Most healthy people do not need supplements, although many turn to them as a quick fix for poor eating habits.
This is not necessarily a bad thing, say the experts. Even so, they warn that frequent pill-popping can have negative side effects.
These include kidney or liver problems, vomiting and diarrhoea.
Despite that, supplements are flying off the shelves more than before.
Market research firm Euromonitor said in a November report that Singaporeans are spending more on vitamins and health supplements.
Consumers here forked out US$374.4 million (S$494 million) on these products last year, it found. This was US$30 million more than what was spent in 2012.
Popular products include probiotics, fish oil, glucosamine for joints, and co-enzyme Q10, which is said to help lower one's cholesterol levels.
The firm attributed this trend to Singaporeans' busy urban lifestyles, which can leave little room for regular exercise and a balanced diet.
"Many Singaporeans do not have time to stay physically active, and often indulge in meals that are unbalanced in terms of nutrition," said Ms Yvonne Wong, a research analyst at Euromonitor International.
"This therefore spurs them to purchase vitamins and dietary supplements to obtain the necessary nutrients."
The habit of eating out frequently is also another issue. Six in 10 Singaporeans eat out at least four times a week, according to the 2010 National Nutrition Survey.
But such foods tend to be less nutritious.
"Hawker meals tend to be high in refined carbohydrates and low in vegetables," said Ms Mah Wai Yee, a principal dietitian at Farrer Park Hospital. "We also tend not to have fruits with our meals."
TOO MUCH OF A GOOD THING?
For those with such nutritional holes to plug, vitamins and supplements are an easy solution. But too much can be bad for you.
This is especially the case with fat-soluble vitamins, say the experts, including vitamins A, D, E and K. As the name suggests, these dissolve in fats and therefore take a longer time to pass out of the body.
"For example, taking too many vitamin D supplements over a long period of time can cause too much calcium to build up in the body," Ms Mah said. "This can weaken the bones and damage the kidneys and the heart."
But she added that it is also possible to overdose on certain water-soluble vitamins, such as vitamin B6.
Too much of this vitamin can lead to nerve problems that cause pain and numbness in the hands and feet.
More in Singapore popping vitamins, supplements
People with pre-existing health conditions should be careful when taking stimulant drinks, such as Red Bull or 5-Hour Energy shots.
They often contain caffeine, which can be risky for people with heart problems, for example.
"The stimulants can potentially worsen anxiety in anxious patients," pointed out Dr Derek Koh, who heads Thomson Wellth Clinic @ Novena.
"They may not be good for patients with underlying heart diseases, as they would cause palpitations."
When it comes to buying off-the-shelf supplements, senior pharmacist Serena Kon advises caution, as these products are not regulated by the Health Sciences Authority.
"Individuals need to be mindful to purchase their supplements from trusted sources and be vigilant in evaluating claims made by supplement vendors," said Ms Kon, who works at the Singapore General Hospital.
As a general rule, many factors affect how long it takes for a supplement's benefits to kick in, added Ms Kon.
In one research paper published in 2005, scientists studied people taking 1,500mg of oral glucosamine every day. The supplement is supposed to help with joint health.
They found that it took at least two weeks to reduce joint pain and increase a person's mobility.
Said Ms Kon: "Patients have to be aware that very few natural supplements have been vigorously studied in clinical trials, and that evidence for the use of natural supplements is not as robust compared to prescription medicines."
Added Dr Derek Li, a family physician at Raffles Medical: "In many cases, we may never see any difference as we are not deficient in anything."
While most reputable supplements are "very safe" for consumption, Dr Li said, those with chronic health problems or allergies should pay extra attention to what they are eating.
"A good example is glucosamine... which is usually derived from shellfish products," he said. "Therefore, people with shellfish allergies should avoid such supplements."
If a healthy person plans his meals carefully and gets regular exercise, he might not need supplements at all, said Dr Li.
He added that one possible exception could be vitamin D, which is normally obtained through exposure to sunlight.
"One might expect that this should not be a problem living in Singapore," he said.
"But I have come across patients who see very little sunshine due to the nature of their jobs, and hence develop vitamin D insufficiency over time."
Source: The Straits Times © Singapore Press Holdings Limited. Reproduced with permission.