Feb 19, 2014

Shiny Happy People: Vitamin D - Are you getting yours?

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This blog takes a look at some of the interesting facts about Vitamin D. But first, have a look at the infographic we've produced as a snapshot of the market here in Britain.

Vitamin D - AKA 'The sunshine vitamin' allows our bodies to absorb calcium, iron, magnesium and zinc, so it is crucial for tooth and bone development. 80% of our Vit D is synthesised by our bodies when our skin is exposed to sunlight, so the further we live from the equator, the more we rely on our diet for the remaining 20%. Although Vit D was discovered in the early 1900s, still more is being discovered about its role in diseases affecting the young and the old - diseases such as osteoporosis, multiple sclerosis and even diabetes.

RICKETS: A HORROR RETURNS

Over the past few years, doctors and public health workers have been saddened to discover the Vit D deficiency disease, rickets, making a comeback. Rickets is characterised by misformed bones, dental problems, and muscle weakness. It occurs when the process of mineralisation behind bone growth goes wrong. This may be due to over-use of sun block, not getting out into the sun enough, or for cultural reasons involving covering the skin. Despite having high sunshine levels, the Middle East has the highest rates of rickets in the world due to cultural practices, and a lack of Vit D supplementation for breast-feeding women. The good news is that rickets is reversible if children are treated with Vit D, and the results are miraculously quick in terms of treating any muscle weakness.

FORTIFIED BRITAIN?

In England, during the decades following the introduction of food fortification in the 1940s, when Vit D was added to margarine and some cereals, it was thought rickets had been wiped out, but it reappeared after the 1970s when different ethnic groups migrated to the UK: Children of Asian, Afro-Caribbean and Middle Eastern parents have darker skin, which needs more sunlight to get enough Vit D, so these children were more likely to get rickets. In 2010, the BJM reported that doctors in Newcastle (where sunlight levels are lower than in the South) were seeing 20 cases per year. It would seem that good patient education for this entirely preventable disease is of great importance once again. But, is supplementation or food fortification also needed? With our wealth of ethnicity, and so many variations in our diet, some say that fortification would fail to provide a 'catch all' approach. Yet, as a nation, we don't seem to have taken Vit D deficiency to heart. In 1999, Britain was the only EU country that didn't have an RDA (recommended daily allowance) for Vit D.

BABIES, CHILDREN, 65+

In England, all pregnant and breastfeeding mothers are advised to take daily 10mg Vit D supplements to ensure adequate foetal stores for early infancy, addressing the fact we live in a climate where sunlight levels are low. (Observational studies have shown that a mother's Vit D level during pregnancy can even influence the growth of infants. Southampton University is carrying out randomised controlled trials of Vit D supplementation for pregnant women to find out more.) In addition, Vit D drops are advised for children aged 6 months to 5 years. Yet, recent research commissioned by BUPA points to only 1 in 25 parents giving them.

As people aged 65+ years are not exposed to much sun, they too should take a daily supplement containing 10mg Vit D to avoid osteoporosis and bone fractures. (Daily supplements are more effective than weekly ones.)

CAN'T BITE, CAN'T FIGHT.

We've come a long way in the past 100 years in our understanding of nutrition. When soldiers were recruited to fight in the Boer War (1899 - 1902) of the 8,000 sourced from Manchester, 6,800 displayed signs of incapacity caused by a childhood illness such as rickets, presenting significant implications from a military point of view. Such was the poor state of the recruits' teeth thanks to a lack of Vit D (and poor oral hygiene) the term, 'can't bite, can't fight' arose. Intriguingly, though, medics noted that Scotsmen fared better than most recruits - which the Scots themselves attributed to habitual doses of cod liver oil, even before Vit D had been discovered. The Scots' belief was dismissed as an old wives' tale, and sadly it took several decades before the truth was out: Oily fish does contains high levels of Vit D.

Today, with genetic profiling and other laboratory techniques, we are discovering even more benefits of the sunshine vitamin.

The highly debilitating disease, multiple sclerosis (MS), has been implicated in lack of Vit D for some time. This is a disease almost unheard of near the equator, with incidence rising incrementally towards the poles. Although MS affects women more than men, as long ago as the 1960s, it was noted by the military (which keeps large data sets of long-term medical records) that a healthy, outdoor lifestyle amongst US veterans provided the ideal protection from MS.

NEVER MIND THE STAR SIGN

The powerful effect of the seasons - ergo, Vit D levels - can also be seen in the number of people suffering from immune disorders. Even within Britain, there is a north-south divide in the incidence of such diseases, with more cases the further north you look. In the 1980s, Vit D was found to normalise blood glucose levels by increasing insulin release. Then in the 1990s, the link was established between the seasons and glycaemia (blood glucose). Now, it has been proven that adequate Vit D reduces the risk of type 1 diabetes because it suppresses acquired immunity. As for Type 2 diabetes, Vit D can help decrease insulin resistance (the first feature of this increasingly common, and enormously costly, disease).

In the light of the above, you may wish to know that April is the least 'lucky' month in which to be born: Should your birthday fall around then, your mother will have spent the majority of her pregnancy without much exposure to sunlight. (Unless she's been jetting off to the Caribbean, of course...)

THE SPORTS CONNECTION

Lately, there's been an increased focus on the link between Vit D and athletic performance. Dr Graeme L Close, Senior Lecturer in Sports Nutrition at Munster Rugby, has been asking: Why do jockeys (known for their leanness) have far lower levels of Vit D than their bulky brethren, the rugby player? He is testing the hypothesis that the answer may lie with Vit D's role in muscle mass. Certainly, ballet dancers who are given Vit D supplements (as opposed to a placebo) were found to be able to increase their vertical jump height and lower their injury rate. Now that must be a good pointe...

INDOOR LIVES: A TICKING TIME BOMB?

We know that lifestyle changes over the past 50 years have affected our health immeasurably, as seen with obesity and the corresponding diabetes epidemic, amongst other diseases. Are we facing a ticking time bomb of Vit D deficiency that's storing up problems for later life as children and young adults replace outdoor time with time spent indoors on computer games? Perhaps we should get kids outside with their handheld devices and take full advantage of the wireless era!

Further research into Vit D's effects on health are needed. A key problem is controlling the trials effectively because Vit D isn't like a measurable drug, able to be monitored accurately precisely because we can synthesise it from sun exposure. Yet, the message is not to give up, afterall, it took 40 years for the medical world to accept that sunshine would prevent rickets.

In the meantime, we can take comfort during these long winter months that dark chocolate is high in Vit D. Now, that's a win-win situation.