The new report from the Federal Institute for Risk Assessment (BfR) suggests the new 20 µg/day limit—a big drop from EFSA’s Tolerable Upper Intake Level of 100 µg/day (4,000 IU)—as a result of health concerns related to intermittent ‘bolus’ dosing.
The German body is said to be “pushing for the same approach across Europe” as the European Commission has not yet set harmonized legal maximum levels for vitamin D in supplements.
Daily supplementation is the standard recommendation across most European guidelines, but there are some products available providing ‘bolus doses’ of up to 50,000 IU, marketed to be taken once a week or once a month for a short period of time.
Bolus dose supplements
The BfR report noted research indicating very high bolus doses of vitamin D can increase the risk of falls and bone fractures.
It said the risk of administration errors increases with dietary supplements intended to be taken at specific intervals as they can inadvertently be taken too frequently—whereas it notes less concern over medications, which are taken under medical supervision.
“In principle, it cannot be ruled out that consumers may even take products intended as bolus doses at specific intervals on a daily basis, as daily intake is common practice for food supplements,” it stated.
The report warned that daily intake would result in a significant excess of the UL and that even a slight long-term excess of the UL can lead to adverse health effects, such as hypercalcemia. In the case of persistent hypercalcemia, this can lead to kidney stones, renal calcification, and ultimately to a decrease in kidney function.
The BfR recommended a low daily dosage, suggesting the maximum amount in dietary supplements should be no more than 20 µg daily, “as this is not expected to pose any long-term health risks, even when considering other sources of vitamin D.”
It added that bolus doses of vitamin D and vitamin K should only be taken on medical advice and under medical supervision due to the lack of research into the safety of these combined vitamins.
Luca Bucchini, food risk scientist and regulatory expert, said Germany’s proposed maximum amounts for vitamin D are “very low indeed.”
“They are based on several assumptions that are not backed by evidence,” he told NutraIngredients. “There is a serious risk, if implemented, that German consumers would not be able to get enough vitamin D from supplements, if they follow label instructions.”
Most Member States that have maximum limits based on EFSA’s Upper Level, have set them at 50 or 75 ug/day but Germany is “pushing very hard” to go lower, Bucchini noted.
“Unfortunately, Germany is pushing for the same approach at the European level,” he said. “There is ongoing work at the European level, and if no consensus is reached, it is possible that Germany would legislate the 20 µg/day limit in their laws.”
Daily versus bolus dosing
Bucchini agreed the question of how bolus doses impact the body is an important one to answer.
“Indeed, over the years, to deal with maximum amounts permitted in countries such as Italy or France (50 µg or 2,000 IU per day), companies have started employing the bolus concept for supplements,” he said. “A food supplement that in the UK or Germany would deliver 100 µg or 4,000 IU per day is labeled for France for use every other day with resulting daily amount of 50 µg/day, so it is compliant.”
He said there has been no consensus over whether this approach is compatible with the Food Supplement Directive as the directive, “seems to imply that you cannot average maximum amounts over several days if the serving has a more concentrated vitamin”.
Samantha Christie, PhD, scientific advisor for the Council for Responsible Nutrition UK with over 20 years of experience in consumer health, told NutraIngredients that vitamin D insufficiency and deficiency is of growing concern.
“Safe levels of food supplements help bridge this widening dietary gap for most UK age cohorts,“ she said. ”Responsible food supplement manufacturers, retailers and online businesses already adhere to the upper safe level set by EFSA to protect consumers and reduce the risk of unwanted effects.”
Martin Hewison, Emeritus Professor at the University of Birmingham and a leading global expert on vitamin D, told NutraIngredients he could not see the report having a major impact on supplementation recommendations.
“The greatest interest is in preventing widespread vitamin D deficiency and further exploration of the health effects of vitamin D beyond bone,” he said. “For example, there is growing interest in how to tailor vitamin D recommendations in the face of increasing rates of obesity. I have a feeling that these aspects of vitamin D will be more prominent over the next years or so.”
BfR investigation
The BfR investigated whether the intake of food supplements (NEM) containing high bolus doses of vitamin D, even in combination with high doses of vitamin K2, at longer intervals poses health risks.
Various dosages of commercially available products were evaluated: vitamin D3 with a recommended intake of 175 µg every 7 days; vitamin D3 + vitamin K2 in combination as a bolus dose with a recommended intake of 250 µg vitamin D3 and 200 µg vitamin K2 every 10 days; vitamin D3 + vitamin K2 in combination as a bolus dose with a recommended intake of 500 µg vitamin D3 and 200 µg vitamin K2 every 20 days.
The report assessed studies on the effectiveness of daily vitamin D doses compared to bolus doses in maintaining optimal vitamin D levels.
It stated that, regardless of the dosage interval, large bolus doses of vitamin D are expected to cause significant fluctuations in serum levels of the parent substance, cholecalciferol, which may be associated with undesirable effects, including impaired induction of immunologically active substances.
