Is it wise to prefer white bread to whole wheat bread?

Bread was baked before the invention of agriculture, and potentially even contributed to that invention. It is located at the base of our food pyramid. It constitutes the mainstay of the Mediterranean diet. It represents the most important food in the diet of Sardinian centenarians.

But are we sure that the bread we eat now is the same food? How much has bread changed with the advent of refined flour? Is it wise to prefer white bread to whole wheat bread?

Bread consists of flour and water, which the fermenting microorganisms use as a food substrate. It is a food that is at the same time simple and complex, one of those miracles of science in the kitchen where the ear of wheat is transformed into a fragrant loaf. It is the emblem of culture on nature; the preparation of the soil, the cultivation of the cereal, the milling in flour, its leavening by billions of living organisms, and finally the complex cooking process with the typical phenomena of browning and caramelization, which release that unmistakable mix of aromas and fragrances. However, in this simple recipe, there is the possibility of obtaining a healthful product or a bad one – very bad, like bread made from excessively refined flours. Actually, the practice of refining grains is considered by many to be one of the great plagues of the 19th and 20th centuries, due to the devastating consequences on the health of consumers.

The wheat caryopsis consists essentially of four different structures:

  • A protective wooden shell (husk).
  • The outer bran layers, where one finds non-glutinous proteins, most of the grain’s soluble and insoluble fiber, B vitamins, mineral salts and other phytochemicals.
  • A lipid germ, which contains essential fatty acids omega 3 (alpha-linoleic) as well as antioxidants, such as vitamin E and beta-carotene, which are essential to protect those lipids from oxidation.
  • And finally an endosperm consisting mainly of starch, a complex carbohydrate formed by long glucose chains.

In the past, when grinding of grains could only take place with the help of stone mullers, it was not possible to remove any of these structures except for the husk. The resulting product contained of all the other caryopsis structures, and all their associated nutrients. With this type of bread, each bite brought, along with the carbohydrates contained in the endosperm, a rain of vitamins, antioxidants, proteins, essential fatty acids and dietary fiber.

In 1870, milling rollers of steel and porcelain were invented, and within a few years they became the standard. This grinding technique completely eliminates both the bran and the germ, leaving behind only the endosperm. This layer consists mainly of starch, composed of the monosaccharide sugar called glucose. The food industry discovered that removing the germ and bran was advantageous in terms of shelf life. The fats contained in the germ make the resulting flours less durable because they cause rancidity; a germ-free flour can be stored for a very long time without becoming rancid. It is a versatile and durable product that can be managed and transported according to market needs. The wooden layers of the bran also counteract the elastic properties of the glutinous network, at the expense of long leavening.

At the same time, within a few years after the discovery of refining techniques, nutritional deficiencies of group B vitamins and iron began to spread. Along with these came the spread of constipation and digestive problems, gluten intolerance, increased cardio-vascular diseases, diabetes and even some cancers (such as those of the prostate and colon). These chronic degenerative diseases were observed at high levels for the first time at the turn of the nineteenth and twentieth centuries in the colonies of western countries, after the introduction of refined flours and sugar. Previously, these diseases were virtually unknown in these countries, and therefore they came to be known as western diseases.

Surprisingly, doctors of the time had already observed that the increase in the incidence of some metabolic diseases was related to the introduction of new unbalanced dietary patterns. Reading the scientific literature of those years shows the appearance of various articles that sounded the alarm bell. Inevitably, however, industry won the day, and white bread became the norm despite the damage to the health of consumers. During the First World War, in Denmark in 1917, the refining of flour was prohibited for purely economic reasons. The removal of the outer layers of bran led to the loss of 23% of the caryopsis, because there were war-related food shortages at that time, the Danish government forbade the refining of grains. In response, the nutritional conditions of the population were surprisingly improved. The mortality rate decreased by 34% – despite the deaths in battle during the Great War – because deaths due to cardiovascular diseases, diabetes, and tumors decreased so dramatically. Similar responses were seen in Great Britain during the Second World War.

The phenomenon was so evident to the world health authorities that in 1947, the congress of the United States of America proclaimed the US Enrichment Act, which required the addition of a certain amount of nutrients to previously refined flour. After refining, it was compulsory by law to add iron, niacin, thiamine, and riboflavin (folic acid was added to this list in 1996). Unfortunately, these vitamins represent only a small proportion of all the substances that are irretrievably lost during the refining process. In 1950, the authoritative nutritionist Adelle Davis calculated that these flours were as enriched as you would be if you were given 99 cents after being robbed of 25 dollars!

Nutrient loss is well demonstrated by official data from the USDA (United States Department of Agriculture). With the refining process, 90% of thiamine, 80% of niacin, 60% of riboflavin, 80% of folic acid, 60% of vitamin B6, 70% of vitamin B5, and 100% of vitamin E are lost. It's not just the vitamins that pay the price; 60% of the calcium, 75% of the potassium, 75% of the iron, 80% of the magnesium, 60% of the zinc, 85% of the manganese, and 75% of the copper are also lost, along with 60% of the linoleic acid, the noble proteins of the bran, and 100% of the insoluble dietary fiber.

