Low plasma vitamin D in Asian toddlers in BritainBMJ 1999; 318 doi: https://doi.org/10.1136/bmj.318.7175.2 (Published 02 January 1999) Cite this as: BMJ 1999;318:2
If in doubt give vitamins; consider iron too, and remember other vulnerable children
- B A Wharton, Honorary professor.
Although frank rickets is now uncommon, a steady (some think increasing) trickle of new cases remains, and many local studies have shown high prevalences of suboptimal plasma vitamin 25-OH cholecalciferol (<=25 nmol/l) concentrations, particularly in winter. A paper this week by Lawson and Thomas (p 28) confirms a high prevalence (20-34%) in a representative sample of 618 Asian toddlers aged 11/2-21/2 years.1 Does this matter and what can we do about it?
Whether a low concentration of vitamin D itself is harmful is not known. The appearance of radiological abnormalities may depend on other factors affecting the availability of dietary calcium as well as vitamin D. We should be wary of chasing biochemical normality without evidence of clinical benefit, particularly if substances which are toxic in high doses have to be used. The overenthusiastic use of vitamin D supplements and fortified infant foods led to an epidemic of infant hypercalcaemia 40 years ago, with significant mortality and neurological deficit.2
The association of low plasma vitamin D and iron deficiency anaemia shown by Lawson and Thomas confirms a previous smaller study in which a third of Asian children with anaemia were also vitamin D deficient and half those with D deficiency were anaemic.3 Is this association merely two effects of diets providing little of both nutrients? Or are the two deficiencies causal—for example, via an effect of iron deficiency on vitamin D absorption4 or an effect of vitamin D deficiency on the bone marrow?5 Whatever the causes of the association, if one deficiency is suspected the other should be considered too.
How can we improve the vitamin D status of children without undue risk? There are five approaches to preventing a nutrient deficiency.
Screening (by estimating plasma vitamin D or wrist radiographs) is hardly feasible.
Health education should encourage the value of playing out of doors and eating foods containing vitamin D. In Cincinnati (lat 38=B0N) 20 minutes a day out of doors with exposed hands and face were enough to maintain satisfactory vitamin D levels in older infants6; the necessary exposure times in Britain (lat 50-58=B0N) have not been determined. Natural dietary sources of vitamin D are egg yolk and fatty fish (salmon, sardines, pilchards), but greater intakes are obtained from fortified foods and supplements (see below).
Fiscal measures —Families receiving some state benefits may receive free vitamin D fortified infant formula (during infancy only) and free vitamin supplements for children up to the age of 5.
Food fortification —Fortified breakfast cereals and margarine provide some extra vitamin D. Toddlers will not usually be drinking vitamin D fortified infant formulas or follow on formulas but, as with iron, if there are concerns about vitamin D there are arguments for toddlers using them too.7 The fortification of “doorstep” milk for children might be reconsidered; some evaporated milks are fortified with vitamin D. Foods available under the Welfare Food Regulations should include follow on formulas fortified with vitamin D and iron for toddlers, not cows' milk alone as at present.
Supplementation (through the provision of vitamin drops)—Despite our uncertainty about how many children with low plasma vitamin D values proceed to frank rickets, a modest supplement of vitamin D (the Department of Health drops provide 7 =B5g/day) is safe and effective in preventing rickets.8 The aim is that all pregnant women and children up to the age of 5 should receive a vitamin D supplement unless their professional adviser is confident that they are getting enough from the sun and diet.
Most pregnant Asian mothers and young children should receive a supplement and so should many white children living in northern Britain. Twice as many Asian as white toddlers receive vitamin drops—about half of them at 15 months9—and probably many more would benefit. There are logistic problems over supplements. The Department of Health's vitamin drops (A, D, and C) are available cheaply or free, but only in health centres. The doctor may give a prescription or advise on an over the counter product. The British National Formulary does not, however, contain a product containing only vitamin D. Most combined vitamin supplements are now not routinely prescribable under the NHS but a few have remained on the list. Since low plasma vitamin D and iron deficiency anaemia often coexist a combined supplement would be convenient. But products containing both vitamin D and iron are prescribable (with approval by the Advisory Committee on Borderline Substances) only for children with disorders of appetite, the gut, or metabolic disease; since they also contain many micronutrients, necessary for these disorders, they are also more expensive. There are many over the counter products containing vitamin D and iron, together with other vitamins or minerals, in doses providing a reasonable proportion of the reference nutrient intake for toddlers (vitamin D 7 =B5g, iron 7 mg). Thus we have Department of Health products, which are free or cheap but available only from health centres; a few prescribable products, though some only for specific disorders; and over the counter products—how complicated.
Surveillance and monitoring, policy delivery and compliance, micronutrient interactions, the Welfare Food Scheme, and prescription regulation—there are questions here for parents, health professionals, the Department of Health, scientists, and manufacturers. Isn't it time to get all the cooks together and try again to put Britain's vitamin house in order?
Competing interests—I have contributed to some of the publications quoted 2 3 7 ; I now work in the same centre as Dr Lawson1; from time to time I give opinions, for which I receive a fee, to companies making nutritional products for children