Nickel in Food
Nickel (Ni) is an iron -like metal that can be introduced into the body through food .
Nickel is a very widespread element in the environment as it represents:
- a fundamental constituent of many metal alloys (steel)
- a volatile element, therefore inhalable with pulmonary ventilation
- polluted groundwater, soil, etc.
Ultimately, nickel represents an almost ubiquitous microelement which is distinguished by the different sources of origin and the high probability of contact with living organisms.
Biological role of nickel
Nickel is a metal that boasts a well-defined biological importance, therefore, its introduction with food is fundamental; this DOES NOT MEAN that it is important to take as much nickel as possible – small quantities (traces) are sufficient and no PHYSIOLOGICAL deficiency forms are known (instead present in hepatic impairment) – but simply that this metal also contributes to the maintenance of metabolic homeostasis .
The nickel contained in foods is absorbed in the intestine ; the quantity introduced daily is in the order of a few micrograms, but its presence in foods can reach hundreds of milligrams, especially in fruit and vegetables obtained from the cultivation of polluted land.
The primary source of elimination of nickel introduced with food is represented by urine and feces , while the homeostatic regulation of its blood concentration is attributable to renal function .
The biological function of nickel is essentially involved in:
- Hormone metabolism
- Maintenance of the integrity of cell membranes
- Enzymatic constitution (arginase, trypsin, carboxylase etc.)
- Glucoseand lipid metabolism
- Stabilization of nucleic acids
Foods that contain nickel
Nickel is contained in foods in two forms:
- Biological constituent
- Polluting
The foods belonging to the first group and which naturally contain nickel are above all: cocoa , some crustaceans , almost all lamellibranch/bivalve molluscs , whole grains and whole grains (especially oats and buckwheat ), legumes, seeds ( walnuts and hazelnuts ) and cauliflower .
The foods belonging to the second group and which contain polluting nickel are above all: fats – hydrogenated oils and all refined and industrially processed foods. This happens because the nickel contained in kitchen equipment and utensils can be released into foods due to a reaction to the acidic environment or by mechanical friction. Furthermore, as anticipated, it is possible to identify more or less important traces of contaminating nickel, especially in fruit and vegetable foods obtained from agriculture on polluted land (rain containing nickel from smog, aquifers containing nickel, soil rich in nickel, etc.).
- Foods very rich in nickel: cocoa and derivatives, whole grains , walnuts and hazelnuts , ALL legumes
- Nickel-rich foods: packaged foods, bay leaves , herring , asparagus , lobsters , bananas , broccoli , cinnamon , carrots , cauliflower, whole grain cereals , cucumbers , cloves , chicory , cherries , onions , liver , Dutch cheese, berries sea , pasteurized cow’s milk , yeast , melons , nutmeg , vegetable oils , pepper , celery , spinach , wine
- Foods low in nickel: sorrel and similar, garlic , citrus fruits , apricots , beer , coffee , scallops and similar, beef , pork , veal , lamb , cabbage , coca-cola , refined flours of corn , rye , wheat , shrimp, lettuce , margarine , apples , sunflower oil , potatoes , pears , fish (Gadidae family), pine nuts , radishes , pearl rice , plums , dairy products , eggs , grapes . NB . Water and table salt should NOT contain nickel.
Adverse reactions to nickel – nickel allergy
The adverse reaction that can occur upon contact with nickel is a cellular allergy and NOT a humoral one. This is a common disorder; in Germany it affects 6% of women and 12% of men, and seems to appear only after the 6th year of life.
Nickel allergy manifests itself above all with contact eczema but ONLY if the subject touches objects containing high quantities of nickel (costume jewellery, watch straps, belt buckles, etc.). In this regard, it has been noted that of all, only 25% of allergy sufferers react DERMATOLOGICALLY to the introduction of nickel in food.
Unfortunately, the diet of those allergic to nickel is highly restrictive and the reduction of their intake inevitably involves the elimination of: foods that are very important for human nutrition , all objects containing nickel and all culinary utensils containing nickel.
