Minerals Part X: Silicon, arsenic and lead
At the end of the section on minerals, the variety of unknown and also negatively affected substances becomes clear once again. In the context of some elements, excessive consumption of these should be avoided in order to escape impending toxic side effects. But some of the unknown substances show interesting and quite promising functions for our body again and again.
To round off the mineral substances, we will once again turn our attention to the “foreign” and threatening-sounding elements silicon, arsenic and lead.
You already have enough on your plate, but you don’t want to miss the most important facts? Here a summary:
- Silicon occurs naturally as silicon oxide and silica. Food also contains silicon, although silicon data for food are considered unreliable.
- The body absorbs 20 to 50 milligrams of silicon daily. Modified silicon compounds in particular are dangerous, but should be taken into account in occupational medicine.
- Silicon is probably important for bone development and connective tissue metabolism. Nevertheless, it remains controversial as an essential substance
- Arsenic is deposited especially in hair, nails and skin, which is why this material can be used as an indicator of arsenic poisoning
- Arsenic is particularly at home in lakes, rivers and seas, which is why marine animals in particular are considered to be rich in arsenic.
- There are no known biochemical and physiological processes in which arsenic is important. However, there are approaches according to which arsenic is important for the synthesis of specific metabolites and plays a role in certain enzymatic reactions. However, the essential importance remains controversial.
- Specific arsenic compounds, such as arsenic trioxide, are particularly dangerous. According to the WHO, no more than 3.5 milligrams of arsenic should be consumed daily.
- Like calcium, lead is built into the bones and then released again over a period of years. This process can lead to poisoning. According to the WHO, the upper limit for daily intake is 0.5 milligrams of lead. There are numerous symptoms of poisoning
- Animal studies indicate that lead deficiency can have a negative effect on growth, skin and special membrane proteins. Nevertheless, lead remains controversial in its importance for our bodies
Modifications of silicon can be dangerous
The element silicon is found in nature mainly as silicon oxide and silicic acid. Silicon is also present in food, although information about the individual silicon content in food is often unreliable. We consume about 20 to 50 milligrams of the substance daily, although the absorption of silicon via the intestines is considered to be extremely poor. However, silicon oxide, which is often used in industry, plays a special role within occupational medicine. The reason for this is that modifications of the substance, such as quartz, are classified as carcinogenic. Experience has shown that inhaling these substances increases the risk of bronchial carcinoma.
Important functions of silicon
When it comes to the benefits of silicon for our body, one comes across the development of bones and connective tissue. Currently, it is assumed that silicon has an important function for bone development and the proper metabolic processes of connective tissue. This is particularly evident in the property of various forms of silicon that tend to form networks. Nevertheless, it remains hypothesis and conjecture, so that an essential intake is not recommended at the moment. Deficiency symptoms are not known so far.
Arsenic mainly in marine animals
If we first look at the amount of arsenic found in the body, we see a relatively low figure of 0.005–0.1 milligrams per kilogram of dry matter. However, there are parts of the body in which arsenic is proportionally more abundant. These include above all hair, nails and skin, which are not infrequently used as indicators of arsenic overload. The trace element is found above all in lakes, seas, rivers, soils and in animal and plant foods. On average, about 80 micrograms of arsenic are consumed daily in this country; in marine regions such as Japan, the figure is considerably higher at 300 micrograms. The reason for this is the different dietary habits, because sources such as fish and seafood are considered to be particularly rich in arsenic.
Essential property of arsenic questionable
The function of arsenic in our body is particularly interesting. Although a hypothetical daily requirement of about 12 to 25 micrograms was calculated after considering several animal experiments and studies, no physiological and biochemical processes are currently known in which arsenic would be of great importance. Nevertheless, there are approaches that do not consider influences on the synthesis of metabolites or enzymatic reactions to be out of the question. Negative consequences in the presence of arsenic deficiency, such as increased calcium excretion or growth disorders, have also been observed in animal experiments.
Caution with increased arsenic intake
On the one hand, there are some harmless compounds containing arsenic; on the other hand, compounds such as arsenic trioxide can be lethal above certain levels. It is not for nothing that the odourless powder was used as a murder tool in the past. The WHO generally recommends consuming no more than 3.5 milligrams a day. However, it only becomes lethal from about 70 milligrams. Intoxication with arsenic mainly manifests itself with gastrointestinal complaints.
Parallels between lead and calcium
Lead, like its two group-mates, is also an extremely controversial mineral. The element lead can be incorporated into the bones just like calcium. In the course of bone metabolism, the stored lead is released back into the blood over a period of years and can lead to intoxication. Meaningful and lasting effects for our body can so far only be derived from animal experiments. But even these findings are manageable, with effects on growth, skin and special membrane proteins.
Caution also with lead
The WHO recommends 0.5 milligrams as the upper limit for the daily amount of lead. Lead is absorbed through food and the air we breathe. The toxic effect mainly refers to the adverse effect on various enzymes. Acute intoxication with lead results in, among other things, a lead fringe of the gum line, encephalopathy, colic and anaemia. Chronic intoxications manifest themselves with loss of appetite, a pale complexion and headaches.
Text sources:
(1) Biesalski et al, Pocket Atlas of Nutrition, 8th edition, 2020.
(2) Lüllmann et al., Pharmacology and Toxicology, 18th edition, 2016
(3) Elmadfa and Leitzmann, Human Nutrition, 6th edition, 2019.
(4) Rassow et al, Dual Series — Biochemistry, 4th edition, 2016.
(5) Ebermann and Elmadfa, Textbook — Food Chemistry and Nutrition, 2nd edition, 2011.
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