O 'empty'of minerals' gluten-free breads

Groundbreaking study evaluates food composition; researcher proposes flour fortification.

O 'empty'of minerals' gluten-free breads

Groundbreaking study evaluates food composition; researcher proposes flour fortification.

Our daily bread has, in recent years, acquired new forms, flavors, appearances, and compositions, among which is the "gluten-free" option, which is increasingly winning over consumers. For people with celiac disease (affected by an autoimmune disease related to gluten consumption), intolerances, allergies, or any type of dietary restriction, variety is very welcome. But the benefit of the absence of gluten in bread does not guarantee a more nutritious product in terms of minerals, points out research developed at the Faculty of Food Engineering (FEA) of Unicamp by chemist Paulo Henrique Leuteviler Pereira.

In addition to identifying low levels of essential minerals such as iron (Fe), calcium (Ca), zinc (Zn), and magnesium (Mg) in gluten-free breads, the groundbreaking study simulating human digestion revealed low bioavailability (the portion of the nutrient released from food after digestion) of these minerals. Bearing in mind the maxim that "we are not only what we eat, but what we absorb," the researcher also developed a proposal in his thesis for fortifying breads to increase the concentration and bioavailability of iron.

Pereira knows firsthand the difficulty of giving up bread in daily life. Ten years ago, his wife was diagnosed with celiac disease, and since then, gluten has become an undesirable ingredient in the family. “It has always been very difficult to find gluten-free foods, especially bread, but the products available have improved in recent years, in appearance and taste. In the beginning, the breads were very crumbly. Today there are more and better options,” he rejoices.

According to the researcher, consumers of gluten-free products have the right to know that they are ingesting less iron and therefore have a "deficiency" in minerals when compared to traditional products containing gluten. "Celiac patients, in general, already have a nutritional deficiency, according to the literature in the field. It would be important for them to have the same mineral content in gluten-free bread as in traditional bread."

After analyzing 44 different samples of gluten-free bread and four traditional wheat breads (for comparison), Pereira found a very large variation in the amount of calcium in the breads, from 9 mg to 200 mg per 100 g. In many samples of gluten-free bread, the amount of iron was so small that it was not detectable. The same pattern was repeated with zinc: up to 2,09 mg in wheat bread, compared to a maximum of 0,99 mg in gluten-free bread.

Legislation

Basically, one of the main reasons why gluten-containing breads have higher levels of essential minerals is that, in Brazil, wheat flour is mandatorily fortified with iron and folic acid, as mandated by a public health policy to combat anemia. Iron fortification is a nutritional strategy recommended by the World Health Organization (WHO), since iron deficiency anemia is the biggest global public health problem, a disease that affects the immune and cognitive systems.

Gluten-free breads, which use different flours such as rice flour and potato starch, among others, do not have specific legislation regarding permitted formulations. Therefore, those who consume gluten-free bread "lose" the opportunity to ingest the same amount of iron as people who consume traditional fortified breads. Based on the results of the analyses, Pereira felt motivated to develop, during his research, a way to fortify gluten-free bread.

Fortification of rice flour with ferrous sulfate (a form of iron permitted for the fortification of wheat and corn flours in Brazil), for bread processing, was effective in increasing the concentration and bioavailability of the mineral. The researcher tested the addition of ferrous sulfate in its free form and in microencapsulated form. In both cases, the gluten-free fortified bread had a significant amount of iron, contributing 7% of the so-called Recommended Daily Intake (RDI) of this mineral for adults (considering a 50 g serving).

'We are what we absorb'

“Contrary to what is often said, we are not what we eat, but what we absorb,” says Pereira. According to FEA professor Juliana Azevedo Lima Pallone, supervisor of the thesis, one point is the quantity of minerals in the bread, another point is the quantity of minerals in the food that remains available in our digestive tract so that our body can later absorb and use them, she explains, referring to bioaccessibility. “This shows the complexity of the subject and demonstrates that it is not enough to know the quantity of minerals,” says Pallone.

To assess the bioaccessible fraction of essential minerals that can be absorbed by the body, which implies being soluble at the end of digestion, Pereira used a laboratory digestion model (in vitro) that simulates what happens in the stomach and intestines during digestion. “The in vitro experiment simulates all phases of human digestion, from chewing, then the stomach and intestines, to see the soluble fraction. What remains soluble is what was released from the food and can be absorbed,” explains Pallone.

Bioavailability is influenced by food composition. Phytates and fiber, which may be present in flours and other ingredients used in the processing of traditional and gluten-free breads, are antinutritional factors, for example, that bind to minerals, preventing their release and hindering absorption. "Soy extract is an example of an ingredient used in various formulations that may contain antinutrients." The risk also exists in traditional breads fortified with iron. That is, even the iron added to wheat bread may not be absorbed. The absorption of minerals in baked goods is a general challenge for all types of bread.

Contamination

The thesis also investigated inorganic contaminants in the breads studied. Tests did not identify the presence of arsenic (As), cadmium (Cd), or lead (Pb), classified as toxic and cumulative inorganic contaminants in the body, therefore posing a risk to human health, with neurological, carcinogenic, and renal effects. All bread samples analyzed showed low levels of inorganic contaminants.

Sodium

Regarding sodium, all breads – both gluten-free and gluten-containing – showed high levels, ranging from 118,1 mg to 500,9 mg per 100 g. Generally, sodium is added in the form of salts to improve flavor and texture. The gluten-free breads evaluated were within the maximum limits, while among the traditional sliced ​​breads, 25% of the samples exceeded the maximum limit of 400 mg of sodium/100 g. Another important finding is that several samples evaluated showed sodium levels different from those presented on the labels. Sodium is the only mineral that is listed as mandatory for food labeling and has positive effects on the body, provided it is consumed in small quantities.

Pereira worked in the industry for six years and today is a scientific researcher at the Adolfo Lutz Institute in Campinas, in the food sector. "This work could provide an insight for the industry, which could then invest in fortifying gluten-free bread with minerals," suggests Pallone.