**1. Introduction**

Exposure to toxins in the environment, soil and air increase the effects on the health of the population in all ages and physiological states of higher priority such as childhood and pregnancy [1]. The role of the microbiota has been extensively studied with effects on health maintenance, but this is only possible with a diet that promotes its development, growth and maintenance of key bacteria [2]. An adequate diet (complete, varied, balanced, sufficient and safe) generates intestinal health by preserving the microbiota [3]. Among the key nutrients, it is known that soluble fibers function as a prebiotic for bacteria. The fructoligosaccharides represents one kind of these soluble fibers and are found in food such as banana, bean, onion, garlic, etc., that are part of the traditional Mexican diet [4]. After several descriptive studies in the state of Guanajuato, since 2004, first with arsenic in drinking water in population of several communities, in 2015, it is achieved through an intervention study with a supplementation of several vitamins and minerals in population adolescent, a greater urinary arsenic and fluoride excretion, as well as a greater consumption of traditional foods such as beans, bananas, orange and quelites [5–7]. The traditional Mexican diet composed for quelites, legumes (beans, lentils), a wide variety of fruits and vegetables are rich in flavonoids, vitamins (A, B, C, D, E) have been associated prebiotic effect and a greater

excretion of metals. Monroy-Torres, et al found more excretion for fluoride and arsenic in adolescents who maintained these foods in their diet during the study [7]. Knowing the food transition and its impact on the changes in the microbiota is part of a research subline of Environmental Nutrition and Food Security [8].

The contamination of the main environmental resources, necessary to preserve the life of any human being are water, soil and air, which have a deterioration in quantity and quality integrating the presence of various pollutants with their corresponding health risks. Current evidence has integrated and recognized the main toxins present in water, soil, air and therefore in food, with important implications for the health of people at different stages of life, are lead, cadmium, mercury and arsenic [9, 10].

Lead, for many years, is part of the compounds of gasoline and to date is still used in pottery despite the existence of a rule that prohibits it for Mexico and in many countries. Low doses begin to generate problems especially in childhood and when there is anemia or poor nutrition, its toxicity is exacerbated. Sweets have been a source of lead exposure and also some lead-based paints. Pregnant women and children are more susceptible to lead exposure due to their high bioavailability at the gastrointestinal level and its permeability of the blood-brain barrier [11].

Cadmium compounds not only are present in batteries and cigarette smoke, but also food could represent a source of exposure to this metal. Cadmium is used in the manufacture of rechargeable batteries (composition based on nickel and cadmium) whose main problem is that everything containing cadmium is reusable or recyclable being household waste one of the most frequent routes of exposure, so that its exposure has increased and ascending during the twentieth century. One concern is the low dose of this metal to generate kidney damage, bone damage and fractures, although this also varies according to the population group [10, 11].

With respect to mercury, this metal mainly causes deterioration and neurological damage and the main source of exposure of people is the consumption of fish contaminated with methylmercury, as well as dental amalgams that in rural communities remain the main option, given their durability. Due to the exposure of mercury orally through the consumption of fish, food alerts have been generated to avoid or minimize its exposure in pregnant women mainly, since the nervous system develops throughout fetal life, so it is vital to alert the population and avoid the consumption of large fish such as tuna, shark and swordfish [9, 12].

Arsenic is a metalloid present at different concentration in water tables. The toxicity of arsenic depends of its valence states and its organic or inorganic form. Organic As is considered less toxic than inorganic, as it is easier to excrete, this can be found mainly in shellfish and some cereals. Inorganic As is most toxic in its trivalent form that can chemically combine with sulfhydryl groups, these functional groups form intermolecular and intramolecular bridges in proteins and their structure and biological function depend accordingly [1, 12].

El To address in this chapter, with utmost importance, we consider a summary of these four toxic heavy metals since little is known about their interactions and role of the microbiota, in the chemical reactions of oxide-reduction or those that apply for their detoxification of the organism. The health effects will depend on the toxic route of entry, dose and exposure time, as well as the nutritional status of each person. One of the main causes of contamination of food by these metals is that the land and water in which they are contaminated with these environmental toxins and this coupled with the fact that they can also be contaminated in processes of their subsequent industrialization and apart from this. The process generates foods with poor null nutrient content (fiber, vitamins and minerals) and also have more additives and preservatives [9, 10]. Reason for achieving a correct diet that is

**151**

for example.

conclusive [16].

