his stallions (Day, 1966).
Documented in 1936, was the diversity in physique of the different tribes of India, showing the effects of foods on health (McCarrison, 1936). The northern races were much stronger, due to wheat being the staple of their diet. They consumed chapattis cakes made from fresh coarse whole wheat flour. Experiments with albino rats determined the value of some of the Indian diets, and these results conformed with their effects observed on men. About 1 000 rats were fed a diet equivalent to the northern Indians' for a period equivalent to 50 human years. None were ill or died, or even delivered dead offspring. Deficiently-fed rats under the same conditions developed many ailments. Overall, 30% of the rats fed white flour died while only 4% of those fed whole wheat died. It was concluded that adequate nourishment could be found in a diet of whole cereal grains, milk products, legumes, fruits and vegetables, and eggs and meat occasionally.
Rats on the healthy northern diet were also compared to rats fed a diet equivalent to that of the poorer classes of England (McCarrison, 1936). This diet, deficient in vitamins and minerals, consisted of white bread, margarine, very sweet tea with a little milk, boiled cabbage and potato, cheap tinned meat, and jam. These rats had stunted growth, were badly proportioned, had dull coats, were nervous, bit attendants, and by the 60th day, began killing and eating the weaker ones. Post-mortem examinations revealed a high incidence of lung and gastrointestinal diseases. McCarrison believed that vitamin deficiency was responsible for the many health problems.
Dr. Estelle Hawley, of Rochester University, fed a group of rats McCay-Cornell bread made with unbleached flour, wheat germ, and soybean flour and a lot of milk solids. She fed another group commercial enriched white bread. Both groups also received an amount of margarine equivalent to 10% of the weight of the bread (Rorty, 1954). The first group lived healthy, but the second group became ill, produced stunted offspring and were extinct by the fourth generation.
A journal article, written in 1942, discusses the deterioration of the physique of the British, between the 18th century and the Boer War around 1900 (Alvarez, 1942). The most probable explanation was that they had come to depend too much on white flour and sugar, whereas their ancestors had eaten plenty of 'whole wheat flour.
In Denmark, during World War II, due to a food crisis, many domestic animals were slaughtered and their grain rations fed to humans. Consumption of white bread was stopped, and replaced by a bread made from a wholemeal of 67% rye, 21% oats, and 12% bran, called Kleiebrot. Consequently, the death rate fell to the lowest level ever registered in Europe. There were significant declines in the incidence of high blood pressure, heart disease, kidney problems, diabetes, and cancer, and there were no cases of digestive troubles (Marine & Van Allen, 1972; Day, 1966).
In 1970, Dr. Roger Williams, of the University of Texas's Clayton Research Foundation, recorded the effects, on 64 weanling rats, of being fed bread made from enriched flour (Passwater, 1975). Forty were dead within ninety days, and the rest had stunted growth, whereas similar rats fed whole-grain bread were normal; only three were not well.
A fear exists, among medical professionals, that emulsifiers, some of which are added to bread, may promote the absorption of otherwise non-absorbed substances, some of which may be carcinogenic. Emulsifiers include monoglycerides, diglycerides, and poly compounds which usually go by variations of the words 'stearate' and 'sorb' (ea. stearyl, polysorbate). Although glycerides are naturally produced by the body, this does not prove that their artificial use is safe. Some emulsifiers have been found to increase vitamin A absorption tremendously. This may be dangerous if the rest of an individual's diet supplies a large amount of vitamin A. Dr. Anton Carlson expresses the view that many have by stating, n...Small amounts of injury in certain percentages of the people may go undiscovered for generations. This is a serious problem involved in the changes of such a fundamental thing as the type of food for mans (Marine & Van Allen, 1972).
Enriched flour may have a lower vitamin bioavailability, since synthetic vitamins have been found to act different',y. For instance, they react differently to light, and synthetic vitamin C does not cure scurvy in mice as quickly as natural vitamin C (Day, 1966). Enriched flour products have also been found to lose more vitamins due to heat than do non-enriched products, because added vitamins are less heat-resistant. This is believed to be due to the absence of naturally occurring stabilizers (Mender, 1983; Thomas, 1990).
Many people claim to control allergic symptoms by eliminating bleached wheat products from their diets (Marine & Van Allen, 1972).
These are only a few examples to illustrate the nutritional inadequacy of refined flour products.
BENEFITS OF WHEAT FIBER
As a result of the refining of flour and changes in dietary habits, the consumption of dietary fiber has decreased by at least one half during the past two centuries. Epidemiological studies relate low fiber intake to many disease states, particularly those of the gastrointestinal tract (Birdsall, 1985). From his observations, Dr. Dennis Burkitt claimed that the large amount of plant fibers consumed by African natives protected them from suffering from many diseases common to Western man such as cardiovascular disease, colon cancer, diverticulae, appendicitis, hemorrhoids and varicose veins of the legs (Burkitt, 1972).
