The body's defense does not sit in a single organ

First the fast response, then the precise one

Anyone speaking of defense means not a single organ but a system of cells, solutions, and messenger substances distributed across the whole body. Part of it circulates in the blood, part sits in lymph nodes and spleen, another part waits in skin, intestinal wall, and airways. The technical literature divides this system according to the speed of its response into two areas that are closely interlocked.

Both areas are replenished from the same source: from stem cells of the bone marrow, which daily produce new white blood cells in large numbers. Where cells arise in this quantity, cell division, protein building, and metabolic turnover run without interruption — and with them the enzymatic processes in which trace elements have a documented function.

Phagocytes recognize patterns, not particulars

Granulocytes and macrophages react within minutes. They do not distinguish between individual pathogen strains but respond to structures that recur in many microorganisms: particular sugar chains, building blocks of the bacterial cell wall, unmistakable sections of foreign genetic material. If such a structure fits one of their receptors, the cell flows around the object and encloses it in a vesicle inside the cell.

These cells are short-lived. According to current estimates a neutrophil granulocyte spends only hours to a few days in the blood before it is replaced. Resupply is therefore not a special case but continuous operation.

Lymphocytes lay down a memory

The second area works more slowly and in return with precision. T and B lymphocytes each carry a receptor that fits a single marker. If this marker arrives, the cell in question divides many times over and forms descendants with the same recognition structure. Part of them persists for years. On this store rests the fact that a second encounter with the same marker runs differently from the first.

The maturation of these cells takes place not in the bone marrow but in the thymus gland behind the breastbone. The organ reaches its greatest extent in childhood and is increasingly replaced by fatty tissue in adulthood, without giving up its task entirely.

What reactive compounds arise during pathogen defense

Once a phagocyte has enclosed an object, it switches on an enzyme in the pinched-off vesicle that deliberately generates oxygen radicals. These compounds are chemically aggressive — that is their purpose. Because the same molecules could also attack the body's own structures, every cell has enzyme systems that convert such compounds back into inconspicuous products. Several of these enzymes carry a metal or semimetal atom in their active center.

At this point the European list carries two separate entries. Selenium contributes to the protection of cells from oxidative stress — Pursuant to Regulation (EU) No 432/2012. For zinc there is a separate, independent entry with the same wording: Zinc contributes to the protection of cells from oxidative stress — Pursuant to Regulation (EU) No 432/2012. The two statements were assessed individually and apply individually; they cannot be combined into a joint claim about both elements.

Origin: farmland soil, seawater, menu

Both elements reach the organism through food, but by very different routes. Selenium ultimately comes from the rock from which a soil formed. Plants take up what is available there; animals take it over from their feed. Central European soils carry on average less selenium than the soils of large parts of North America, which is why the same grain variety can carry very different values depending on the growing area.

Zinc is distributed more evenly across soils but accumulates in return in particular tissues. Meat, cheese, eggs, and shellfish therefore stand at the top of the tables, fruit and most vegetable varieties at the bottom. Whole grain cereals also carry considerable amounts, though together with phytate from the outer layers, which binds part of it in the intestine.

Selenium follows the soil, zinc follows the protein

This rule of thumb explains a large part of the figures in the nutrition tables. It has two remarkable exceptions. The first is the Brazil nut: its tree draws selenium up from deep soil layers, which is why individual nuts carry values far above anything else that ends up on a plate. The second is sea salt. Seawater carries both elements in traces, but salt is consumed in gram amounts, not in hundred-gram portions — for the daily balance the contribution is correspondingly small.

What cannot be derived from these figures

Content tables describe foods, not people. From them neither an individual intake amount nor a statement about the condition of a single person can be derived. The four quoted claims apply to the general population without a medical diagnosis and describe normal bodily functions. They say nothing about diseases, about their course, or about the effect of a particular product. Anyone needing an assessment of their own diet should discuss it in a medical practice.