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The vitamin D dilemma

‘The double-edged sword of vitamin D in Ireland.’

This title of a study published last year aptly described the dilemma surrounding a vitamin that is fundamental to bone health. On the one hand, there is a need for public health awareness about having too little — and on the other, about having too much.

Internationally, vitamin D is the subject of ongoing debate, with matters of contention surrounding the scope of non-skeletal effects, optimal levels and even the serum 250HD (25-Hydroxyvitamin D) cut-off levels that define sufficiency and insufficiency.

Kilbane et al in the Irish Journal of Medical Sciences (‘The double-edged sword of vitamin D in Ireland: the need for public health awareness about too much as well as too little’, 2014) produced findings that, in the Irish context, were highly pertinent to the complex challenge facing public health strategists.

In a retrospective audit of over 10,000 clinical samples, which utilised the classifications of the US Institute of Medicine (IOM) to establish percentages of patients with 250HD levels indicating risk of deficiency and risk of harm, the authors established a twin challenge: “High prevalence” of hypovitaminosis D (23.9 per cent) and a “substantive prevalence” of hypervitaminosis D (4.8 per cent).

The authors from St Vincent’s University Hospital, Dublin, and the Food Safety Authority of Ireland (FSAI) concluded that hypovitaminosis D should be corrected by low-dose supplementation (200IU daily), with some at-risk groups needing higher doses (400 IU daily) based on 250HD levels. “… those taking high-dose vitamin D supplements based on mistaken beliefs about recently-authorised claims of benefit for muscle function and misleading unauthorised claims need to be alerted to the potential harms of excessive supplementation,” it found.

The subject of vitamin D deficiency in Ireland is an area that bodies such as the FSAI have consistently highlighted in recent years, with a report published by the Authority in 2007 hastening the introduction of a HSE policy advocating infant supplementation of 200IU vitamin D3 daily.

High doses

The issue of over-supplementation has been much less flagged. While the FSAI notes on its website that “continuous high intakes” of vitamin D, for example, can cause kidney damage and bone deformity, the message on high-dose vitamin supplements does not appear to have been the focus of any concerted communication efforts. But documentation obtained by the Medical Independent (MI) indicates that it is of increasing concern.

Following a Freedom of Information request to the FSAI on safety concerns relating to food supplements, MI has become aware of significant anxiety within the Authority on the issue of high-dose vitamin D food supplement products. Internal correspondence shows that in December 2013, a public warning was even mooted. However, in making this suggestion, the official noted that it would need to be “handled carefully” so as not to negatively affect the national policy on vitamin D supplementation for infants. Furthermore, the official wrote that the high prevalence of “low-to-deficient vitamin D intakes in Ireland” was also a consideration.

Last week, an FSAI spokesperson told MI that this email had formed part of the “general discussion in-house about risk management options”. Further collective in-house consideration of the matter, including consultation with other scientific experts from the FSAI Scientific Committee, had “led to the conclusion that a public warning was not warranted”.

The spokesperson said the “absence of agreed upper safe limits at European level” is a disadvantage for consumer protection. In the continuing absence of such limits, the FSAI has commissioned its Scientific Committee to examine how maximum safe levels of vitamins and minerals can be established. The report of the Scientific Committee, expected this year, “will provide a transparent basis for risk assessment, which in turn will underpin the risk-management decisions”.

The Medical Independent has become aware of significant anxiety within the Authority on the issue of high-dose vitamin D food supplement products

To date, a number of bodies have issued guidance on upper tolerable levels of vitamin D, the estimated average requirement and recommended dietary allowance (RDA).

The EU RDA for nutritional labelling of food products sets vitamin D at 200IU daily. The FSAI, in its Scientific Recommendations for Healthy Eating Guidelines in Ireland (2011), considered that everyone should take a daily vitamin D supplement (200IU per day for those aged five-to-50 years and 400IU per day for those aged 51 years and over).

In 2012, the European Food Safety Authority (EFSA) announced that it had raised its vitamin D tolerable upper intake levels (ULs) for adults and adolescents from 2,000IU a day to 4,000IU a day; the UL for children aged one-to-10 was increased from 1,000IU a day to 2,000IU a day. These levels refer to intake from all sources.

