Posted on October 27, 2015 by Kate Halsall

We all know that we need vitamins and minerals in our diet for our health and wellbeing. But what about vitamins and minerals as supplements to assist with our body composition goals or to boost our exercise performance? Unfortunately, just because something is sold as an “energy boost” or aid for “muscle growth”, new research shows that that’s not always the case.

Over the next couple of weeks, I’m going to try and help you make informed choices around supplements by looking at whether they actually do what they say on the tin! This week I’m looking at the well known minerals – potassium and iron.

• Potassium

Have you ever woken in the night clutching your calf and trying not to scream because of cramp? Have you been for a run, cycle or swim and got cramp in your feet? And when you tell people about it they tell you that you’re either dehydrated or that you haven’t had enough potassium?

MYTH – Eat bananas or take potassium supplements because potassium deficiency will cause your muscles to cramp.

FACT – We are not disputing what potassium does in the body: this essential electrolyte helps to stimulate nerves and muscles and maintains fluid amounts in your body. In addition to this, it also helps regulate your heart beat, lower blood pressure and controls the amount of calcium in your bones. It is also accepted that potassium (among other things) is lost during vigorous exercise. However, the general consensus of research in this area suggests that more investigation is needed around cramping, the types of cramp experienced, the conditions in which cramps are initiated and so on. It’s NOT JUST because of dehydration or potassium depletion.

Natural Sources: There are much better sources of potassium than a banana and it’s not just fruit and veg! These include potatoes (normal and sweet), leafy greens, pulses such as white beans and lentils, dates, yoghurt, avocado and fish such as halibut! If you eat a varied healthy diet, you will be having enough potassium.

• Iron

Even as I was researching this, I was presented with adverts in my browser for iron supplements to boost my energy!

MYTH – Iron is essential in energy production and release and can increase in aerobic performance during sports and exercise.

FACT – again we’re not going to dispute the great things that iron does: we know that it helps transport oxygen around the body due to its effects on red blood cells and hemoglobin. In addition to this, it also helps to maintain healthy skin, hair and nails. However research has clearly demonstrated that there is no improvement of aerobic performance through iron supplementation unless the person is iron deficient or suffers from anaemia.

Natural Sources: It is actually very hard not to get iron in your diet! A couple of things to keep in mind is that vegetable sources of iron are not absorbed completely like meat and fish sources. So if you are vegetarian or vegan, it’s best to eat the iron sources with a source of vitamin C (tomatoes, peppers and citrus fruit) to aid the iron absorption. Sources of iron include: meats such as beef and poultry; seafood such as shrimps and tuna; veg such as spinach and sweet potato; whole grains, fruits such as strawberries and watermelon; and also sources of beans such as kidney beans and lentils.

The messages regarding potassium and iron are quite straight forward. We do need them in out diet for our health and well being. The amounts we need will of course vary based on age, gender, health and fitness levels/activity levels. However, as always, if you are healthy and you eat a good, clean and balanced diet, there is no reason that you would need to source these two minerals in a pill or supplement format. If you are going to use supplements, you need to understand why you need them and what they are REALLY doing for you.