The Government has asked NPHET to examine the use of vitamin D in the fight against coronavirus.
Tánaiste Leo Varadkar said he hopes the National Public Health Emergency Team will issue formal advice to be given to the public.
He was responding to Sligo–Leitrim TD Marian Harkin, who raised the issue in the Dáil on Thursday.
She said: "We all know the vaccination roll-out will be somewhat delayed, and we still don't know if the vaccine will prevent transmission of the virus".
She said "all ways and means" should be deployed.
"I've listened to many medics - including Professor Luke O'Neill this morning - when he recognised and supported the role of vitamin D in boosting the immune system".
Speaking on The Pat Kenny Show on Thursday, Prof O'Neill said: "The UK are probably going to mandate vitamin D supplementation... and it makes perfect sense, Pat".
"The criticism always was there hasn't been a double-blind, placebo controlled trial - but we're in the middle of a pandemic for God sake".
"It's a very safe product... and it's cheap as chips".
"The correlation studies are there, which isn't ideal cause it's not double-blind, but still they're very compelling that vitamin D is a protector".
"We know exactly vitamin D really works for the immune system".
In response to Deputy Harkin, Mr Varadkar said: "I know it's been a topic of discussion among the general public and also among healthcare professionals over the past couple of weeks."
"As I think everyone knows in the House, a lot of Irish people are vitamin D deficient - not least because we don't have much exposure to the sun - and that is a situation that is now worse than ever, given that people are unable to travel to the sun [destinations].
"There is evidence of benefit in terms of COVID-19 outcomes, and there's very little evidence of any harm being done should somebody take vitamin D supplements".
'Beneficial in terms of COVID-19'
He quoted several sources of research - including from TILDA, Trinity College Dublin and the Irish Medical Journal.
He added: "The respected Lancet medical journal says that it's uncontroversial to promote it, and there is a chance that it may be beneficial in terms of COVID-19 outcomes.
"Government has asked the NPHET to examine this, and to provide us formal advice which we can then stand over and give to the general public."
The Health Service Executive (HSE) says people do not need vitamin D in their diet every day, because it does not need to be immediately stored for future use.
While the Food Safety Authority of Ireland (FSAI) and the HSE recommend that all babies receive vitamin D supplement during their first year of life.
Vitamin D3 is the preferred form of the supplement for infants.
"Most people should be able to get enough vitamin D by eating a varied and balanced diet and by getting some sun, if that's possible", Mr Varadkar added.
"But if you take vitamin D supplements be careful not to take too much.
"What they say is that taking 25 mcg or less per day is unlikely to cause any harm and may cause some benefit", he explained.
