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Where do the daily consumption recommendations come from? When does it make sense to take more than the 100% NRV amount? What are the maximum permitted amounts? When should I take which dietary supplement? What do IU mean for vitamins and how can this be converted into mg or mcg?
We try to answer all these questions in the following blog post.
Publisher and validity of reference values
There are a number of committees that make dosage recommendations for each micronutrient. The fact that the recommendations vary by a factor of 4 to 100 (!) depending on the committee shows very clearly that there is apparently no one, fixed guideline value.
Below you will find the committees relevant for the DACH region and internationally that deal with the setting of reference values:
• German Nutrition Society (DGE)
(Recommendations for nutrient intake; first published in 1956)
• Austrian Society for Nutrition (ÖGE)
• Swiss Society for Nutrition Research (SGE)
• Swiss Nutrition Association (SVE)
• Food and Nutrition Board (USA)
(Recommended Dietary Allowances RDA; first published in 1943)
• Food and Agriculture Organization (FAO) of the WHO
(Handbook on Human Nutritional Requirements)
• European Food Safety Authority (EFSA); since 2003
--> Recommendations vary by a factor of 4-100 depending on the committee!
Examples of reference values for middle-aged women:
(Source: https://www.dge.de/wissenschaft/referenzwerte/tool/)
When determining reference values, these bodies set certain premises. The reference values (for example for the DGE) only apply to:
- Average requirement (according to estimates, surveys, studies)
- of healthy people
- with an average lifestyle
- without any special stress
- Prevention of shortages as a target
- Not valid for
- people with stress
- sick
- Without taking variables into account
- Individual needs (no Gaussian normal distribution)
- Needs according to age, gender, physical performance
- Increased need (e.g. everyday stress, illness)
- Reduced intake
The DGE explains the “average lifestyle” with regard to nutrition as follows:
- “5x daily fruit and vegetables, including 3 portions with 375 g vegetables and 2 portions with 250-300 g fruit – preferably fresh!”
- “For people at risk, a targeted intake of food supplements can be useful, e.g. smokers, pregnant women, those on a reduction diet, the elderly, those with gastrointestinal diseases.”
(Source: Annette Braun, press spokeswoman of the DGE in ÄZ 19.7.1999)
It is already clear that the reference values determined in this way can hardly be universally valid. For example, who is free from stress, environmental toxins, everyday drugs, etc.? Who is completely "healthy"? And we don't even have to think about serious illnesses here - even an absorption disorder in the intestine ensures that only a fraction of the nutrients actually reach the cells.Often undetected “silent inflammation” (chronic inflammation), e.g. due to autoimmune diseases, also leads to an increased need for micronutrients.
The undisputedly increased need for older people, athletes, etc. is also ignored. In addition, a normal/healthy, balanced diet is assumed, which is often not possible for most people in their everyday lives.
It must also be emphasized that the goal when setting reference values is always to avoid deficiency symptoms, i.e. the purely preventive idea. It is therefore clear that, logically speaking, the therapeutic use of micronutrients or the replenishment of low nutrient depots must always be accompanied by a dosage above the specified reference values.
// All official recommendations for daily nutrient intake refer to healthy normal people without risks and with full micronutrient stores! //
BfR – Maximum Level Recommendations (2018)
In addition to the recommended reference values, which are set individually by each committee based on the premises outlined above and which follow the preventive idea of maintaining health, there are also committees that deal with setting maximum amounts for micronutrients. In Germany, this is the Federal Institute for Risk Assessment (BfR), which derives the maximum values based on 3 parameters:
- Tolerable Maximum Daily Intake [UL]
- intake through the usual diet
- Intake reference values (recommended amounts for daily intake)
The safe intake level for food supplements (including fortified foods) is derived as follows:
- Tolerable maximum daily intake (UL) minus nutrient intake from the usual diet (reference value) = Safe intake
- This means: If the reference value is not reached through diet, the dietary supplement dose may be higher, possibly up to the maximum daily intake (UL)!
BfR maximum level recommendations
(As of March 16th)2021)
|
| dietary supplements | Food & Beverages |
| vitamin A | 0.2 mg | 1 mg |
| vitamin B3 | 160 mg | 47 mg |
| vitamin B6 | 3.5 mg | 1.08 mg |
| vitamin B12 | 25 mcg | 7.6 mcg |
| folic acid | 200 (400) mcg | - |
| vitamin C | 250 mg | 76 mg |
| vitamin D | 20 mcg (800 IU) | - |
| vitamin E | 30 mg | 9 mg |
| Vitamin K1 + K2 | 80 + 25 mcg | - |
| Vitamin B1, B2, pantothenic acid, biotin | No limit | No limit |
| chrome | 60 mcg | 19 mcg |
| fluoride | - | - |
| iron | 6 mg | - |
| iodine | 100 (150) mcg | Salt 2500 mcg/100 g |
| copper | 1 mg | - |
| manganese | 0.5 mg | - |
| molybdenum | 80 mcg | 24 mcg |
| selenium | 45 mcg | - |
| zinc | 6.5 mg | - |
| calcium | 500 mg | 120 mg/100 ml |
| chloride | - | - |
| potassium | 500 mg | - |
| magnesium | 250 mg | 39 mg |
| sodium | - | - |
| phosphorus | - | - |
overdose risks
- vitamins à Dosage usually rather high and broad
- Water-soluble vitamins (B, C): dRno risk of overdose, as increased amounts are easily excreted via the kidneys/urine
- Fat-soluble vitamins (A, D, E, K): Hypervitaminosis risk in
- A (25000 – 83000 IU)
- β-carotene (smokers < 15 mg)
(with a very one-sided diet & high intake via supplements) - D (only at high levels of approx. 150 ng/ml and higher)
- Vit. B3 (only with high intake of 1-2 g/day)
- minerals & trace elements à Dosage rather cautious (narrow therapeutic range)
- In high quantities: All toxic
- Moderate risk: calcium, magnesium, iodine (factor UR/RAD = 5-100)
- Increased risk: iron, phosphorus, zinc, selenium (factor UL/RDA < 5)
- Fundamentally toxic: e.g. mercury, cadmium
As with the determination of the reference values, there are also significant deviations from country to country in the maximum quantities – and it turns out that Germany is generally far below the values of its European neighbours. (Source: https://www.verbraucherzentrale.nrw/sites/default/files/2021-04/Hoechstmengen_Europa_April%202021.pdf):
The following graphic shows the recommended intake and the maximum amount (UL). The principle applies that a dosage with the recommended intake (these are the "100% NRV" on the product labels of food supplements) serves to maintain health, i.e. prevent disease, in healthy people without special stress and with full micronutrient stores.