A UL is not a recommended level of intake; rather, it is the maximum level of total chronic daily intake of a nutrient (from all sources) judged to be unlikely to pose a risk of adverse health effects to humans. It is an estimate of the highest level of intake that carries no appreciable risk of adverse health effects.

A report in 2010 from the IOM determined that 600IU per day of vitamin D would meet the needs of almost anyone in the US and Canada. In establishing DRIs (dietary reference intakes), the IOM committee assumed minimal sun exposure. The report established the estimated average requirement at 400IU a day from the age of one, while the upper-level intake from the age of nine was 4,000IU (and lower for infants and babies).

With such intakes in mind, it is unsurprising that products reaching the Irish market, advocating daily doses of 4,000IU and 5,000IU of vitamin D, have sparked concern.

The issue attracts further complexity when considering that, as outlined in Irish regulations, products containing in excess of 3,000IU vitamin D as a maximum daily dose require a prescription.

However, the HPRA understands that the Department of Health position is that the inclusion of a vitamin in the Schedules to the Medicinal Products (Prescription and Control of Supply) Regulations does not necessarily imply that the vitamin is a medicine. According to the HPRA: “Vitamins are considered to be medicinal products when their labelling and accompanying, or associated literature, make preventative, curative or remedial claims.”

The HPRA spokesperson notes that the European Communities (Food Supplements) Regulations set out those vitamins and minerals which may be used in the manufacture of food supplements. Vitamin D (cholecalciferol and ergocalciferol) are included in these regulations. “It is intended to introduce maximum safe upper limits for the vitamin and mineral supplements listed in the regulations. These limits and recommendations for food supplements are the responsibility of the European Food Safety Authority (EFSA), and the Food Safety Authority of Ireland (FSAI) implements and supervises this legislation on a national level.

“Once maximum safe upper limits have been determined, products containing vitamin and mineral supplements at levels up to these upper safe limits can be legitimately marketed under food legislation; products that exceed the upper safe limit will not be permitted as food supplements.”

A FSAI Risk Assessment of six high-dose vitamin D supplements, dated 23 January, 2014, and seen by MI, referred to four products notified to the FSAI and two reported to the FSAI as being on the Irish market, without having been notified. Three of the products recommended a daily amount of 4,000IU, while three recommended 5,000IU. Furthermore, two of the three 5,000IU products were not notified to the FSAI.


The risk assessment by Dr Mary Flynn, FSAI Chief Specialist in Public Health Nutrition (PHN), and consultant endocrinologist Dr Malachi McKenna, a member of the FSAI PHN sub-committee, stated that the vitamin D levels provided by all of these products (as indicated on the labels) raised concerns that the use of the supplement in combination with average dietary intake in Ireland would result in intake levels in excess of ULs.

“None of the six food supplement products in this risk assessment warn consumers about the need to avoid other food supplements containing vitamin D,” it said. “…There are no contraindications on the labels to warn parents that these products are not suitable for children.”

In an especially strongly-worded paragraph, the risk assessment reported: “It would be considered cavalier and contrary to all the evidence of risk of harm to allow a product on the market that allowed a member of the public to self-administer a supplemental dose that would permit their total vitamin D intake to be in excess of the UL and to be a multiple of the RDA.”

On potential side-effects associated with excess vitamin D, the document noted “increasing evidence” of non-metabolic adverse effects of vitamin D toxicity, “independent of hypercalcaemia and hypercalciuria effects”.

Correspondence indicates that the FSAI contacted the makers of the products, requesting details on their location and availability in Ireland and advising that they were unsafe. Yet consultation with the FSA (Food Standards Agency) in the UK indicated that the FSA did not have health concerns about vitamin D products containing 4,000IU per daily dose, although it considered products containing 5,000IU to be of some concern.

