Last week I wrote about what we know when it comes to magnesium supplements and whether they may help lower your blood pressure. Another common supplement that people take is potassium and this has been claimed to lower blood pressure. Sometimes this is taken as a stand-alone supplement, or it may be used as a substitute for normal table salt. So… does it work?
It will come as no surprise to hear that the official guidance for us doctors in the UK is not to recommend potassium supplements to help lower blood pressure. We just don’t seem to get on with supplements do we? But why is this the official line? I’ll dig a bit deeper…
Firstly, I’d say that the studies that have been done looking at potassium and blood pressure are more confusing than the magnesium ones. This is because there are some studies that have appeared to show a significant improvement in blood pressure when people take potassium supplements. BUT, there are other, equally well designed studies that haven’t. We have no idea why there is this variation in results. Different doses of potassium were used but there is no obvious link between dose and effect. And although the study designs aren’t perfect, they aren’t too bad either so that isn’t an obvious reason.
My suspicion is that this variation is because there is some reason which we don’t know yet that explains why some people may benefit from potassium supplements, while others do not.
Different results for different people
For example, there was one study in Kenya that showed a massive improvement in blood pressure readings when people took potassium supplements. We do know that one of the systems in our body that regulates blood pressure is slightly different in black people. So this could be a factor in explaining the variable results, but it needs repeating and studying further.
Another suggestion has been that people who are already eating a high sodium diet (that’s normal table salt) may benefit more from potassium supplements. Something else that influences how beneficial potassium appears to be is how long you monitor the effect for. If you include studies in the analysis that only looked at the benefit for less than 8 weeks it generally appears better than those that looked at it over a longer time. So maybe whatever benefit there is only works for a short while?
Are potassium supplements safe?
The good news is that, just like with magnesium supplements, the studies reported no more side effects from potassium supplements than with placebo. However, potassium supplements can be dangerous if taken with some blood pressure medications (mostly ACE inhibitors and Angiotensin 2 Receptor Blockers) so if you do decide to try them it is important to check with your doctor or pharmacist first.
So, hopefully it now makes sense why doctors aren’t able to recommend potassium supplements to help lower blood pressure. We just don’t know enough to be able to tell you if they work.