The study’s authors believe their methodology is scientifically robust enough to overcome ‘weaknesses’ in the approaches being considered by European authorities to harmonise EU-wide maximum vitamin and mineral doses in supplements.
Current permitted levels of micronutrients are based on the Population Reference Intakes (PRI, used by the EFSA (2010a)) or Nutrient Reference Value (NRV) (formerly referred to as the Recommended Daily Allowance or RDA).
Standards such as the RDA are used as starting points for methods that determine the relative risk of the micronutrient.
However, the authors argue these methods do not take into account the variability between micronutrient forms or risk-benefit associated with exceeding these levels among specific population groups.
The research, which was funded by the non-profit organisation Alliance for Natural Health International and by Solgar Vitamins, builds upon an approach detailed in a study that also attempted to define intake ranges based on deficiency risks (or lack of benefit) and toxicity.
The model also looked to extend the intake–incidence data to provide a range of estimates that could be considered.
Risk-benefit model
This latest study, conducted by scientists from the Netherlands Organisation for Applied Scientific Research (TNO), takes into account a wider range of relevant data available.
This data includes findings from human studies, bioavailability data showing variability between specific forms of micronutrients and, in the case of animal studies, data on species comparability.
The approach was then summarised into a series of steps that were flexible enough to make use of this broad data range and included:
- The identification of relevant (sub-)populations based on the intended use of the micronutrients and/or based on concerns or specific effects known for (vulnerable) sub-populations.
- The origin of effective dose for 50% of a population (ED50) (values for benefit and risk from key data for the relevant (sub-) populations.
- A severity of effect rating, upon which reasonable benefit and risk incidences can be derived.
In order to evaluate the applicability of the approach, two chemical forms of the micronutrients folate and iron were selected to demonstrate proof of principle.
“With the new approach health effects due to low and high exposure are assessed in an integrated way,” said Dr Lisette Krul, toxicologist for human risk assessment at TNO and lead author of the study.
“Since micronutrients are present in food in different forms and levels, the approach also takes differences in their bioavailability into consideration. Customised intake levels can be determined for different population groups (e.g. demographic, ethnic, age or lifestyle related) and different nutrient forms. The new method could lead to new standards. How and when these could be implemented is not clear yet."
Krul acknowledged that for the general public, average requirements (EARs), NRVs or RDA values were sufficiently adequate.
However, she believed reference values for specific population groups such as children, sportsmen, pregnant women, may need re-evaluation to determine optimal intake levels.
EFSA’s role
In the role EFSA played in determining micronutrient levels Krul said their policy to prevent unnecessary high exposure was still very important, especially if such exposure can be prevented by taking adequate measures.
“In our opinion though, the risks due to insufficient micronutrient intake should also be taken into account, e.g. by establishing levels for specific sub-populations.”
A spokesperson for EFSA was unable to comment at the current time.
Source: Critical Reviews in Food Science and Nutrition
Published online ahead of print, doi.org/10.1080/10408398.2016.1162765
“Quantifiable risk-benefit assessment of micronutrients: from theory to practice.”
Authors: Lisette Krul, Bas Kremer, Niels Lucas Luijckx, Winfried Leeman