Is your medication making you sick?
Hundreds of prescription and over-the-counter drugs disrupt the absorption of vitamins and minerals, putting millions of us at 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 medicines 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 micro nutrients: 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 impact nutrient status in a number of ways. They reduce uptake by binding with the nutrient, or a co-factor needed for absorption; there can be issues with increased clearance; and there can be metabolic changes influencing 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 less efficient at absorbing nutrients. Dietary gaps and bad habits, such as smoking and drinking alcohol, add to the risk of shortfalls.
Catherine Collins says not to take nutrients in large doses, unless it is on medical advice, but adds: “A generic vitamin and mineral supplement can be useful to mop up micronutrient deficiencies.”
Just 20 medicines account for almost a third of prescriptions dispensed each year and Mr Wakeman says four out of five of them have some impact on nutrient status.
DIABETES DANGER Metformin impairs uptake of vitamin B12, and this is flagged up as a “very rarely reported” side effect on information leaflets. However, one study warned as many as 30% of diabetics taking metformin for three or more years 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. Mr Wakeman suspects some cases of deficiency are being misdiagnosed as diabetic neuropathy. 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
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In many cases the impacts are subtle, so they aren’t listed as potential side effects
opinion, it would make sense to take a multivitamin with a higher level of vitamin B12.” Emma Elvin, senior clinical adviser at Diabetes UK, says: “It could be difficult to identify the exact cause of any nerve problems in people with diabetes, especially if they have a B12 deficiency too. The most important thing is that it is identified and treated appropriately.”
ACID-REGULATING MEDICINES
Proton pump inhibitors such as omeprazole, lansoprazole and other drugs ending in “azole” are often taken alongside metformin and medicines for high blood pressure and heart problems. They are also sold over the counter as Nexium or Guardium.
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% of working-age adults and 15% of over-65s have low levels.
Signs of a deficiency include tiredness, cramps, nausea and abnormal heart rhythms.
BLOOD PRESSURE PITFALLS
Diuretics such as bumetanide, furosemide and metolazone 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 – are associated with low levels of vitamin D. We make vitamin D, which is important for immunity, from sunshine and shortfalls are common. The Chief Medical Officers suggest everyone takes a 10mcg supplement of vitamin D in winter.
STATIN STATUS
Millions of Britons take statins to reduce their risk of heart disease. However, these cholesterol-lowering drugs also reduce absorption of coenzyme Q10, which cells need for growth and repair.
The impact of statins on vitamin D varies, but there is evidence that people with already low levels are at increased risk of muscle pain – a known side-effect of these drugs.
PILL PROBLEMS
Oral contraceptives impair levels of folate, which is needed to prevent neural tube birth defects. A recent meta-analysis advised: “Because of the reduction in blood folate concentrations associated with the use of oral contraceptives, 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.