Scientists at Germany's Federal Institute for Risk Assessment (BfR) gathered data on dietary habits in Germany and nutrient levels in the current food supply and substracted these from the upper safe levels (USL) of nutrients determined by the EU's Scientific Committee on Food.
Their conclusions, published in a 341-page report this week, suggest that supplements should contain a maximum level of 225 mg vitamin C, 5.4 mg of vitamin B6 and 9 mcg of vitamin B12. All of these vitamins are sold at considerably higher dosages - up to 1000mg for vitamin C and 300 mcg for B12 - in supplements on several European markets.
While the report is designed for review by German food authorities, it is also likely to be considered by European regulators charged with developing maximum safe levels for nutrients under both the 2002 food supplements directive and a proposed regulation on fortified foods.
No other member state has carried out such work, making the German study a valuable resource for the European Food Safety Authority in the future.
However natural healthcare association the Alliance for Natural Health (ANH) claims the data is "meaningless for the majority of the population".
The group has previously contested the science used by the SCF to draw up upper safe levels for nutrients. It says that the German institute has gone on to reduce further these levels by taking into account dietary intakes and susceptible population groups, and ended up with "unreasonably low maximum recommended levels for food supplements".
Dr Robert Verkerk, executive director of the ANH, told NutraIngredients.com: "We have always been concerned that this approach, [as proposed in article 5 of the food supplements directive], would end up with very low levels and the German report shows that it does."
David Adams, chair of the UK's Health Food Manufacturers Association (HFMA), agreed that "the figures look terribly low".
"The UK trade obviously wishes to see maximum safe levels that are in line with established UK practice," he added, noting that the assocation had had "very constructive discussions" with the UK's Food Standards Agency after an expert group (known as the EVM) produced guidance levels for supplement nutrients in 2003.
The discussions resulted in a system of advisory statements, currently found on supplement labels in the UK to warn consumers of potential risks, a welcome alternative to banning high dose supplements altogether.
The German report has clear implications for the UK industry, one of Europe's largest, which offers supplements at higher doses than many other member states.
Dr Verkerk points out a number of problems from the approach used by the BfR, particularly in their grouping together of nutrients and populations for efficiency purposes.
"If you look at iron types as a group, the data for the most toxic form is applied across the board. So the toxic ferrous sulphate impacts data on iron bisglycinate, [considered lower risk]."
"You are also looking at the most susceptible population groups, such as in the case of beta-carotene. Some of the main data on this nutrient comes from trials including smokers and asbestos workers, naturally at higher risk of disease."
Subjecting the whole population to the same risk assessment as more susceptible groups skews the safety data to levels that are unnecessarily low for most people, he suggests.
Dr Verkerk believes that regulators should initially focus on high risk nutrients as a priority.
"Risk management is about focusing energy on high risk problems. We should focus specifically on the 30-40 high risk nutrient forms, such as the fat-soluble vitamins and some potentially toxic mineral forms like selenium and zinc, and develop a risk assessment system for these as the first move forward," he said.
"But to also include vitamin B12 in this is crazy. Even the SCF could not impose a safe upper level on this nutrient."
Dutch food authorities have set a precedent for this kind of approach, added Verkerk, by allowing all supplements to be sold as food, and only imposing limits on the small number of nutrients like certain vitamins known to present risk in high doses.
"I take my hat off to the BfR. They are the only people to have taken risk assessment to the second stage, and risk is certainly far better than the previous approach to safety, using RDAs," added Dr Verkerk.
"But this will be a huge wake-up call for industry."
The German food industry association BLL said it had not had time to digest the report but noted that the findings would be open for comment and did not represent a conclusion on the issue.
Lorene Courrege, director of regulatory affairs at the European health product manufacturers association (EHPM), said she was waiting to see what the German health minister does with the report before assessing its impact on the EU food safety authority.
EFSA is aiming to produce its initial conclusions on maximum safe levels for the food supplements directive in the autumn, after the directive has actually come into force in August.
The FAO/WHO has also recently issued a consultation on the subject of risk assessment of nutrients to form the basis of Codex guidelines.