*Role of the Microbiome as the First Metal Detoxification Mechanism*

is difficult to achieve in the toxicological aspect [1].

some vitamins and is also involved in the absorption of ions [13, 14].

complete, varied, balanced, sufficient, adequate and safe, has become a challenge, especially safety, defined "that the usual consumption of a diet or food does not involve health risks because it is free of pathogenic microorganisms, toxins and contaminants and is consumed in moderation" [3], whose definition we can affirm

Recently, the study of intestinal microbiota has increased significantly, because important protective and metabolic functions have been associated. On this regards, intestinal microbiota competes for nutrients, space and receptors with pathogenic microorganisms, as well as stimulating the production of antimicrobial peptides and immunoglobulins. The microbiota converts many complex substances such as starches, cellulose, pectin and gums into metabolites that are easily absorbed by the host, it also ferments another non-digestible residues from the diet, synthesizes

There are several probiotic bacteria that have been administered gastrointestinally to sequester toxins present in food, such as a 250 g yogurt with *1010 CFU* of *Lactobacillus rhamnosus* supplemented with probiotics to reduce exposure to metals in pregnant women and children with elevated blood lead levels in a study conducted in Tanzania, changes in blood metal levels were evaluated and children's gut microbiomes were analyzed, finding a protective effect against additional increases in mercury (3.2 nmol/L; P 0.035) and arsenic (2.3 nmol/L; P 0.011), only in women, but not in children [1, 2]. One of the reasons for these differences can be explained by the physiological immaturity of children as well as the stage of growth that are most vulnerable them; In the case of women where benefit was observed, it is explained why it is known that women have an efficiency in the excretion of metals, unlike men [1, 2, 15]. On the other hand, as regards Cadmium, it has been observed in women in the menopause stage, differences in metal metabolism and excretion as well as greater absorption of cadmium orally in women with anemia and osteoporis, causing kidney damage, osteoporosis and osteomalacia [15]. As women, in the menopause period should be more monitored being that is when there is a deterioration in nutritional status such as anemia exacerbating increased exposure to lead,

Respect of lifestyle change, nutrition plays an important role in maintain the microbiota; poor quality diets are rich in refined grains and added sugars, salt, unhealthy fats and foods of animal origin; and low in whole grains, fruits, vegetables, legumes, fish and nuts are the main causes of poor microbiome. Processed red meats are associated with an increase in cardiovascular diseases and strokes. However, for our population, the relationship between these variables was not

Gut microbiota is composed of bacteria, fungi, archaea, viruses and protozoa. Some of the functions of gut microbiota are metabolism and the development of the nervous system and immune system [17]. Furthermore, alterations in microbiota, a process known as dysbiosis, have been associated with the development of obesity and diseases such as diabetes, inflammatory bowel disease and even neoplasms such as colon cancer. Some factors that cause intestinal dysbiosis are antibiotics, alcohol consumption, infection of pathogenic microorganisms and diet [18], this last one can favor the proliferation of specific phyla of bacteria in the gut [19]. Likewise, gut dysbiosis has been associated to exposure to heavy metals as cadmium and mercury [20, 21], halogenated compounds such as fluoride and metalloids such as arsenic, these last two contaminants of water for human consumption [22]. On the other hand, the role of the microbiota in the detoxification of xenobiotics [23], arsenic [24] and heavy metals [25], has been little studied. In the case of heavy metals, it has been observed that probiotics, especially lactic acid bacteria (LAB),

*DOI: http://dx.doi.org/10.5772/intechopen.89232*

#### *Role of the Microbiome as the First Metal Detoxification Mechanism DOI: http://dx.doi.org/10.5772/intechopen.89232*

*Prebiotics and Probiotics - Potential Benefits in Nutrition and Health*

arsenic [9, 10].

excretion of metals. Monroy-Torres, et al found more excretion for fluoride and arsenic in adolescents who maintained these foods in their diet during the study [7]. Knowing the food transition and its impact on the changes in the microbiota is part

The contamination of the main environmental resources, necessary to preserve the life of any human being are water, soil and air, which have a deterioration in quantity and quality integrating the presence of various pollutants with their corresponding health risks. Current evidence has integrated and recognized the main toxins present in water, soil, air and therefore in food, with important implications for the health of people at different stages of life, are lead, cadmium, mercury and

Lead, for many years, is part of the compounds of gasoline and to date is still used in pottery despite the existence of a rule that prohibits it for Mexico and in many countries. Low doses begin to generate problems especially in childhood and when there is anemia or poor nutrition, its toxicity is exacerbated. Sweets have been a source of lead exposure and also some lead-based paints. Pregnant women and children are more susceptible to lead exposure due to their high bioavailability at the gastrointestinal level and its permeability of the blood-brain barrier [11].

Cadmium compounds not only are present in batteries and cigarette smoke, but also food could represent a source of exposure to this metal. Cadmium is used in the manufacture of rechargeable batteries (composition based on nickel and cadmium) whose main problem is that everything containing cadmium is reusable or recyclable being household waste one of the most frequent routes of exposure, so that its exposure has increased and ascending during the twentieth century. One concern is the low dose of this metal to generate kidney damage, bone damage and fractures,

With respect to mercury, this metal mainly causes deterioration and neurological damage and the main source of exposure of people is the consumption of fish contaminated with methylmercury, as well as dental amalgams that in rural communities remain the main option, given their durability. Due to the exposure of mercury orally through the consumption of fish, food alerts have been generated to avoid or minimize its exposure in pregnant women mainly, since the nervous system develops throughout fetal life, so it is vital to alert the population and avoid

