This section brings together what can be quantified about this element: the chemistry of the ion in mineral and tissue, the ranges from two nutrient databases, the FDA’s Daily Value reference, and the three structure/function claims that are recognized for it in the United States.
In a mineralogical collection this element stands out before any instrument is brought to bear. It is found in a pink chain silicate that takes its name from that very hue, and it is found in a black oxide that served for centuries as an additive in glassworks. Both specimens contain the same element in different oxidation states — and neither has anything to do, at first glance, with what appears in a nutrition facts panel.
The color of a mineral depends on which portions of light the electrons of its incorporated metal ion absorb. In the chain silicate the ion sits in a divalent state among oxygen neighbors, allowing red and blue wavelengths to pass while green is retained; the eye perceives a pink. In the oxide the same element is present at a higher oxidation state, in a different coordination environment and with different interatomic distances — the specimen appears deep black.
For a long time this observation was the only practical way to engage with the element. In the recipe books of glass makers the black ore is listed as a remedy for the greenish tint that iron impurities leave in quartz sand. The addition was a craft technique and not a nutritional insight.
That a metal can assume several oxidation states is not a side note but the very reason it is employed in certain proteins. Reactions in which a single electron changes hands require a center that can accept that electron and release it shortly afterward. An ion with a fixed valence is unsuited for this; it takes on other tasks in proteins, such as holding a fold in shape.
In human tissue the element is virtually never found free. It is bound to transport proteins or to the binding pocket of an enzyme, and dedicated transport proteins handle the handoff when it moves between cellular compartments. Among the enzymes that carry such a center are the superoxide dismutase of the mitochondrial matrix, the arginase of the liver cell, pyruvate carboxylase, and several transferases that attach sugar residues to nuclear proteins.
Anyone who looks up figures for this element in reputable databases will rarely find a single value and almost always a range. This is not a shortcoming of the survey but a property of the subject: the content of a plant-based product depends on the composition of the soil it grew in, and that varies from region to region.
| Product | Range per 100 g | Note |
|---|---|---|
| Black tea leaves, dried | 30–60 mg | Dry product, not the brewed infusion |
| Hazelnuts | 4–5 mg | Varies by origin and variety |
| Rolled oats | 3–4.5 mg | Whole-grain product |
| Whole wheat flour | 2.5–4 mg | Includes bran and germ |
| Brown rice | 1.1–2 mg | Unpolished |
| White wheat flour | 0.4–0.7 mg | Bran largely removed |
| Brewed black tea | 0.2–0.5 mg | Per 100 mL of beverage |
| Potatoes, cooked | 0.10–0.20 mg | Preparation shifts the value |
| Lean beef | 0.01–0.03 mg | Animal-based product |
Excerpt from two nutrient databases, rounded ranges. The columns quantify the content of a product; no efficacy claim can be derived from them.
Of the amount on the plate, only a small fraction reaches the bloodstream; the scientific literature cites single-digit percentages. Phytate from grains and legumes, along with other divalent ions, compete for the same absorption pathway. What is absorbed is largely excreted again by the liver — the primary route out leads through bile, not through the kidneys.
This yields a reading aid for any table of this kind: an analytical value describes the food, not the person who eats it. No row in such a listing can tell you how well any individual is supplied, and none of them constitutes a recommendation.
Besides the milligram figure, a Supplement Facts panel carries a percentage. Its reference amount — the Daily Value (DV) — is set by the FDA in 21 CFR 101.9; for manganese it is 2.3 milligrams. The number makes labels comparable to one another. It is not a requirement figure for any individual person.
Separately, the National Academies of Sciences (formerly the Institute of Medicine) have published an Adequate Intake (AI) estimate for adults that largely aligns with the Daily Value. Both figures are valid because they answer different questions: one belongs to labeling law, the other to a scientific assessment. They do not compete, and one does not replace the other.
A structure/function claim does not appear on a label without prerequisites. Under the Dietary Supplement Health and Education Act (DSHEA), the manufacturer must have substantiation that the claim is truthful and not misleading. The product must also carry the required FDA disclaimer and the amount of the nutrient must be declared on the Supplement Facts panel.
There is also a procedural requirement: the manufacturer must notify the FDA within 30 days of first marketing a product bearing a structure/function claim. The claim must describe the role of a nutrient in affecting the structure or function of the body; it may not claim to diagnose, treat, cure, or prevent any disease.
In publications the Adequate Intake figure is occasionally cited as though it were part of the claim’s wording. It is not. The recognized structure/function claims reproduced below mention no quantity at all — neither a daily amount, nor an upper limit, nor a timeframe. Anyone who places a number next to one of these statements is citing two different documents.
The following three statements reflect the recognized structure/function claims for manganese as permitted under DSHEA. Each addresses a distinct physiological role. Any text outside the quoted statements was written by the Rhodonitkamm editorial team and carries no regulatory authorization.
Structure/function claim under DSHEA — 21 U.S.C. § 343(r)(6)
Structure/function claim under DSHEA — 21 U.S.C. § 343(r)(6)
Structure/function claim under DSHEA — 21 U.S.C. § 343(r)(6)
| Subject of the Claim | Condition of Use | Legal Basis |
|---|---|---|
| Protection of cells from oxidative stress | Truthful, not misleading; substantiation on file; FDA disclaimer required | DSHEA, 21 U.S.C. § 343(r)(6) |
| Maintenance of normal bones | Truthful, not misleading; substantiation on file; FDA disclaimer required | DSHEA, 21 U.S.C. § 343(r)(6) |
| Normal connective tissue formation | Truthful, not misleading; substantiation on file; FDA disclaimer required | DSHEA, 21 U.S.C. § 343(r)(6) |
Overview of the three recognized claims. The condition column paraphrases the requirements; the statutory text governs.
What the three claims do not contain is just as telling as what they say. None of them names a disease, a symptom, an age group, a sex, or a dosage form. And none of them can be combined with another into a joint statement, even when two sentences share the same phrasing.
Only very roughly. The hue is caused by the incorporated ion, but its intensity also depends on the crystal structure, on trace impurities, and on the thickness of the specimen. Two pieces of the same mineral can look quite different in color intensity and yet carry similar concentrations. A content figure is determined in the laboratory, not by looking at a hand specimen.
It is the same chemical element, but not the same compound and not the same context. The glass makers’ additive was an oxide in a high oxidation state that performed an optical function in the melt. In food and in tissue the element is present in a different binding form. Nothing about nutrition follows from the historical use.
No. Mentioning an enzyme is a description from the scientific literature and not a recognized claim. For the labeling of a product, only the wording that is substantiated under DSHEA counts. Anyone who derives a custom formulation from it steps outside the permissible scope, even if the statement is scientifically accurate.
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The expert section on this page is an abridged version. The paid edition features a table with fourteen products, the manganese-dependent enzymes are listed with their citations in the standard literature, and labeling law and claim regulations are covered in separate chapters. The file is a DRM-free PDF; no user account is required.
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