I would generally like to see all healthy Irish children and adults achieve adequate vitamin D intake from fortified foodstuffs rather than resorting to supplements

In May 2014, communication between FSAI officials referred to lab results, which had found that two vitamin D food supplement products, both recommending a daily amount of 4,000IU, were 43 per cent and 47 per cent above the daily upper safe level, respectively. It appeared from the partially-redacted correspondence that these two tested products were among those that were risk-assessed in the document from January 2014.

Last week, a spokesperson for the FSAI told MI that it considers the safety of supplement products with high doses of vitamins or minerals on a “case-by-case basis”. According to the spokesperson, in such cases a risk assessment will be carried out, taking into account criteria such as the opinions and reports of the EFSA on upper limits; the reports of the Institute of Medicine (IOM); acceptable tolerance levels for essential ingredients; knowledge of exposure and food intakes of population groups in Ireland; intended population target groups; manufacturer’s recommended dose; and product labelling.

According to the FSAI, in the time that MI provided, it was not possible to verify how many products exceeding or meeting ULs were on the Irish market during the period 1 January, 2013, to date.

The spokesperson confirmed that notification of food supplements is a statutory requirement. Notifications can be completed online and should be done when a food supplement is placed on the Irish market for the first time.

The duty to notify falls on the manufacturer if the product is manufactured in Ireland, and on the importer if the product is imported into Ireland.

In respect of products in excess of ULs placed on the market without notifying the FSAI, the spokesperson told MI: “When the FSAI becomes aware of a food supplement which is on the market and which was not formally notified, the business operator is contacted and asked to make a notification. The FSAI will also conduct a risk assessment on the product.”

But she added: “It should however be noted that tolerable upper limits are not set in either national or EU food legislation. It remains a matter, in the first instance, for the food business operator to ensure the safety of any food/food supplement he/she places on the market.”

Asked how the FSAI satisfies itself that all food supplement products on the Irish market have vitamin levels that correspond with the label information, she commented: “Legally, in the first instance it is a matter for the food business to ensure that their products are safe and comply with legal requirements. As part of the annual programme for food surveillance, the HSE, an official agent of the FSAI, samples and analyses food supplements on the market in Ireland.”

On the number of adverse events associated with food supplements reported to the FSAI during 2014, the spokesperson said that the HPRA had reported to the FSAI three adverse reactions relating to food supplements. These concerned krill oil, green tea extract and a multivitamin.

Policy on infants prompted by re-emergence of rickets in Ireland

At present, Irish public health policy on vitamin D supplementation is limited to infants aged up to 12 months. This age cohort should be given a daily supplement of 200IU vitamin D3, irrespective of whether the infant is breast- or formula-fed; the dose should be provided by a supplement containing vitamin D exclusively.

The HSE Policy on Vitamin D Supplementation for Infants in Ireland (2010) states that information should be given to all expectant and new mothers in oral and written formats “during the health service maternity and childcare journey”. The provision of this information should be documented in the mother’s nursing and medical records and signed.

The HSE says research has demonstrated the success of the policy.

The policy followed a report published by the Food Safety Authority of Ireland (FSAI), Recommendations for a National Policy on Vitamin D Supplementation for Infants in Ireland (2007), which detailed vitamin D considerations from an Irish perspective. The re-emergence of rickets among infants in Ireland prompted the report, which described as “urgent” the need for a policy for this cohort.

The FSAI paper also referred to accumulating evidence that indicated vitamin D as having a possible role in the prevention of serious chronic diseases affecting the Irish population, including cardiovascular disease; diabetes mellitus; some inflammatory and autoimmune disorders; and some types of cancer.

The paper noted that the main source of vitamin D is synthesised in the body through the action of ultraviolet B (UVB) rays in sunlight on the skin.

Due to Ireland’s northerly latitude, very little UVB light reaches the earth’s surface, resulting in reduced production of vitamin D, especially in winter. “This fact, in conjunction with low dietary intakes, is compromising the vitamin D status of all groups of the population living in Ireland.

“Indeed, other countries with latitudes similar to that of Ireland, eg Canada, have already identified and addressed the problem of vitamin D deficiency by putting in place supplementation and/or food fortification programmes.”

The paper found that strategies to increase vitamin D intake in different age groups of the population in Ireland needed to be formulated, but infants aged 0-12 months were the urgent priority due to the re-emergence of rickets.