Arsenic is a metalloid present at different concentration in water tables. The toxicity of arsenic depends of its valence states and its organic or inorganic form. Organic As is considered less toxic than inorganic, as it is easier to excrete, this can be found mainly in shellfish and some cereals. Inorganic As is most toxic in its trivalent form that can chemically combine with sulfhydryl groups, these functional groups form intermolecular and intramolecular bridges in proteins and their

El To address in this chapter, with utmost importance, we consider a summary of these four toxic heavy metals since little is known about their interactions and role of the microbiota, in the chemical reactions of oxide-reduction or those that apply for their detoxification of the organism. The health effects will depend on the toxic route of entry, dose and exposure time, as well as the nutritional status of each person. One of the main causes of contamination of food by these metals is that the land and water in which they are contaminated with these environmental toxins and this coupled with the fact that they can also be contaminated in processes of their subsequent industrialization and apart from this. The process generates foods with poor null nutrient content (fiber, vitamins and minerals) and also have more additives and preservatives [9, 10]. Reason for achieving a correct diet that is

although this also varies according to the population group [10, 11].

the consumption of large fish such as tuna, shark and swordfish [9, 12].

structure and biological function depend accordingly [1, 12].

of a research subline of Environmental Nutrition and Food Security [8].

**150**

complete, varied, balanced, sufficient, adequate and safe, has become a challenge, especially safety, defined "that the usual consumption of a diet or food does not involve health risks because it is free of pathogenic microorganisms, toxins and contaminants and is consumed in moderation" [3], whose definition we can affirm is difficult to achieve in the toxicological aspect [1].

Recently, the study of intestinal microbiota has increased significantly, because important protective and metabolic functions have been associated. On this regards, intestinal microbiota competes for nutrients, space and receptors with pathogenic microorganisms, as well as stimulating the production of antimicrobial peptides and immunoglobulins. The microbiota converts many complex substances such as starches, cellulose, pectin and gums into metabolites that are easily absorbed by the host, it also ferments another non-digestible residues from the diet, synthesizes some vitamins and is also involved in the absorption of ions [13, 14].

There are several probiotic bacteria that have been administered gastrointestinally to sequester toxins present in food, such as a 250 g yogurt with *1010 CFU* of *Lactobacillus rhamnosus* supplemented with probiotics to reduce exposure to metals in pregnant women and children with elevated blood lead levels in a study conducted in Tanzania, changes in blood metal levels were evaluated and children's gut microbiomes were analyzed, finding a protective effect against additional increases in mercury (3.2 nmol/L; P 0.035) and arsenic (2.3 nmol/L; P 0.011), only in women, but not in children [1, 2]. One of the reasons for these differences can be explained by the physiological immaturity of children as well as the stage of growth that are most vulnerable them; In the case of women where benefit was observed, it is explained why it is known that women have an efficiency in the excretion of metals, unlike men [1, 2, 15]. On the other hand, as regards Cadmium, it has been observed in women in the menopause stage, differences in metal metabolism and excretion as well as greater absorption of cadmium orally in women with anemia and osteoporis, causing kidney damage, osteoporosis and osteomalacia [15]. As women, in the menopause period should be more monitored being that is when there is a deterioration in nutritional status such as anemia exacerbating increased exposure to lead, for example.

Respect of lifestyle change, nutrition plays an important role in maintain the microbiota; poor quality diets are rich in refined grains and added sugars, salt, unhealthy fats and foods of animal origin; and low in whole grains, fruits, vegetables, legumes, fish and nuts are the main causes of poor microbiome. Processed red meats are associated with an increase in cardiovascular diseases and strokes. However, for our population, the relationship between these variables was not conclusive [16].

Gut microbiota is composed of bacteria, fungi, archaea, viruses and protozoa. Some of the functions of gut microbiota are metabolism and the development of the nervous system and immune system [17]. Furthermore, alterations in microbiota, a process known as dysbiosis, have been associated with the development of obesity and diseases such as diabetes, inflammatory bowel disease and even neoplasms such as colon cancer. Some factors that cause intestinal dysbiosis are antibiotics, alcohol consumption, infection of pathogenic microorganisms and diet [18], this last one can favor the proliferation of specific phyla of bacteria in the gut [19]. Likewise, gut dysbiosis has been associated to exposure to heavy metals as cadmium and mercury [20, 21], halogenated compounds such as fluoride and metalloids such as arsenic, these last two contaminants of water for human consumption [22]. On the other hand, the role of the microbiota in the detoxification of xenobiotics [23], arsenic [24] and heavy metals [25], has been little studied. In the case of heavy metals, it has been observed that probiotics, especially lactic acid bacteria (LAB),

could contribute to their elimination, because these kinds of bacteria have a high affinity for heavy metals [26]. Therefore, a diet that favors the proliferation of LAB could be used as the natural detoxification of the organism in populations exposed to environmental pollutants. In this chapter, we review the role of diet in the gut microbiota and its possible use for the natural detoxification of the organism.
