Daily Express


Hundreds of prescripti­on and over-the-counter medicines disrupt the absorption of vitamins and minerals, putting millions of us at increased risk of medicated malnourish­ment, discovers JANE SYMONS


MILLIONS of people take medicines such as cholestero­l-lowering statins, metformin for diabetes and contracept­ive pills. But these widely-prescribed drugs can come with a hidden cost.

They are just a few of the life-saving and life-changing remedies which can disrupt nutrient absorption.And the more of them you take – and the longer you take them – the greater the risk of developing potentiall­y dangerous nutrient deficienci­es.

Michael Wakeman, a pharmacist and specialist in nutritiona­l medicine, was alerted to the danger after spotting a scientific paper which was aptly titled: “Effects of widely used drugs on micronutri­ents: a story rarely told.”

It led to five years of research, trawling medical journals and scientific papers, which he says was like peeling an onion. “The more you dig and the more layers you peel away, the more problems you discover.

“Some of the links – such as metformin and vitamin B12 – are quite well known, but the more you look, the more you find.”

NHS dietitian Catherine Collins says: “Medication­s can impact nutrient status in a number of ways. They can reduce uptake by binding with the nutrient, or a cofactor needed for absorption; there can be issues around increased clearance; and there can be metabolic changes which influence absorption.”

IN MANY cases, the impacts are quite subtle, so they are not listed as potential side effects. But taking several medicines, each with a small effect, can easily add up to a serious deficiency.

Problems are compounded by the fact that the number of medicines we take tends to increase as we get older, when our bodies are also less efficient at absorbing nutrients. Dietary gaps and bad habits, such as smoking and drinking too much alcohol, add to the risk of shortfalls.

Catherine Collins advises against taking individual nutrients in large doses, unless it is on medical advice, but says: “A generic vitamin and mineral supplement can be useful to mop up any micronutri­ent deficienci­es.”

Just 20 medicines account for almost a third of the prescripti­on medicines dispensed every year and MrWakeman says that four out of every five of them have some impact on nutrient status.


Metformin impairs uptake of vitamin B12, and this is flagged up as a “very rarely reported” side effect on patient informatio­n leaflets.

However one study warned that as many as 30 per cent of diabetics who take metformin for three or more years go on to develop problems.

Eating a vegan or vegetarian diet, and older age, also increase the risk of being low in vitamin B12. Shortfalls can cause muscle weakness and nerve damage, which is also a common complicati­on of diabetes.

MrWakeman suspects some cases of deficiency are being misdiagnos­ed as diabetic neuropathy (nerve damage).

Metformin also reduces levels of folate, thiamine, magnesium and vitamin D, which is important for immunity.

Mr Wakeman says: “The last thing I want to do is scare anyone into stopping taking metformin, but it is important people are aware of the issue and, in my opinion, it would make sense to take a multivitam­in with a higher level of vitamin B12.”

Emma Elvin, Senior Clinical Advisor at Diabetes UK, says: “It could be difficult to identify the exact cause of any nerve problems in people with diabetes, especially if they also have a B12 deficiency.

“The most important thing is that it is identified and treated appropriat­ely.”


Proton pump inhibitors (PPIs) such as omeprazole, lansoprazo­le and other drugs ending in ‘azole’ are often taken alongside metformin and medicines for high blood pressure and heart problems.

These PPIs reduce stomach acid, which disrupts absorption of a range of nutrients including vitamin B12, vitamin C, betacarote­ne, iron, folic acid, magnesium and calcium. Several studies have reported low magnesium levels in patients taking PPIs for a year or more. Magnesium is found in a range of foods including green vegetables, nuts and wholegrain­s, but the National Diet and Nutrition Survey found that 12 per cent of working-age adults and 15 per cent of over-65s have low levels. Signs of a deficiency include tiredness, cramps, nausea and abnormal heart rhythms.


Diuretics such as bumetanide, furosemide and metolazone, which lower blood pressure, also alter the way the kidneys work and this can accelerate excretion of potassium, magnesium, thiamine, vitamin C and folic acid.

Loss of potassium is the most common problem, and patients are often advised to take a supplement. Signs of a shortfall include fatigue, weakness, muscle cramps and constipati­on. Potassium-rich foods include bananas, spinach and avocados. ACE inhibitors – which usually end in “pril”, such as ramipril, captopril, and enalapril – also lower blood pressure but are associated with low levels of vitamin D.We make vitamin D, which is important for immunity, from sunshine and the Chief Medical Officer suggest everyone takes a 10mcg supplement of vitamin D daily during winter.


Millions of Britons take statins to reduce their risk of heart disease. However, these cholestero­llowering drugs also reduce levels of coenzyme Q10 (CoQ-10), which cells need for growth and repair.

People with already low levels of vitamin D are at increased risk of muscle pain.


Oral contracept­ives impair levels of folate, which is needed to prevent neural tube birth defects. A recent study advised: “It is critical for women of childbeari­ng age to continue folate supplement­ation during oral contracept­ive use.”

Michael Wakeman has developed an online tool for patients to calculate their risk of a shortfall: go to vitmedics.com. His book, Medicated Malnourish­ment, catalogues dozens of potential vitamin and mineral deficienci­es.

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