Are the children of today likely to be suffering rickets tomorrow? asks Lorraine Murphy
A new concern that has arisen for parents in recent times is low levels of vitamin D resulting from a vitamin D-deficient toddler diet. It is estimated that 70-84% of toddlers, one to four years of age have very low intakes of vitamin D. Reports detailing low levels of infantile vitamin D status raise health concerns associated with its deficiency and the linked condition of rickets.
Vitamin D deficiency is not a new phenomenon; the associated health problems linked with vitamin D deficiency are well documented and are rooted in history. Written accounts of rickets exist in Greek, Roman and Chinese literature as far back as 900BC.1 However this disease was clinically described prior to industrialisation by Glasson in 1651. As with many traditional diseases and conditions, vitamin D deficiency is now making a re-emergence with its associate, infantile rickets. Infantile rickets has come to the forefront of the Irish media emerging in 2005. This was due to the increased cases of rickets that were reported in two prominent Dublin hospitals. There were as many as 23 diagnosed cases, within a two-year period.2 Unfortunately Vitamin D deficiency hit the media at a time that coincided with H1N1 flu pandemic. The H1N1 consumed health professionals’ expertise and the finances and resources of health authorities. Due to these factors, it could be assumed that vitamin D deficiency health concerns did not benefit from the initial exposure. Perhaps if it had emerged at a time where there was not a more pressing national health issue it may have received more interest from both the health and public forum.
Vitamin D deficiency causing rickets may be the public’s perception of a condition that does not concern us in current times. However, vitamin D deficiency has many other less publicised negative health associated conditions aside from rickets. Other well documented negative health outcomes include inadequate absorption of calcium which in turn will prevent normal calcification of the bones often resulting in soft and even deformed bones. Children who do not receive adequate amounts of vitamin D are at risk from not only bone malformations but also autoimmune diseases, cancer, diabetes, dilated cardiomyopathy resulting in heart failure in children, impaired neurological function and possibly mental health conditions, namely schizophrenia.3
On clinical examination children may present with symptoms such as stunted growth, enlarged ends of long bones and ribs, abnormally shaped thorax and legs that are bow shaped. Protruding abdomen and muscle weakness is also a common symptom. The skull may be soft and enlarged with delayed closure of the fontanelles. Additional presentations may include slowly developing teeth and muscle development including delayed standing.4 These symptoms are generally identified between six months and three years of age. This highlights the importance of the relevant health professionals who provide a service to this client group to possess a proficient knowledge on this subject. The public health nurse (PHN) and general practitioner are two main health professionals who are assessing and examining children of that catchment age on a regular basis.
It is important to highlight that it is not just children who suffer the impact of vitamin D deficiency. The Framingham Heart Study suggested that adults with vitamin D levels below 35nmol/L had twice the risk of heart attack, stroke or other cardiovascular events. Vitamin D deficiency can also present as oesteomalacia in adults.4
Sources and origin of Vitamin D
The gut requires vitamin D for calcium absorption and metabolism, to enable normal bone mineralisation.5 The term vitamin D is used to refer to both ergocalciferol (vitamin D2), which originates from plants and cholecalciferol (vitamin D3) which originates from animals.6
Sunlight is the most common source of vitamin D as the skin synthesises vitamin D3 on exposure. Solar ultraviolet B radiation transforms thermally previtamin D in the skin to vitamin D3. Full body exposure for 10-15 minutes during the summer months in countries of considerable sunlight, will generate between 10,000 and 20,000iu of vitamin D in a lighter pigmented adult within 24 hours.7 Those with a darker pigmentation would require five to 10 times more exposure to generate the same levels of vitamin D. Vitamin D generation is also affected by skin pigmentation, body mass, degree of latitude, season, cloud cover and use of sunscreen.8 Notably due to the body’s ability to synthesise such levels of vitamin D and recommended supplementation levels, vitamin D toxicity is very rare.
As infants under the age of six months should not be exposed to direct sunlight, their main source of vitamin D is limited. Therefore they become reliant on acquiring their vitamin D from either food or supplementation. Vitamin D unfortunately can only be found in a limited number of foods. These foods include oily fish, egg yolk and liver however, they have relatively little impact on the overall level of vitamin D.2 Due to the limited number of foods and types that contain vitamin D and their impact on levels in the body, it poses a significant challenge to parents to ensure their child is receiving sufficient amounts of vitamin D without being supplemented.
Vitamin D absorption
Factors that have impeded satisfactory levels of vitamin D synthesis include the low levels of sunlight in the winter, and summer that Ireland experiences. The culture within Ireland is changing lifestyle has evolved towards more sedentary, indoor based activities. The advocacy of sunscreen has had an impact on individual’s vitamin D levels.
