Last year the UK’s Scientific Advisory Committee on Nutrition (SACN), which advises executive government agency Public Health England (PHE), released a draft report on vitamin D.
Current UK government advice states no additional dietary intake of vitamin D is necessary for individuals living a ‘normal lifestyle’.
The SACN draft – expected to be finalised in the next few months after a consultation process – sought to update its 2007 conclusion there was insufficient evidence to reconsider existing recommendations for vitamin D.
Since then a significant amount of evidence has been published, and the new report called for “strategies” beyond natural food sources alone to help the UK population meet upped recommended levels.
In a separate review published this month, the British Nutrition Foundation (BNF) said the pending SACN report would “no doubt stimulate debate” about the need for food fortification in the future on both a mandatory and voluntary basis.
“If we rewind 100 years or so, one of the micronutrients of most concern in the UK was vitamin D, a lack of which caused widespread occurrence of rickets amongst children,” the food industry-backed charity wrote in Nutrition Bulletin.
“This easily preventable bone disease was virtually eradicated by the 1950s with a reduction in atmospheric pollution, improvements in diet in the post-war period, alongside mandatory fortification of margarine and use of cod liver oil supplements but its re-emergence has helped to put vitamin D back in the public health spotlight.”
BNF science director Sara Stanner said with one in five people in the UK having sub-optimal vitamin D levels, it was now time to consider fortification.
“In the past we’ve said that at risk groups should be supplementing, but the problem with that is that we know that they’re not,” she told NutraIngredients.
“[So] do we focus on that message or do we actually encourage manufacturers to fortify more?”
The final SACN report would be crucial in kick starting that conversation, she said.
“We're sort of a bit in limbo at the moment because we’re waiting for the final [SACN] report and then all those discussions [with PHE] have got to be held and then hopefully we’ll come up with a plan going forward around all the issues of getting people to consume more supplements and people to get more vitamin D from fortified foods because we know we can’t really get it through natural foods, it is quite an unusual nutrient in that sense.”
Countries like sunshine-starved Sweden have already made moves on fortification.
There, rules on the mandatory fortification of a whole range of foods including dairy products, lactose-free milk alternatives and cooking oil are expected to come into force this summer after protracted redrafting of the plans.
Stanner said it was vital the UK looked to other countries to see what impact fortification schemes were having.
“Obviously fortification has increased over recent years and certainly our paper shows that that’s made a significant contribution, more and more so, to people’s micronutrients intakes. And it is increasing and it is obviously going to be a possible route.”
This went beyond vitamin D, she said, pointing to the ongoing debate around mandatory flour fortification with folic acid to prevent neural tube defects.
This issue has been rumbling on since the 1990s, when a Medical Research Council trial suggested folic acid (vitamin B9) could help reduce the risk of neural tube defects by up to 72%.
Stanner conceded progress on this had been slow in the UK though, and suggested in more recent years this was due to a public health preoccupation with obesity and sugar and fat reduction.
How deficient is deficient?
Another reason was the play off between the term ‘deficient’ and ‘suboptimal’, she said.
Deficiency triggered alarm bells, while suboptimal levels only warranted monitoring.
“Because it’s not deficiency, because it’s sub-optimal, we haven’t really had the research to say: ‘This is the functional health outcome of that.’
“And so at the moment it’s just been monitored in the population. But I think that research is starting to come through now to show that actually these suboptimal levels might be problematic.”
She said a good example of this research was a recent paper on folate levels, which suggested low maternal levels that would not influence neural tube defect risk would nonetheless impact children’s later cognitive function.
“So that sort of research is coming through and obviously that is going to have an influence on the conversation around micronutrients alongside the macronutrients.”
Rickets on the rise?
Indeed vitamin D has only really hit headlines again with the supposed re-emergence of the 'functional health outcome' of rickets.
According to the UK’s National Health Service (NHS) the number of rickets cases was still relatively small with less than 700 cases diagnosed in English hospitals in 2013-14.
However it said studies had shown a significant number of people in the UK had low levels of vitamin D in their blood.
BNF says the risk of poor musculoskeletal health is increased at serum 25(OH)D concentrations below 25 nmol per litre.
In the UK, one in five people have serum levels below this level, ranging from 7.5% in 1.5-3 year olds to 12.3% of girls and 15.6% of boys aged four to ten years, 19.7% of boys and 24.4% of girls aged 11-18 years and 24% of men and 21.7% of women aged 19-64 years.
People with darker skin such as those of African, African-Caribbean and South Asian origin are at particular risk of deficiency as are pregnant and breastfeeding women, children under five and adults over 65.
Stanner said multiculturalism in Britain would be part of the discussion once the SACN report was published.
“They are a very vulnerable group,” she said. “Even in terms of the messages and the way we put those messages out, it’s going to have to be part of the discussion because obviously everybody is not the same and we’ve got to target it in the right way.”
A list of BNF members can be found here.