Two senior paediatric pathol-ogists have discovered a vitamin D deficiency in a significant number of SIDS cases, including deaths that were otherwise thought to be suspicious.
This has led to their fear that some parents are being wrongly accused of harming and even murdering their children, when the explanation is simply a lack of enough vitamin D.
These astounding findings-made by Dr Irene Scheimberg, from the Royal London Hospital in Whitechapel, and Dr Marta Cohen, at Sheffield Children's Hospital-followed the discovery by Dr Scheimberg in 2009 of congenital rickets, a bone disease due to vitamin D deficiency, in a four-month-old baby whose parents had been accused of shaking him to death.
Chana Al-Alas, 19, and Rohan Wray, 22, were acquitted of mur-dering their son Jayden after the jury learned that his fractures, supposedly signs of abuse, could have been caused by his severe case of rickets, which his mother was also suffering from. Severe vitamin D deficiency can make the bones of small babies extremely brittle and liable to fracture with little or no real force, Dr Scheimberg said.
Jayden's case spurred an investigation into other sudden infant deaths, resulting in Dr Scheimberg's findings of a D deficiency in a further 30 cases in London; in fact, in three of the babies, vitamin D deficiency was the actual cause of death.
Meanwhile, in Yorkshire, Dr Cohen found moderate-to-severe levels of D deficiency in 45 children, mostly infants aged less than 12 months, who had apparently died of natural causes. Of the 24 SIDS cases investigated by Dr Cohen among this group, 18-or 75 per cent-proved to be deficient in vitamin D.
D deficiency and deaths
These discoveries are intriguing, particularly as D deficiency is a growing problem in the UK, but they also highlight the need for further research-a point that was made in a statement by the Foundation for the Study of Infant Deaths (FSID), a UK charity that funds such research and supports bereaved families.
FSID's scientific advisor, Professor George Haycock, said of the new findings, "We know that multiple risk factors are involved in sudden infant death and, although vitamin D deficiency is an interesting new area of research, these cases do not provide us with evidence of a single cause for sudden infant death." He added that further investigation is needed before it can be confirmed that a lack of vitamin D is another potential risk factor.
Indeed, at the moment, published studies on the subject are lacking, although there is one from back in 1980, indicating that the vitamin D-SIDS association is not a new one.
When researchers in St Louis, MO, looked at vitamin D levels in 31 SIDS cases and 24 post-mortem control infants, they found no significant differences between the two groups, and so concluded that the results "eliminate a simple vitamin D deficiency . . . as a significant contribution to the patho-physiology of SIDS" (Pediatrics, 1980; 65: 1137-9).
Nevertheless, the new evidence discovered by Drs Scheimberg and Cohen shows a plausible link that needs to be explored further. Crucially, it suggests that some sudden infant deaths could be preventable.
Other health problems, too
The new findings add weight to the recent calls for widespread vitamin D supplementation across the UK, particularly for at-risk groups
such as the under-5s. Although vitamin D supplements are already recommended for these children-as well as for the elderly
and pregnant or breastfeeding women-nearly three out of four UK parents know nothing about this advice. Worse, more than half of all healthcare professionals are also unaware, according to reports.
Recent research suggests that a quarter of all UK toddlers are low in vitamin D, and cases of rickets appear to be on the rise. But it's not just bone fractures and SIDS that are found with low levels of the vitamin. Mounting research suggests that not getting enough D can put children at risk for a whole host of health problems.
In one study from Australia, low vitamin D status was linked to food allergies and eczema in children. The researchers found that children living at latitudes with lower levels of sunlight and, therefore, low levels of vitamin D, are at an increased risk for developing allergies to eggs and peanuts, as well as the skin condition eczema, compared with children living in areas with higher levels of sunshine (J Allergy Clin Immunol, 2012 Feb 1; Epub ahead of print).
Lead researcher Dr Nick Osborne explained that "allergy incidence changed from the Northern states that are closer to the equator, where there was a low rate of incidence, and as we moved down towards the middle and then Southern states, we found the incidence was higher".
Such findings bolster the existing evidence suggesting that low levels of vitamin D could play a role in rising rates of food allergy and eczema, Dr Osborne said.
More worrying, low vitamin D status has also been linked to mental-health problems in chil-dren. A study presented at the 2011 164th Annual Meeting of the American Psychiatric Association in Honolulu, HI, found that children with severe mental-health disorders, including psychosis, were twice as likely to be deficient in vitamin D compared with mentally healthy children.
The investigators, from the Oregon Health & Science University in Portland, showed that 21 per cent of children with symptoms of severe psychiatric problems had levels below American Academy of Pediatrics recommendations.