Lately, the market share of bread made with whole wheat flour has grown, due to the increasing demand from consumers. Unfortunately, in the vast majority of cases, so-called “whole grain” products are actually created by adding a handful of bran to refined flours. These foods are not even remotely equivalent to traditional whole wheat bread. A bread made without wheat germ has lost its most important nutritional properties. The addition of a handful of bran is not enough to compensate for the severe loss of nutrients during the refining process. Furthermore, there is excessive crushing of the insoluble fibers by industrial milling cylinders, which compromises their most important intestinal function – mechanical acceleration of intestinal transit time. The ideal solution is that of grinding with stone mullers, which do not overheat the flour and roughly break up the dietary fiber, and so they are able to perform their normal healthful function.

In summary, flour refining brings with it three distinct problems. The first is represented by the increase in the glycemic index. A piece of white bread made with double zero refined flour has a glycemic index of 96. This is equivalent to drinking a pure glucose solution in water. Although many people think of bread as being a healthy food, the truth is that white bread is just a way to convey sugar into the blood. Almost all refined flours are made up of starch, which is nothing but a complex sugar formed by long chains of glucose. Since the insoluble fiber is not present in refined flour, the amylases of the digestive tract have immediate access to the starch chains, freeing glucose molecules quickly for absorption into the bloodstream. The more refined the flours are, the more starch is accessible to the amylase enzymes that release glucose. The sharp rise in glucose causes an equally sharp increase in blood levels of insulin. These insulin spikes, with all of their secondary effects, are responsible for the onset of type two diabetes and metabolic syndromes.

The second problem with refined flour is that the lack of fibers and minerals make white bread more caloric than whole wheat. The total absence of insoluble fiber, and the resulting reduction in the ability to absorb water, makes the white bread denser from the caloric point of view. The third problem concerns the considerable loss of macro and micronutrients in white flours. Whole wheat bread is a complete, balanced, and nutritious food. Eating white bread is just a way to add unnecessary sugar to our diet. It is an unbalanced food that brings empty calories and nutritional imbalances.

To bake bread in a natural way, our ancestors prepared mother yeast. A certain amount of flour was mixed with water, and yeasts and environmental bacteria were then permitted to contaminate the substrate, which offers a source of sugar for microorganisms. With the acidification of the mixture, the environment becomes more and more selective, encouraging a specific typology of yeasts and lactobacilli. The compound thus obtained has a characteristic acidity with a pH between 4.2 and 4.7; in this range, the fermenting microorganisms that metabolize sugars and produce CO2 and organic acids proliferate. The sourdough (or “mother yeast”) thus obtained constantly needs to be nourished with the addition of new flour, which is mainly composed of sugars.

Microorganisms ferment glucose, of which starch is made, and the gaseous substances thus produced become trapped in the glutinous network. This protein structure has elasticity and a certain degree of extensibility. The increase in the volume of CO2 trapped in the cavities of the protein structure determines the increase in volume, causing leavening. The dozens of different species of yeasts and lactobacilli establish an environmental balance, which self-regulates the presence of particular species and produces a myriad of organic acids, volatile and aromatic substances that contribute to the unique fragrance and nutritional characteristics of naturally-leavened bread.

Making bread with sourdough is not an exact science. It is more an art than a craft process. Success depends on a series of interconnected and interdependent factors, such as the temperature of the air and the flour, the humidity level of both of these, the variety and the relative number of the fermenting species, the activation of the yeasts and their need for fermentation sugars, along with other factors. Unfortunately, the food industry does not like this degree of unpredictability. Rather, modern industry always tries to standardize and break down complex processes into repeatable (and therefore more manageable) operations, in order to be able to control and speed up the entire baking process. For this reason, there is an increasing preference for highly refined flours and instant yeast. Refined flours are almost exclusively made of sugar, which speeds up fermentation. Instant yeast (or brewer's yeast) is nothing but a single purified and standardized yeast crop, Saccharomyces cerevisiae, which makes the whole process predictable and repeatable.

Unfortunately for consumers, the product obtained cannot even remotely be compared to a product obtained with the traditional method. A bread that rises in an hour with a palate composed entirely of Saccharomyces cerevisiae is very different from a bread that rises in 8 hours with hundreds of different species of yeasts and lactobacilli. The differences are not exclusively in the aroma and taste, which will be much richer and more complex in the traditional bread, but also on a nutritional level. The main difference lies in the action carried out by the organic acids produced by the variety of microorganisms, which perform a myriad of important functions. These compounds activate wheat enzymes. Amylases begin to release simple sugars from starch, while proteases play their proteolytic role by disassembling protein structures and releasing single amino acids. These released sugars and amino acids will undergo caramelization and browning reactions during cooking, which will increase the complexity of the aromas and flavors. Moreover, the proteolytic activity makes the amino acids more available, and therefore increases the digestibility of the product.

We then observe an intense enzymatic activity that literally breaks down gliadin, one of the proteins constituting gluten (which are gliadin and glutenin). Professor Gobetti of the University of Bari published a study in 2004 showing that naturally leavened bread is much better tolerated by celiacs than is white bread. By virtue of this discovery, it has been hypothesized that the increasing prevalence of intolerances such as gluten sensitivity is actually due to the immoderate consumption of white bread obtained with instant leavening. Furthermore, organic acids, acting on the leavening process, slow down the absorption of sugars and consequently lower the glycemic index of the bread. It has been shown that bread, even if made with very fine and highly refined flour, has a lower glycemic index if fermented with mother yeast. In addition, these same organic acids activate phytases, enzymes that hydrolyse phytic acid during long rising and release those mineral salts that were blocked by phytates, thus making them bioavailable for intestinal absorption.

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