Diets high in complex carbohydrates such as whole cereal grains, legumes, and Units and vegetables are usually the custom in populations with very low incidence of cardiovascular disease (Brown et al.,1985). Studies indicate that high-fiber diets decrease blood pressure in normal as well as in hypertensive subjects (Birdsall, 1985). For elevated blood serum lipids, dietary recommendations include increasing carbohydrate consumption to make up 65% of total daily calories, emphasizing complex carbohydrates from nature', sources (Gotto et al.,1984), because they influence the absorption of fat-soluble substances from the digestive tract, and the reabsorption of bile acids and neutral steroils (Hodges et al.,1985). These recommendations are given to diabetics as well, since cardiovascular disease is their most likely cause of death (Anderson et al., 1990)
A diet rich in complex carbohydrates also improves glucose metabolism in diabetic subjects, by increasing their sensitivity to insulin, therefore resulting in reduced dosages requirements (Birdsall, 1985). In a study, Finnish wholemeal rye bread (100% wholemeal rye flour) was found to induce slower postprandial blood glucose responses in insulin-dependent diabetics than did mixed wholemeal bread (50% wholemeal rye flour & 50% white wheat flour) and white bread (100% white wheat flour). Grained wholemeal rye (35% of the wholemeal rye flour was replaced by whole rye grains) resulted in a blood glucose response similar to that after consumption of wholemeal rye bread. In non- insulin-dependent diabetics, the differences were not statistically significant, but wholemeal rye bread produced the lowest blood glucose response. The results believed to be due to the higher content of bran or non- digestible or non-absorbable carbohydrate in wholemeal flour, or grain (Heinonen et al., 1985). Perhaps wheat fiber's effect of reducing starch digestibility was also involved (Anderson, 1985: Leeds, 1985).
Numerous studies demonstrate that populations with the highest fiber intake have the lowest incidence of colon cancer. There is, however, also a correlation with total fat intake (Birdsall, 1985). A diet consisting of a low-fat, whole grain staple food, such as whole grain bread, would provide protective effects against colon cancer. Because bran reduced the number of tumors induced by chemical carcinogens in animal models (Bingham, 1990), it was concluded that it protects humans from colon cancer. A hypothesis for this effect is that fiber decreases intestinal contact with carcinogens.
For the Western population, constipation is a major problem. It may lead to hemorroids, diverticulae, and even contribute to the development of varicose veins (Burkitt, 1982). Wheat bran decreases intestinal transit time (Payler et al. 1975), because it decreases intestinal pressure, and increases peristalsis (Thomas, 1976). It is one of the best fecal bulking agents identified (Cummings et al., 1982), and is even more effective in raw form, because of the structural changes that occur in the latter, increasing the amount of bacterial degradation it undergoes in the intestine (Pomeranz, vol. 2, 1988). Wheat fiber is also claimed to strengthen, by stimulation, the intestinal mucosa, and decrease the incidence of gastroenteritis, or inflammation of the stomach or intestine (Thomas, 1976).
The phytates in wheat bran and germ bind minerals and have been believed to drastically reduce the bioavailability of minerals. Drastic reduction is not the case, and many factors, including what other foods are consumed at the same time, improve bioavailability. For example, consumption of meat, sufficient protein, and vitamin C increase the absorption of iron, for example (Pomeranz, 1988). Since whole wheat contains many more nutrients, a somewhat decreased bioavailability would be far from the detrimental effects of excluding bran altogether. Consumption of whole wheat flour has been shown to result in a greater absorption of iron than if low extraction flour was consumed (Burk et al., 1985). Studies also showed that, although the percent of zinc absorbed from white bread was twice that from whole wheat bread, since whole wheat bread supplied greater than three times more, the absolute quantity absorbed was more from whole wheat bread (Sanderstorm et al., 1980). Calcium is an exception, and phytates are said to have a drastic effect upon its absorption (Pomeranz, 1988). Smaller particles of fiber would be expected to lead to a greater bioavailability of the nutrients in the bran (Pomeranz, 1980), although smaller particles may not be as effective stimulating the bulking effects and the speeding up of intestinal transit (Wheaton, 1990). A certain degree of adaptation to phylates may occur as well, as observed in an experiment where, on the first five days of a fifteen day period, the absorption of some minerals was lower, with untreated as well as dephytinized wheat bran (Morris and Ellis, 1982; Morris et al., 1984).
Wheat fiber helps to neutralize acid secreted by the stomach, and is therefore of therapeutic value for persons with ulcers (Thomas, 1976).
Wheat fiber-rich foods are less energy-dense than low-fiber foods, and produce a feeling of fullness or satiety more quickly. The insoluble fiber in wheat bran slows digestion by decreasing the surface area of starch and other ingredients exposed to hydrolytic enzymes, slows absorption in the small intestine (Schneeman, 1982), and increases fecal excretion of fat and nitrogen (Anderson, 1985; Leeds, 1985). It may increase fecal energy loss by 60 to more than 300 kca/day via fat and protein loss (Vahouny, 1985). Wheat fiber-rich foods can therefore be beneficial in the treatment or prevention of obesity (Thomas, 1976).
The importance of wheat fiber cannot be overlooked. Pomeranz (1988) writes, n Thus the additional nutrients present in whole wheat products and the physiological effect of the fiber on fecal bulk and transit time suggest that Western industrialized populations would continue to benefit from the consumption of more whole wheat foods."
