Popping multivitamins and supplements to stay healthy is fast becoming a national obsession, especially in the depths of winter, when we fret about colds and flu. But Ireland's growing fondness for supplementing our diet is threatening both our wallets and our health, experts say.
Irish consumers spent almost €16m on vitamin and mineral supplements in 2012, according to Euromonitor, which expects our spending to increase 3pc annually over the next five years.
Knocking back supplements, on top of eating food already fortified with vitamins and minerals, can lead people who don't have any vitamin or mineral deficiencies to exceed recommended daily allowances, says Dr Mary Flynn, chief specialist in public health nutrition at the Food Safety Authority of Ireland (FSAI).
"We know there are people out there taking a few food supplements at once, like multivitamins and fish oils, because they see the ads on TV and don't read the small print," Flynn says. "Too many supplements in too many cases -- though not all cases -- can cause harm."
Indeed, academics from Warwick University in the UK and the John Hopkins School of Medicine in Baltimore have now warned people to stay clear of vitamin pills, saying they are a waste of money and may even be harmful if taken by well nourished adults.
One research paper cited in the researchers' report, published in the Annals of Internal Medicine, analysed 24 trials with almost half-a-million participants and found no beneficial effect on mortality from taking vitamins. Another paper examined 6,000 elderly men and found no improvement on cognitive decline after 12 years of taking supplements.
We are conditioned from childhood into believing more is better when it comes to vitamins and minerals, right from reading breakfast-cereal boxes claiming their sugary contents are "vitamin and mineral-enriched". Yet when the European Food Safety Authority scrutinised 44,000 commonly used claims for food products and supplements over five years, just 248 were approved for use.
Since December 2012, a new EU regime requires businesses selling health supplements to provide independent scientific evidence to support claims used in their packaging and marketing.
Richelle Flanagan, president of the Irish Nutrition and Dietetic Institute (INDI), says it has become "ingrained" in us that taking supplements, rather than eating a balanced diet, is a panacea to all our ills.
"People think vitamins are harmless but a lot of research has been done to show they can have a dangerous impact," she says. "For instance, it's been shown that taking high levels of folic acid can mask an undiagnosed B12 deficiency, which is common among older people, and that it can interfere with cancer treatment. I've had cases where pregnant women were taking supplements with vitamin A in them, which can lead to birth defects.
"If people are eating all the foods from the food pyramid, there should be no need to take multivitamin supplements. At clinics, people say they are popping these pills, but when you look at their lifestyle, you find they are not getting their diet right, not exercising, are cutting out meat for some reason, are on some fad diet, or are reaching for a tablet because they are under a lot of stress. When people are under pressure, they want a quick fix."
But not even all the experts agree about what pills you should and shouldn't take.
The public's fascination with vitamins, particularly vitamin C, can be traced back to one man, Linus Pauling, a two-time Nobel Prize-winner. He wrote a book in 1970 claiming high doses of vitamin C could combat not only colds and flu, but cancer, cardiovascular disease, infections and degenerative problems.
He took large quantities of the vitamin himself and helped kick-start an industry devoted to persuading consumers that supplements could revolutionise their health. At least 15 studies have since concluded that vitamin C doesn't prevent the common cold.
Consuming fish oils, found in salmon, trout and tuna, has been touted as reducing the risk of heart disease and even Alzheimer's disease. But a 2013 study in the Journal of the National Cancer Institute, however, found that men with high concentrations of marine-derived omega-3s in their blood had a 43pc higher risk of developing prostate cancer than those with the lowest levels. A separate study revealed that omega-3 supplements did not lower the risk of heart attack, stroke, or death from heart disease or any cause.
"Taking a lot of fish oils can be bad for you as some contain vitamin A, too much of which can be damaging, especially in pregnant women," Flynn says.
She adds the only supplements healthy people need, in certain circumstances, are low doses of vitamin D and folic acid. Other supplements can be used to treat individual conditions, such as iron for anaemia, under the supervision of doctors or dieticians.
All women of childbearing age who are sexually active should take 400 micrograms (mcg) a day to protect against neural tube birth defects, such as spina bifida, even if they are using contraception, Flynn says.
Because there has been an increase in rickets among infants and toddlers in the last five years, the FSAI has been advising that children take 5mcg of vitamin D until they are 12 months old, to help them absorb calcium and build healthy bones and teeth.
There is also a case for the rest of Ireland's population to take the same amount of vitamin D, known as the "sunshine vitamin", between October and March, Flynn says.
While vitamin D is found in oily fish and eggs, it is mainly produced in the body by exposing the skin to sunlight. Because of its northerly latitude, Ireland does not receive enough of the sun rays required to enable sufficient production of vitamin D during the winter months.
"Other countries at northerly latitudes, such as Canada, have vitamin D supplementation programmes and we don't, so we have to play catch-up with that," she says.
"Even if we ate oily fish twice a week, we'd still only get about half of the 10mcg of vitamin D most people need. There are a growing number of foods fortified with vitamin D, so if you are taking a supplement, 5mcg would be enough. That would leave room to get vitamin D from fortified foods such as milk, cheese and yoghurt."
If you are eating right, any other supplements may prove a waste of money. So this year it may be worth making a resolution to ditch the pills and eat your spinach.