Australia offers one of the clearest official snapshots. According to the Australian Bureau of Statistics, 33.6% of people aged two and over – around 8.5 million people – took a dietary supplement in 2023, up from 28.5% in 2011–12.
The trend is not confined to Western countries either. A Japanese study published in 2026, based on a 2024 survey of adults with a history of buying major supplement products, found that 18.5% were taking supplements above the manufacturer’s recommended daily intake.
The industry behind this habit is vast. Reuters cited market projections putting global supplement sales at $192.7bn in 2024, rising to $414.5bn by 2033. But supplements are not medicines. In the EU, they are regulated as foods, and the European Food Safety Authority describes them as concentrated sources of nutrients or other substances with a nutritional or physiological effect. That distinction matters: they can be marketed for health, energy and performance, while consumers may assume a degree of medical testing and control that does not necessarily exist.
The risks are not theoretical. A study by US health authorities and the Food and Drug Administration estimated that adverse events linked to dietary supplements account for about 23,000 emergency department visits and more than 2,000 hospitalizations in the United States each year. In 2023, the European Food Safety Authority lowered the tolerable upper intake level for vitamin B6 for adults to 12 milligrams per day after reviewing evidence linking excessive intake to peripheral nerve damage.
When Supplements Make Sense
Despite the marketing surrounding supplements, experts are far more selective about who should take them. Ondrej Sukel, president of the Slovak Chamber of Pharmacists, told Statement that no comprehensive data on supplement use in Slovakia is available. At best, individual surveys can provide a general picture.
For example, a 2023 poll conducted by Instant Research for Natures found that respondents most commonly take vitamins C and D, along with zinc, to boost their immunity.
Social media and online retailers are awash with promises of better health, clearer skin and improved performance. Experts, however, agree that healthy people can get all the vitamins and minerals they need from a balanced diet.
“Dietary supplements have their place in cases of proven deficiency or for specific population groups, but not as a universal means of disease prevention. The scientific evidence is consistent in this regard”, the pharmacist says.
General practitioner Rastislav Zanovit notes these specific groups include pregnant women, who are advised to take folic acid, seniors and vegans with vitamin B12 deficiency, as well as people with a medically confirmed deficiency of specific nutrients.
What Else Is Important
According to experts, even some of today's most popular supplements, including magnesium, have little clinical significance.
“Another unproven trend is vitamin infusions offered by various ‘wellness clinics’ with the promise of improved immunity, increased energy or detoxification”, says Sukel.
The same applies to electrolytes, he adds. They have become increasingly popular among recreational athletes, but not everyone who exercises or sweats more than usual necessarily needs them.
“Most healthy people can easily replace mineral losses from normal physical activity or summer heat with a varied diet and drinking water. Electrolyte drinks have their place, especially in cases of significant fluid loss”, Sukel explains.
Duplicate Dosing
Experts say the biggest problem is that people often combine multiple supplements without realizing they contain the same vitamins or minerals. Many follow the assumption that more is always better.
However, vitamins are not harmless simply because they are vitamins. Taken in excessive amounts, they can have adverse health effects just like medications. Both are biologically active substances. Sukel points to vitamin B6 as one example: excessive long-term intake has been linked to peripheral nerve damage.
Warning signs are emerging elsewhere as well.
“For example, long-term use of high doses of vitamin A is risky, as it can damage the liver and is also unsuitable during pregnancy. An excess of vitamin D can lead to elevated calcium levels in the blood and, consequently, kidney damage”, explains Zanovit.
“Vitamin E, in high doses, can increase the risk of bleeding. Furthermore, beta-carotene supplementation has been shown to increase the risk of lung cancer in smokers”, adds Sukel.
Minerals are not risk-free either. Excessive iron intake can damage the liver and digestive tract, while unnecessary calcium supplementation can increase the risk of kidney stones in susceptible individuals.
To avoid overdosing, consumers should not rely solely on a product’s name, but should also check the ingredient list. Experts also advise against relying on unqualified online influencers or advisers who are paid to promote supplements on social media.
Before a drug is marketed, it must demonstrate efficacy, safety and quality, Sukel says. Dietary supplements are different: while manufacturers must ensure their safety and proper labeling, they generally do not have to prove that the claimed effect will actually occur. “Consumers should therefore be cautious about marketing claims promising a wide range of effects”, he warns.
What to Combine With What
Above all, the morning ritual of emptying a daily pill organizer into one’s hand and swallowing everything at once is best avoided. To maximize their effectiveness, supplements should be taken in the right combinations and at the appropriate time, whether on an empty stomach, with food or several hours apart.
For example, the fat-soluble vitamins A, D, E and K are recommended to be taken with a meal that contains fat.
Iron is absorbed more efficiently when taken with vitamin C. However, dairy products, calcium, magnesium, zinc, tea and coffee should be consumed at least two hours before or after an iron supplement, as they interfere with iron absorption.
Taking calcium, magnesium and zinc together can reduce the absorption of all three minerals.
“It’s also important to separate certain supplements from medications – for example, iron or calcium can reduce the absorption of antibiotics or thyroid hormones”, Zanovit explains.
The B vitamins and vitamin C are water-soluble and are best taken in the morning on an empty stomach with a glass of water, as they support energy production and help with concentration. Magnesium and some forms of calcium, by contrast, are generally better suited to the evening because they promote relaxation and recovery.
When antibiotics are prescribed, probiotics are generally best taken several hours later.
Medication Interactions
Zanovit also advises anyone taking dietary supplements to inform their doctor. Many patients do not consider this important, but it can have a significant impact on their medical treatment.
“For example, St. John’s wort reduces the effectiveness of several medications, including hormonal birth control, certain antidepressants and heart medications. Ginkgo biloba, garlic or omega-3 fatty acids in higher doses can increase the risk of bleeding in patients taking blood thinners”, he explains.
High doses of vitamin B7 can also distort the results of certain laboratory tests, including thyroid function and tests for cardiac biomarkers.
People taking creatine should also exercise caution. The popular sports supplement raises blood creatinine levels, one of the main indicators of kidney function. As a result, it should be discontinued at least one week before routine blood tests or kidney function tests.
