Vitamin D guys, like what’s the Deal?

I hope you all revelled in the Paddy’s Day celebrations over the weekend. Ireland was ablaze with shamrock, parades and rugby, but sadly not sunshine. Indeed, the sun has been all tease and very little please in recent weeks in Dublin’s fair city but at least it’s finally honouring us with the odd cameo, thereby heralding the real start of Spring. I now feel obliged to plot and plan my Summer #Holidaze and I’m hoping for abundant sun and with it, the sunshine vitamin, good old Vitamin D.



Formentera 2016: #HappyPlace


In this age of daily spandex-new health trends, Vitamin D is an old and familiar topic. Yet it continues to crop up again and again, without any pattern or rhythm. I’m often asked about it by friends and family; sure who better than the Irish to jump on an unpredictably-timetabled bandwagon every time it comes round?!


Here we go again…


I’m going to make this brief and focus on the vitamin D requirements (#Need) of the general (i.e. otherwise healthy) population. (Those most at risk of deficiency include people with little or no sun exposure, those with darker skin, pregnant ladies, breastfed babies, and those with malabsorption syndromes such as coeliac and inflammatory bowel disease.)

The BMJ (British Medical Journal) published an article in November ’16 entitled: ‘Should healthy people take a vitamin D supplement in winter months?’ which concluded that we should indeed take one and that ‘the amount that is sufficient to meet the needs of 97.5% of the population’ is ’10 mcg (400 International Units) a day to protect musculoskeletal health in people aged 4 years or older’.

Vitamin D is produced in the skin from cholesterol in response to sunlight (specifically UVB radiation). It is oil-soluble, so you must eat fat (yay!) in order to absorb it: #LicenceToFill. There are limited dietary sources: fatty fish (tuna, mackerel and salmon… #SalmonAgainAndAgain), egg yolk, red meat, liver, cheese (#YesPlease), mushrooms (sunlight-exposed ones: #Isn’tItWellForThem) and certain souped-up foods (fortified cereals, orange juice, milk and other dairy products… check the ingredients guys).


[pic from]

Like human skin, mushrooms can transform UVB radiation into vitamin D even after they’ve been picked… #VacationGoals   [Picture credit:]

In a country like Ireland, your body produces very little vitamin D in winter months. However, we can thankfully squirrel away adequate amounts to see us through 30-60 days at a time, #MorePowerToUs.

Vitamin D is actually a pro-hormone: an essentially inactive precursor of a hormone that floats around in our bloodstream awaiting its arrival at the liver and kidneys where enzymes pounce in order to render it active.

We need it to ensure that our bowels absorb sufficient quantities of calcium (and iron, magnesium, phosphate and zinc, but calcium is the main player here) to keep us keeping on. (Calcium is involved in pretty much every single damn thing that goes on the body unbeknownst to our good selves, including the formation of teeth and bone, muscle contraction, blood clotting, the rhythmic beating of the heart and it also gives thousands of bodily enzymes a well elbow-greased hand in their thousands of chemical reactions every thousandth of a second… #BusyBusyBee.)

There are no consistent international guidelines on the need for vitamin D supplementation, #NothingNewThereSezYou… I feel this is forgivable in this particular scenario given sunlight’s attendant skin cancer risk… Exercise a commonsensical approach to maintain the balance between safe sun exposure and vitamin D production people! The World Health Organisation advises 5-15 minutes of casual sun exposure to hands, face and arms 2-3 times weekly during the summer.



image via Pinterest


If push came to shove, I’d be inclined to row in with the advice from Public Health England: a typical daily intake of 400 IU (International Units) or 10mcg. (The U.S. Daily Value is 600 IU or 15mcg, whereas the (Irish) HSE’s recommendation is 200IU or 5mcg.)

If you’d prefer to chew your intake, as opposed to swallowing a supplement, have a goo at the following:

  • 85 gr/3 ounces of cooked salmon contains just over 400 IU (or 10mcg)
  • 85 gr/3 ounces of drained canned tuna (canned in water) contains c. 150 IU ( 3.75mcg)
  • 2 sardines, canned in oil, contain c. 50 IU (1.25mcg)
  • 1 large egg (yolk-included #obvs) contains c. 40 IU (1mcg)
  • 1 ounce of Swiss cheese contains c. 6 IU (0.15mcg)

In Ireland, vitamin D is recommended for babies across the board, irrespective of whether they are bottle or breastfed. In the UK and the States, it is only recommended for exclusively breast-fed babies, the presumption being the bottle-fed bubs are catered for with their fortified milk formula.


So ‘gwan! Get eating and holiday planning… #JustWhatTheDoctorOrdered!


Assiduously producing Vitamin D in Cuba 2015 #TakeMeBack


As always, let me know if you have any queries and if you’d like to read similar posts, visit


My name is Michelle and I’m a Dublin-based GP (family doctor). Life is short: take the minimalist approach to maximise your health!

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  • Shaun
    March 21, 2017 at 11:26 am

    Hi Michelle
    How or why do the vitamin d recommendations by the bmj vary so much per country ?? Would it be weather related ?

    • Michelle
      March 26, 2017 at 10:27 pm

      Hi Sean,

      Sorry about the late reply! Not weather-related as Ireland and the UK have similar climates… obviously weather would feature in sun-dependant vitamin D production in general though! Thanks, Michelle


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