Is there something fishy about food supplements, or are they a good dietary aid?
As new research shows omega-3 capsules do nothing for heart health, Katie Byrne talks to experts to find out the case for and against dietary aids
There was a time when the Irish approach to dietary supplements amounted to little more than a spoonful of cod liver oil and a multivitamin for those who were feeling fancy.
In the last 10 years, however, the industry has exploded with a proliferation of high-street health shops and a staggering array of products on the shelves.
According to the Food Safety Authority of Ireland (FSAI), the number of health supplements on the Irish market has risen from 700 in 2007 to over 2,500 in 2017 - an increase of over 300pc.
But are these supplements really enhancing our wellness, or are they relying entirely on the placebo effect to work?
That's the question being asked after a study on the effects of omega-3 (better known as fish oils) put the supplement industry under the spotlight once again.
Cochrane, an independent organisation that evaluates existing medical research, investigated the popular belief that long-chain omega-3 supplements protect the heart.
The researchers reviewed trials that involved more than 112,000 people and concluded that this popular supplement offers no protection against heart attacks or stroke.
"Researchers have spent a lot of money over the years researching this topic to try and find single nutrients that result in positive effects," explains Dublin-based dietician Orla Walsh. "What research is now suggesting is that this is a complex area that is unlikely to be managed with any single nutrient of the diet.
"Instead, research suggests that all the nutrients of interest, such as omega-3, may be more impactful when eaten in the natural form and that the overall balance of the diet, as well as the dietary patterns, have the greatest impact."
Walsh points to the dietary guidelines for preventing heart disease, which encourage people to eat two portions of fish each week, one of which should be an oily fish.
"This advice doesn't change," she adds. "What this study suggests is that we should stop looking for a magic pill, or expect that taking a nutrient out of the food and consuming it in tablet form will have the same beneficial effect as eating the nutrient naturally within the food."
This latest research on the effects of supplements proves that it's better - and possibly even cheaper - to eat some mackerel once a week if you want to keep your ticker happy. (Boots' own-brand omega-3 fish oils cost approximately €1.60 a week, whereas Aldi's mackerel fillets cost approximately €1.25 per serving).
However, it's worth noting that not everyone takes omega-3 supplements for heart health. Some take it for better brain functioning; others swear by it for plumper, clearer, more radiant skin.
Dr Fionnula McHale, a qualified medical doctor specialising in functional medicine, takes fish oils every day, along with B-Complex, co-Q10 and glycine and magnesium in the evenings.
It's more than the average doctor might take, but McHale isn't your average doctor. Functional medicine combines mainstream medicine with alternative and complementary medicine, so it's no surprise that she is more open to dietary supplementation - and more aware of the risks. "I have no problem with regulation on supplements because they do exert an effect and, for some people, they are no different to taking a medication on a high dose," she says.
McHale prescribes a number of different supplements to her patients but she stresses that it's "context-dependent" and always requires diagnostics.
The problem, however, is that the vast majority of people don't consult with an expert before they walk into a health shop. They consult with Dr Google.
GP Dr Brian Higgins has encountered this type of patient time and time again at his practice in Galway.
"When people get fatigued, the first thing they do is self-diagnose with B12 deficiency and look for a B12 injection," he says. "But unless you have pernicious anaemia, there is absolutely no evidence behind it. It's a massive placebo effect.
"I've had patients who have done quite a bit of research themselves and matched up their symptoms -yet their blood results show that they are not B12 deficient. Clinically, they could actually be depressed, but they become fixated on wanting this injection."
Trendy intravenous vitamin infusions are another bugbear for Dr Higgins, who points out that they are based on the Myers' cocktail, a nutrient mixture invented by physician John Myers for the treatment of malnourished alcoholics. A hangover isn't quite the same thing…
For most people, an intravenous vitamin infusion will have no effect whatsoever.
"The body has a really tight homoeostasis - or balance of vitamins - in the blood," explains Dr Higgins. "If you take too many, it generally just gets excreted. Iron is excreted in the stool and that's why if you get too much iron, you get constipated."
However, self-diagnoses can have harmful side-effects too. Dr Higgins brings up hypervitaminosis, which is what happens when abnormally high levels of vitamins in the blood lead to toxic symptoms. Vitamin D toxicity can cause kidney problems; calcium toxicity can lead to overactive parathyroid glands and vitamin A toxicity in women can lead to congenital birth defects.
Amino acid supplementation can also be problematic, says Dr McHale. "People sometimes take them to manage depression and anxiety, the classic example being tryptophan, which people take as a precursor to serotonin.
"The thing is, if you don't take that with a B-complex, antioxidant support or zinc to utilise it efficiently, you're going to offset the balance of dopamine, which is the yin to the yang of serotonin in the brain."
The Food Safety Authority of Ireland (FSAI) recently launched guidelines that highlight the detrimental effects of over-consuming certain vitamins and minerals, but it's also worth noting they recommend folic acid for women who are sexually active and vitamin D supplements for infants from birth to 12 months.
Irish adults are also at risk of vitamin D deficiency. According to recent research from the Irish Longitudinal Study on Ageing (TILDA), one in four adults over the age of 50 are deficient in the sunshine vitamin during winter.
And while we should all endeavour to get the nutrients we need from a balanced diet, we can overlook the deficiencies that occur alongside certain lifestyle choices and medications.
McHale points out that the contraceptive pill can deplete B vitamins and vegan nutritionist Rosanna Davison says people who eat a plant-based diet are often deficient in Vitamin B12.
Davison, for her own part, takes vitamins B12, D3, and an algae-based omega-3 supplement. She also takes probiotics, and adds in vitamin C and zinc at certain times of the year or if she's feeling run down.
"If you eat a well-planned diet based on whole, fresh foods, then you should receive much of what you need from that," she adds. "Supplements have their place but they can't substitute a varied diet and real food must always come first."
Dr Higgins is in agreement. "The thing about vitamins is that they are definitely beneficial, and you definitely need them in your diet, but there is a benefit curve. You only need them to the level you need them, and any more than that can be of no benefit whatsoever or occasionally harmful."