Above the recommended "100% NRV" amount, the area of prevention begins, provided that the nutrient stores are not completely full and/or there are special stresses. If the dosage is further increased up to the defined maximum amount (UL), the therapeutic application area then comes - ie the use of micronutrients for (accompanying) therapy of an already manifested disease.
This means that in practice the dosage must be individualised according to…
- area of application (primary, secondary prevention, therapy, aftercare)
- indication (e.g. severity of the disease)
- Mono- or combination administration (combination reduces single dose)
- substance group (e.g. for water-soluble vitamins rather large, for fat-soluble vitamins rather small dosage range)
- Age, gender, situation (e.g. pregnancy)
- Recommendations (studies, literature, DGE etc.)
- laboratory values (levels of substances and markers)
- Low normal load (eg prevention): Low normal substance levels usually sufficient
- High exposure, high risks, advanced or severe disease: Usually higher substance levels required
- Low initial levels of a substance: Usually high (possiblyparenteral) dosage
“Rule of thumb” for dosing orthomolecular substances from practice
- prevention of deficiency symptoms
- usual 1-fold recommendations of the RDA / DGE
- preventive focus
- usual up to 3 times the recommendations of the RDA / DGE
- Example intake recommendations for vitamin C “to prevent disease”:
- for adults: Daily intake 100 mg according to DGE
- For primates in captivity: Daily intake 55 mg vitamin C / kg body weight (!) à i.e. for a person weighing 70 kg, this would be 3850 mg per day (!)
- Therapeutic use & targeted supplements
- High doses of individual substances
Consideration of bioavailability variables
- Ultimately, it is not the dose administered that counts, but what actually reaches the body!
- Fundamentally different bioavailability of individual substances
- Different bioavailability and compound form of individual preparations
- Time of intake (e.g. interactions, fatty foods)
- Individually different digestive and absorption capacity
- Functionality of metabolism and intestines (digestion, absorption)
- Consequence:
- Dosage according to blood level (no fixed dosages)
- Consequence for prevention and for preventive studies (!)
- at high blood levels no positive effects with increased intake
- with low blood levels, low bioavailability and
Functional disorders (e.g. intestinal) higher dosages necessary
General recommendations for the timing of taking important micronutrients
- vitamins
- Divide water-soluble vitamins into several doses, especially at higher doses (give before meals)
- Give fat-soluble vitamins as one dose (with meals) / Attention: Benfotiamine (vitamin B1) is fat-soluble!
- Add combinations of water- and fat-soluble vitamins to meals
- minerals and trace elements
- Especially at higher doses, a distinction must be made between zinc, iron, copper, calcium,
manganese, magnesium and fluorine preparations as well as between these substances and
chelating agents (e.g. α-lipoic acid) Interval of about 2 hours and possibly distribution over several doses recommended
- Especially at higher doses, a distinction must be made between zinc, iron, copper, calcium,
| Recommendation | substance examples |
| Before meal | B vitamins, vitamin C |
| During or immediately after a meal (e.g. due to stomach acid) | Calcium (possibly in the evening), magnesium, |
| During or immediately after meals (especiallydue to fat solubility) | Vitamin A, D, E, K, carotenoids, |
| Fasting or independent of meal (due to possible absorption restriction by | Potassium, Chromium, |
| Between meals | proteases |
Biological activities of vitamin forms: Conversion of IU / mg or mcg
| vitamin | underlying asset | Corresponding biological activity |
| vitamin A | 1 mg vitamin A | 1 mg retinol (definition) = “retinol equivalent” |
| vitamin D | 1 mg cholecalciferol / D3 | 40 million IU of vitamin D |
| vitamin E | 1 mg vitamin E | 1 mg RRR-α-Tocopherol (definition) = d-α-Toc. |
| vitamin | underlying asset | Corresponding biological activity contained in |
| vitamin B1 | 1 mg B1 (thiamine) | 1.32 mg Thiamine Hydrochloride DAB |
| vitamin B2 | 1 mg B2 (riboflavin) | 1.42 mg riboflavin 5'-phosphate Na dihydrate DAB |
| vitamin B6 | 1 mg B6 (pyridoxine) | 1.22 mg Pyridoxine Hydrochloride DAB |
| pantothenic acid | 1 mg pantothenic acid | 1.11 mg calcium D-pantothenate DAB |
| vitamin C | 1 mg vitamin C | 1 mg ascorbic acid DAB |