After a few weeks of feeling increasingly nauseous, I went to the GP for some blood tests. The next day, they called with frightening news: I had high calcium levels.

Elevated calcium can be dangerous. It can signify health problems such as parathyroid issues, and, if untreated, may cause even more, such as kidney stones and issues with bones, the heart and the brain.

Thankfully, in my case, the explanation was simple. You see, in addition to the multitude of supplements already on my desk – omega 3, collagen, probiotics, magnesium, a B vitamin complex – I had been taking a daily high-dose calcium tablet for a few months in the hope of boosting my bone density.

After that call from the GP, I stopped taking the calcium, the nausea and kidney pain subsided and, a week later, a second blood test came back normal.

As a health writer, I am slightly ashamed. But, like millions of others, I’d fallen prey to the latest health trend.

There are two especially alarming supplement-related fads. ‘Vitamin maxxing’ is a social media trend encouraging people to take large doses of supplements in pursuit of optimal health – as with me and my calcium.

Then there’s ‘supplement stacking’, where they are consumed in a specific combination to improve immunity, gut health, sleep, energy and ageing.

According to a Which? survey, three quarters of UK adults take supplements and around one in six of us take four or more a day.

Alice Smellie had been taking a daily high-dose calcium tablet for a few months in the hope of boosting her bone density but found out she had elevated calcium levels

We are bombarded by influencers explaining why taking a handful of pills is a smart thing to do, but respected industry voices are increasingly concerned about the safety of taking masses of supplements or high doses of them.

‘Many supplement stacks are based on social media trends, influencer recommendations or anecdotal reports rather than robust clinical evidence,’ says Dr Emma Derbyshire, a public health nutritionist from the Health and Food Supplements Information Service (hsis.org).

She said there was a risk such sources ‘oversimplify nutrition’ by suggesting more vitamins ‘automatically equate to greater health’.

My situation was slightly complex but hardly unique. Following cancer treatment in 2023, I had infusions called zoledronic acid (bisphosphonates) to boost bone density. After each infusion I was prescribed calcium for a month.

As I also have a family history of osteoporosis, I bought my own calcium to take after that supply ran out. I was doing my best to improve my bone health.

In fact, tests revealed that my calcium level is naturally high and by upping my intake I had pushed it up too much.

I wasn’t even taking super high levels. The NHS says adults need 700mg of calcium a day and doesn’t recommend taking more than 1500mg. As my supplement was 1000mg, I was within the limits, but as I already had high levels, it made me very unwell.

And too much of anything can be dangerous. ‘Excessive vitamin A intake has been linked to liver toxicity and an increased risk of fractures, while chronic high doses of vitamin B6 can lead to nerve damage,’ says Dr Megan Rossi (theguthealthdoctor.com).

There can be negative interactions between supplements as well as between supplements and medications. ‘One client complained of bloating, digestive discomfort and nausea,’ says Emma Bardwell, nutritionist and author of The 30g Plan Cookbook.

‘We reviewed her supplement stack and she was taking a multivitamin, a greens powder, magnesium, a hair and nail supplement, collagen, a probiotic and several random wellness powders she’d discovered through social media.’ After getting rid of most of the supplements, her issues resolved.

Bardwell says this is by no means uncommon. ‘I’ve seen people unknowingly double or triple up on the same ingredients by taking a multivitamin alongside individual supplements, powders and wellness products,’ she says. ‘It’s vital to check how much you’re consuming.’

A further problem is that many neglect diet in favour of massive doses of vitamins. ‘I call this the “health halo” effect,’ says Dr Rossi. ‘People become so focused on finding the perfect supplement stack they overlook lifestyle habits, such as eating a diverse, fibre-rich diet, exercising regularly, getting enough sleep and managing stress. This will have a far greater impact on long-term health than adding another capsule.’

So, what’s the solution? In May, I attended the Oxford Longevity Project summit. Speakers overwhelmingly were in favour of lifestyle factors such as an unprocessed food diet, exercise, sleep, stress management and social relationships. Not one of the eminent professors or scientists suggested indiscriminate use of high dose supplements is a good idea.

But they said that there’s a place for evidence-based supplementation. Dr Derbyshire points out that we are a nation struggling with vitamin and mineral deficiencies.

A report by HSIS, which represents health-food manufacturers, showed we have significant shortfalls in vital nutrients such as Vitamin D, calcium, iron, potassium, selenium and Omega-3 fatty acids.

‘To help bridge these gaps, a multivitamin and multi-mineral supplement is a useful nutritional safety net alongside a balanced diet,’ she suggests. But that’s just one a day, not ten a day.

Bardwell emphasises that supplements are – obviously – just supplements, and that our diet should provide most nutrients.

Now I just take vitamin D and collagen. I focus far more on diet: fibre, lean protein and a wide range of fruit and veg, and strength training three times a week to maintain bone density.

It turns out the secret to feeling better and maximising my health wasn’t at the bottom of a pot.