Rickets, a serious consequence of vitamin D deficiency that leads to major bone deformities, was thought to have been eradicated in the preceding decades. The paper noted that, as rickets represented the “extreme end” of the spectrum of vitamin D deficiency, the indication was that suboptimal levels of vitamin D were “prevalent” among infants.

Evidence was also presented on poor vitamin D status amongst adults, adolescent girls and pregnant women living in Ireland, which had a direct impact on infants because the vitamin D stores infants are born with is dependent upon their mother’s status. As infants should never be exposed to sunlight due to the risk of skin cancer, they were “entirely dependent on dietary intake for their vitamin D needs”.

Dr Malachi McKenna, Consultant Endocrinologist at St Vincent’s University Hospital — and a co-author of a study on vitamin D levels published last year in the Irish Journal of Medical Sciences — believes the national policy on infants covers this cohort amply.

In his view, the house-bound elderly should be on a low-dose calcium and vitamin D supplement (he suggests a vitamin D supplement of about 400IU a day and calcium at 500 milligrams a day, with scope to double these amounts if appropriate, “but no more than that”).

“In time, there should be a national policy on this matter, but for now it is best if this advice is individualised by GP,” Dr McKenna tells the Medical Independent (MI).

Dr McKenna would also advise lowdose vitamin D and calcium supplementation for some ethnic minority groups who are not getting any sunlight, particularly if their diet is low in calcium. There are also certain health conditions where supplementation may be required, such as refractory malabsorption syndromes.

“During the winter months, I would generally like to see all healthy Irish children and adults achieve adequate vitamin D intake from fortified foodstuffs, rather than resorting to supplements. I think that would amply take care of their vitamin D requirements,” adds Dr McKenna.

The adverse effects of low vitamin D are “a little bit contentious,” although the bone and mineral effect is “very well established”. Dr McKenna says that an extreme outcome, as noted, is rickets in children or osteomalacia in adults. Milder effects can include lower bone density and increased risk of fracture.

“There is a lot of evidence showing association between vitamin D deficiency and what we call non-skeletal diseases,” he continues. While there are statistically-significant associations, as yet causality has not been established. “There are some links with autoimmune diseases — multiple sclerosis is the most commonly quoted, with infection — tuberculosis being one, with risk of cancer, and even with overall life expectancy. We are still waiting for results of ongoing clinical trials in order to prove that vitamin D supplementation can offset the risk of non-skeletal diseases.”

As Dr McKenna corroborates, some people are taking extremely high doses of vitamin D, potentially endangering their health.

In the study in the Irish Journal of Medical Sciences, reference was made to samples from three individuals, originating in general practice. One was from a young sportsman whose 25OHD level was 750nmol/L (a level above 125nmol/L indicates risk of harm, according to the IOM); a second from an individual undergoing treatment for prostate cancer with a 250HD of 1,389nmol/L; and a third from an MS sufferer with a 250HD of 915nmol/L.

“Such high levels could only be achieved by taking very large doses of vitamin D over a prolonged period of time,” stated the paper.

Dr McKenna is aware of one case where there was a “really bad outcome” arising from excess supplementation of vitamin D.

He comments: “If you ask that question about safety of high doses of vitamin D, you will get an answer where people will say [in some instances], ‘well actually, we don’t find hypercalcaemia, we don’t find kidney stones, we don’t find hypercalciuria, [therefore] it is okay take 10,000 units a day’… The right question is: How much do you need? And if someone is advocating more than 800 units daily, then you have to ask, why are you advocating more than what is required?

“Right now, we have two problems related to vitamin D in Irish society: Firstly, those at risk of vitamin D deficiency, like the elderly and ethnic minorities, who would benefit from low-dose supplementation of vitamin D and calcium; and secondly, false claims about benefits of highdose vitamin D (above 800 units daily) giving rise to a growing problem of high vitamin D intakes.”

Meanwhile, MI has been informed that the Department of Health’s Health Promotion Unit is developing a proposal for nutrition policy and one of the issues being discussed is a vitamin D policy.

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