It has been identified that some ethnic groups are more at risk primarily due to the fact that more ultraviolet light is required to generate adequate vitamin D in those with darker skin due to increased melanin pigmentation.9 With the result that individuals from certain ethnic groups are at greater risk such as south Asian an Afro-Caribbean adults and children. Cultural practices can also influence vitamin D levels, certain forms of dress that limit the skins exposure to sunlight are known to have an impact on vitamin D status.
Currently the FSAI recommend that all infants in Ireland, irrespective of how they are fed should receive a minimum supplement of 5ug of vitamin D every day from birth to 12 months of age.2 At present there are no specific national guidelines for vitamin D supplementation for pregnant women in Ireland. The 2007 Survey of Lifestyle Attitudes and Nutrition Survey (SLAN) suggests that the average intake of vitamin D of women of reproductive age was well below recommended intake.
The UK Department of Health is addressing this issue of vitamin D deficiency with a slightly different approach. It has formulated Vitamin D supplementation guidelines identifying ‘at risk groups’. Detailed in these groups are pregnant and breastfeeding women, infants under five years of age, over 65 years of age, people who have darker skin, people who have low or no exposure to sunlight. These guidelines are in situ to assist in preventing negative health consequences associated with vitamin D deficiency.
This advice and information on vitamin D supplementation was disseminated to all relevant health professionals. In line with NICE guidelines10 midwives offer parents literature and advice on vitamin D supplementation at pregnancy booking appointment. Additionally, they recommend that all infants and young children aged six months to five years should take a daily supplement of vitamin D in the form of vitamin drops to help meet the requirement of 7-8.5 micrograms of vitamin D per day. An infant who is formula fed will not require supplementation unless consuming less than 500mls of infant formula a day. Their government initiated a Healthy Start Scheme where free vitamin D supplements can be obtained, in situations where a family may be experiencing financial constraints.
There is a parent information leaflet available in Ireland on Vitamin D supplementation for children. However, currently there is no information leaflet addressing the subject in relation to toddlers, pregnant and breastfeeding women, people of darker skin or individuals over 65 years of age. As Ireland and the UK are at the same latitude and have similar ethnic groups one might assume that both countries would have very similar guidelines.
Advice from health professionals to parents regarding supplementation
It is clear that vitamin D supplementation can assist in preventing a plethora of conditions. It would appear rather logical to ensure thorough guidelines are set out with the information disseminated to all relevant health professionals and the population at large. A study carried out in the UK examined the advice that a particular health professional group give to parents on vitamin supplementation. It demonstrated that the majority were advising in accordance with government recommendations.5 However a similar study carried out in Ireland in 2008-2009 (carried out by the author) examined the knowledge imparted by a congruous health profession. This study highlighted that the majority were not advising parents in accordance with recommendations from the FSAI.11 Additionally, it noted that some ethnic groups were identified at greater risk of developing rickets.11 This is not a reflection on the profession, rather it depicts the lack of formal knowledge departed to health professionals.
Vitamin D recommendations in Ireland have changed in recent years. Now there is a blanket recommendation on vitamin D supplementation. The fact that the H1N1 flu pandemic reached the media at almost the same time as the concerns surrounding vitamin D deficiency meant that the message was diluted as the flu pandemic consumed the public forum. The subject of vitamin D is now only coming to the forefront slowly again. It would appear requisite that a health-professional directed document be formulated and circulated.
The FSAI has set out guidelines for the vitamin D supplementation of infants. Due to new research emerging on the effects of vitamin D deficiency and how easy it is to address and prevent this deficiency. The Food Safety Authority of Ireland have identified that their guidelines are for review at a later date. Additionally, the emergence of the findings of SLAN may fuel new policy in relation to women of reproductive age in Ireland. Perhaps the revised guidelines may be issued on reflection of those that exist in the UK. However the FSAI should be applauded for delivering a comprehensive guide for healthcare professionals on best practice for infant feeding.12 This accompanied by Scientific Recommendations for a National Infant feeding Policy13 has been a great achievement.
Finally, symptoms of rickets and vitamin D deficiency most commonly present between six months and three years of age. It is at this age that PHN’s are monitoring growth and development of children. Growth failure and bone malformation is a typical primary presentation of rickets. This highlights that the PHN may be the first health professional to recognise vitamin D deficiency or rickets.
Along with PHN’s, midwives and GPs should also be considered the key practitioners to whom information on vitamin D, and recommendations surrounding vitamin D supplementation, should be disseminated to. This would ensure that individuals and parents are receiving consistent, evidence-based advice. Taking all factors into account it would appear that vitamin D supplementation is the most realistic achievable source of obtaining recommended levels of vitamin D.
Lorraine Murphy is a PHN for HSE South Meath and completed a thesis on vitamin D supplementation in UCD in 2010
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