Dietary Supplement Categories: Legal Framework, Vitamins & Minerals

By Giannis Moutafidis, Founder & CEO, Swiss Formula · Last updated: June 2026 · ~14 min read

This free guide examines the main categories of dietary supplements — trace elements, vitamins, minerals, amino acids, biotics (probiotics/prebiotics/postbiotics), botanicals and specialty supplements — with an emphasis on their safe use. This is not a marketing or sales strategy guide (you'll find that in The Ultimate Guide to Building Your Own Brand) — it's a technical map of the product itself: what it contains, how it works, and where caution is needed, written for professionals who formulate, manufacture or recommend supplements.

What Is Defined as a Dietary Supplement & Legal Framework

Before diving into individual categories, we need a clear starting point: what a dietary supplement actually is, both legally and in substance.

A dietary supplement is a food intended to supplement — not replace — the normal diet. It is a concentrated source of nutrients (vitamins, minerals) or other substances with a nutritional or physiological effect (amino acids, botanical extracts, biotics, and others), available in dosage form: capsules, tablets, powders, vials.

In the European Union, supplements are legally classified as foods, not medicines. This means two things at once: on one hand, market entry is faster and less costly than for a medicine; on the other hand, precisely because they don't go through the strictness of pharmaceutical licensing, the responsibility for safe use is shared among everyone in the chain — the manufacturer, the person responsible for market placement, and ultimately the professional who recommends them.

Distinction from Medicines & from "Foods for Special Dietary Use"

A dietary supplement is not intended to prevent, treat or cure disease — this is the line that legally separates it from a medicine, regardless of how "potent" its ingredient is. It also differs from "foods for special dietary use" (e.g. products for athletes, calorie-reduced diets, specific medical purposes), which are subject to a different regulatory framework.

Labeling Requirements & Permitted Claims

Labeling is not an aesthetic matter — it's the point where legislation meets the everyday act of selling. However strict it may seem, there's one simple rule behind all of it: the consumer must be able to know exactly what they're buying, and must not be misled into thinking they're buying something that cures.

What Must Be Mandatorily Stated

• The main nutrients that characterize the product, using their category name
• The recommended daily dose
• A warning not to exceed the recommended daily dose
• A statement that the product is not a substitute for a balanced diet
• Exact quantities of active substances, and the percentage contribution to the Recommended Daily Allowance (RDA) where applicable
• A reminder to keep out of reach of children

What Is Explicitly Prohibited

• Claims of preventing, treating or curing disease — only medicines are permitted to use these
• Unauthorized health claims — only those included in the official EU Register of Health Claims are permitted
• Claims that undermine proper nutrition — e.g. that a supplement is "the only way" to achieve something

Vitamins: Fat-Soluble & Water-Soluble

The first and most important distinction among vitamins is not by letter, but by solubility type — because this directly determines the safety risk from excessive intake.

Fat-soluble vitamins (A, D, E, K) are absorbed with the help of fats and stored in fat tissue and the liver. This means they don't need daily replenishment, but it also means that any excess is not easily excreted — systematically excessive intake can lead to accumulation and toxicity, with vitamin A and D being the best-known examples of clinically significant overdose.

Water-soluble vitamins (C, B-complex) dissolve in water, are not stored to any significant degree, and any excess is excreted through urine. This makes them generally safer at higher doses, but they require more frequent or daily intake — and deficiencies appear relatively more easily when diet is insufficient.

Tolerable Upper Intake Levels (UL): Why They Matter

For every vitamin and mineral, the scientific community (via EFSA at EU level) has established a Tolerable Upper Intake Level (UL) — the maximum daily amount from all sources (food + supplements) that is not expected to cause adverse effects in the general population. This is critical for anyone designing a formula: dosage is not a matter of "the more, the better."

Indicative values based on EFSA guidelines; exact limits vary by age group and must be verified against the current official source before finalizing a formula.

Bioavailability Forms: Not All Forms Are Equal

A detail that's often overlooked: the same vitamin can exist in more than one chemical form, with significantly different bioavailability. The best-known example is vitamin B12: cyanocobalamin is the most common and stable form in supplements, while methylcobalamin is the active form used directly by the body, without requiring conversion in the liver — which has practical relevance for individuals with specific metabolic characteristics.

Minerals & Trace Elements

The second major categorization concerns minerals, which are divided into two subcategories based on the amount the body needs:

• Macrominerals — required in larger amounts: calcium, magnesium, potassium, sodium, phosphorus
• Trace elements — required in much smaller (trace) amounts, but their role is equally critical: zinc, selenium, iodine, chromium, copper, manganese, molybdenum

The fact that a trace element is needed in a small amount doesn't mean its importance is small — on the contrary, precisely because the safety margin is narrower, correct dosing becomes more critical. Iodine, for example, is needed in an amount smaller than 1mg/day, but both its deficiency and excessive intake can disrupt thyroid function.

Chelated Forms vs Inorganic Salts

As with vitamins, a mineral's chemical form directly affects its bioavailability. Inorganic salts (e.g. ferrous sulfate, magnesium oxide) are more economical but generally less well absorbed, and more often associated with gastrointestinal discomfort. Chelated forms (e.g. iron bisglycinate, magnesium citrate) are "bound" to amino acids or organic acids, which improves absorption and reduces side effects — at a correspondingly higher cost.

Interactions Between Minerals

A point often overlooked in formula composition: minerals don't act in isolation — they compete with each other for the same absorption mechanisms in the gut. The most important interactions:

• Zinc – Copper: long-term intake of high zinc doses can cause secondary copper deficiency
• Calcium – Iron: calcium reduces iron absorption when taken together
• Calcium – Magnesium: they compete for the same absorption transporters at high doses

Summary & Next Steps

In this section we covered the legal framework governing all dietary supplements, labeling requirements, and examined in depth the first two major categories: vitamins and minerals/trace elements, with an emphasis on safety points — tolerable upper limits, bioavailability forms, and interactions.

In the next section we move on to amino acids, fatty acids, and the probiotics – prebiotics – postbiotics triad (metabiotics) — a rapidly evolving category that deserves special attention.