This percentage can be compared with the 14 per cent found in children who participated in the US National Health and Nutrition Examination Survey (NHANES) III, a population-based study covering 1988 to 1994, which assessed the nutrition and health status of both children and adults in the US.
The strongest connection was between vitamin D deficiency and psychotic disorders. "The preva-lence of vitamin D deficiency (43 per cent) was most common in children with psychotic disorders compared to other mental health disorders," said Mini Zhang, one of the Oregon study authors.
Other mental health problems looked at by the study included anxiety disorders, autism, disruptive disorders and mood disorders.
Study co-author Keith Cheng revealed that, although the mechanism behind the vitamin D- mental-health connection is still unknown, it is a plausible one.
"We're still not entirely certain of the role vitamin D plays in brain function and development," Cheng said, "but we do know there are vitamin D receptor sites in various brain cells. We don't know exactly what happens when those receptor sites aren't active, but we do know they are there and that they are there for a reason."
D for diabetes
Other research suggests that not getting enough vitamin D could up the risk of diabetes in children. In a Finnish study of more than 12,000 babies followed for more than 30 years, the children who regularly took vitamin D supplements had a lower rate of type 1 diabetes than those who did not, while those suspected of having rickets-a condition linked to vitamin D deficiency-had a threefold greater risk of diabetes.
These data also showed that children regularly given the recommended dose of vitamin D (at the time, 2000 IU/day) had an 80-per-cent lower risk of having type 1 diabetes compared with those who regularly received less than the recommended amount (Lancet, 2001; 358: 1500-3).
More recently, researchers at the Stockport NHS Foundation Trust in the UK pooled the results of five separate studies assessing the effects of vitamin D supplementation in infancy on type 1 diabetes risk. They found that the children given additional vitamin D were roughly 30-per-cent less likely to develop the disease later in life compared with those not given the supplement.
Although all of the pooled studies were observational and, as such, cannot prove a cause-and-effect relationship, the researchers concluded that "vitamin D supple-mentation in early childhood may offer protection against the development of type 1 diabetes". However, they also noted that "randomized controlled trials with long periods of follow-up are needed to establish causality and the best formulation, dose, dura-tion and period of supplementa-tion" (Arch Dis Child, 2008; 93: 512-7).
Daily doses of D
These compelling studies add to the growing pile of evidence from adults showing that vitamin D can protect against a range of diseases and conditions-from heart disease to cancer-beyond those that are clearly bone-related (see also WDDTY vol 20 no 4). But how much is enough?
We often hear that getting a regular dose of sunshine is all we need to keep our D levels topped up, but our current habits of dress and lifestyle, and the recommendations made for sun avoidance to reduce the risks of skin cancer, mean that many of us aren't able to make sufficiently healthy amounts of this vitamin. Moreover, during the winter months, sunshine levels in Northern countries such as the UK are so weak that our bodies are barely able to make any vitamin D at all.
Young children are especially at risk from vitamin D deficiency, and daily supplements are currently recommended for this population group in the UK. However, some experts say the current dosing guidelines (280-340 IU/day for children aged six months to five years) are too low. In the US, the recommended amount is slightly higher at 400 IU/day, yet vitamin D researcher Adrian Gombart, from Oregon State University, still believes that this is "probably not enough". He reckons that between 800 and 1000 IU every day would be more effective for helping the fight against disease.
Factfile: Vitamin D2 vs D3
Two types of vitamin D supplements are available over the counter: vitamin D2, or 'ergo-calciferol'; and vitamin D3, or 'cholecalciferol'. Most experts now believe that vitamin D3 is preferable. In a recent review, Dr Mark Moyad, from the University of Michigan Medical Center in Ann Arbor, explained why (Dermatol Nurs, 2009; 21: 25-30, 55).
- UVB light from the sun strikes the skin, allowing humans to synthesize vitamin D3, so it's the most 'natural' form of vitamin D. Humans never make vitamin D2, whereas most healthy fish contain vitamin D3.
- Vitamin D3 may be less toxic than D2 because higher concentrations of D2 circulate in the blood when taken (compared with vitamin D3). It also doesn't bind as well to receptors in human tissues compared with vitamin D3.
- Vitamin D3 is the more potent form of vitamin D, which is a potential benefit; for example, obesity tends to lower blood levels of vitamin D, so a more potent form is needed to maintain health.
- Vitamin D3 is more stable on the shelf compared with D2 and, therefore, is more likely to remain active for longer periods of time and when exposed to different conditions (temperature, humidity, storage).
- Vitamin D3 has been the most utilized form of vitamin D in clinical trials.
- Vitamin D3 is better for raising and maintaining levels of vitamin D in the circulation.
WDDTY Vol. 22, 12. March 2012