There’s one thing those who take a certain supplement should keep in mind, according to Dr Karan Rajan.
15:31, 05 May 2025Updated 15:37, 05 May 2025
People who take this supplement should be aware of one crucial thing, says the doctor(Image: Getty Images)
Millions of people in the UK take supplements. Whether for a vitamin deficiency or as a food replacement, a huge proportion of the population take prescribed or store-bought supplements every day. But a doctor has issued a stark warning to anyone who takes one type of supplement in particular.
Dr Karan Rajan can often be found on TikTok, sharing advice and spreading his medical knowledge. Boasting over five million followers on the social media platform, the doctor is a well-trusted source of health advice for many.
A video on his TikTok page warns anyone who takes iron supplements of one thing that can prevent them from working. The doctor said: “Most people don’t know this, including a few doctors.”
Millions of people in the UK take iron supplements, according to Imperial College London.
But Dr Rajan has warned all of these people of something that can hinder how well these supplements work.
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He said: “There is one very important thing you need to know if you’re prescribed iron supplements which can impact your treatment and how you absorb it.
“If you consume too much calcium, either in supplement form or in food, this can actually impact iron absorption.
“And if your dietary iron is already low, this could lead to a deficiency.”
The doctor explains how calcium competes with iron for absorption in your intestines.
Calcium can hinder how well our bodies absorb iron, said the doctor(Image: Denise Bush via Getty Images)
High levels of calcium in your body can also have an impact on your body’s ability to absorb non-heme iron, which the health expert explains is the kind of iron you get from plant-based foods.
Dr Rajan continues: “That’s why many people recommend taking iron supplements with a source of vitamin C to improve absorption.”
Indeed, a study from the National Institutes of Health explained that vitamin C is the only dietary constituent other than animal tissue that has been shown to promote iron absorption.
Dr Karan Rajan continued by explaining the particular types of calcium that can hinder how well our bodies absorb iron.
He said: “Calcium salts like calcium carbonate, which is commonly found in heartburn and indigestion remedies, are alkaline which can hinder iron absorption.”
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If you do usually take both calcium and iron supplements, the doctor recommends taking them at different times of day, a few hours apart.
Studies have shown that taking both iron and calcium supplements together, particularly with a meal, can decrease the absorption of the iron into your body.
The doctor said: “If you’re drinking milk, eating yoghurt, or consuming any calcium-rich food, consider delaying your iron supplements by a few hours.
“If you’re being treated for iron deficiency anaemia, it’s worth flagging to your doctor, if they’re not already doing it, that you want to regularly check your calcium levels.”