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Where do the daily intake recommendations come from? When does it make sense to consume more than the 100% NRV amount? What are the maximum permissible amounts? When should I take which dietary supplement? What do they mean? I.E. for vitamins and how can this be converted into mg or mcg?
We will try to answer all these questions in the following blog post.
Publisher and validity of reference values
There are numerous committees that issue dosage recommendations for each micronutrient. The fact that the recommendations vary by a factor of 4 to 100 (!) depending on the committee clearly shows that there is apparently no single, fixed guideline.
The following are the relevant bodies for the DACH region and internationally that deal with the setting of reference values:
• German Nutrition Society (DGE)
(Nutrient intake recommendations; 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 setting reference values, these bodies establish certain premises. The reference values (for example, those of the DGE) apply only to:
- Average requirement (according to estimates, surveys, studies)
- of healthy people
- with an average lifestyle
- without any special stress
- Avoiding 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 demand (z.B. everyday stress, illness)
- Reduced intake
The DGE explains the “average lifestyle” with regard to nutrition as follows:
- “5x fruit and vegetables a day, including 3 portions of 375g vegetables and 2 portions of 250-300g fruit – preferably fresh!”
- “For people at risk, a targeted intake of dietary supplements can be useful, z.B. for smokers, pregnant women, those on a weight-loss diet, the elderly, and those with gastrointestinal diseases.”
(Source: Annette Braun, press spokesperson of the DGE in ÄZ 19.7.1999)
It's 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 consider serious illnesses here – even a malabsorption disorder in the intestines ensures that only a fraction of the nutrients actually reaches the cells. Even often undetected "silent inflammation" (chronic inflammation), e.g.,due to autoimmune diseases, for example, lead to an increased need for micronutrients.
The undisputedly increased need for older people, athletes, etc. is also ignored. Furthermore, it assumes a normal/healthy, balanced diet, which is often impossible for most people to achieve in their daily lives.
It must also be emphasized that the objective when setting reference values is always to avoid deficiency symptoms. D.h. the purely preventative idea. It thus becomes clear that, logically speaking, the therapeutic use of micronutrients or the replenishment of depleted nutrient stores must always be accompanied by a dosage above the established reference values.
// All official recommendations for daily nutrient intake refer to healthy, normal individuals without risk factors and with full micronutrient stores! //
BfR – Maximum Level Recommendations (2018)
In addition to the recommended reference values, which are determined individually by each body based on the premises outlined above and which follow the preventive principle of maintaining health, there are also bodies that are responsible for setting maximum intake levels for micronutrients. In Germany, this is the Federal Institute for Risk Assessment (BfR), which derives the maximum intake levels based on three parameters:
- Tolerable maximum daily intake [UL]
- Intake levels through the usual diet
- Reference intake 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) less nutrient intake from the usual diet (reference value) = safe intake
- D.h.: 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 16th2021)
|
| 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): d.R.no risk of overdose, as increased amounts are simply excreted via the kidneys/urine
- Fat-soluble vitamins (A, D, E, K): Hypervitaminosis risk in
- A (25,000 – 83,000 IU)
- β-carotene (smokers < 15 mg)
(with a very one-sided diet & high intake via supplements) - D (only at high levels of approximately 150 ng/ml and higher)
- Vit. B3 (only with high intake of 1-2 g/day)
- Minerals & trace elements à Dosage rather cautiously (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)
- Basically toxic: z.B. 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 i.d.R. is 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 intake (UL). The principle applies that a dosage with the recommended intake (these are the “100% NRV” on the product labels of food supplements) is good for maintaining health, d.h. Prevention, in healthy people without particular stress and with filled micronutrient stores.
Above the recommended "100% NRV" amount, the prevention range begins, provided nutrient stores are not fully filled and/or special stresses are present. With further dosage increases up to the defined maximum level (UL), the therapeutic range of application is reached – d.h. the use of micronutrients for the (accompanying) therapy of an already manifested disease.
D.h. in practice, dosage must be adjusted individually according to ….
- Area of application (primary and secondary prevention, therapy, aftercare)
- Indication (z.B. severity of the disease)
- Mono- or combination administration (combination reduces single dose)
- Substance group (z.B. for water-soluble vitamins, the dosage range is rather large, for fat-soluble vitamins, the dosage range is rather narrow)
- Age, gender, situation (z.B. Pregnancy)
- Recommendations (studies, literature, DGE etc.)
- Laboratory values (levels of substances and markers)
- Low normal load (z.B. Prevention): Low normal substance levels usually sufficient
- High exposure, high risks, advanced or severe disease: Usually higher drug levels required
- Low initial levels of a substance: Usually high (possiblyparenteral) dosage
“Rule of thumb” for the dosage of 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 70 kg person 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 supply (z.B. Interactions, fatty foods)
- Individually different digestion and absorption capacity
- Functionality of metabolism and intestines (digestion, absorption)
- Consequence:
- Dosage according to blood level (no fixed dosages)
- Consequences for prevention and preventive studies (!)
- at high blood levels no positive effects with increased intake
- with low blood levels, low bioavailability and
Functional disorders (z.B. intestine) higher dosages are necessary
General recommendations for the timing of intake of important micronutrients
- Vitamins
- Divide water-soluble vitamins into several doses, especially for higher doses (give before meals)
- Give fat-soluble vitamins as 1 dose (with meals)/Caution: 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 (z.B. α-lipoic acid) Interval of approximately 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 (z.B. due to stomach acid) | Calcium (possibly in the evening), magnesium, |
| During or immediately after a meal (v.a.due to fat solubility) | Vitamins 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 value | Corresponding biological activity |
| Vitamin A | 1 mg vitamin A | 1 mg retinol (definition) = “retinol equivalent” |
| Vitamin D | 1 mg cholecalciferol/D3 | 40 million IU vitamin D |
| Vitamin E | 1 mg vitamin E | 1 mg RRR-α-Tocopherol (definition) = d-α-Toc. |
| vitamin | Underlying value | 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 |