Everything You Need To Know About Supplements, Part 1: Magnesium

This alien looking lump of crystals is vital to life

This alien looking lump of crystals is vital to life

This is the first part (of I don't know how many) of a series of blog posts on supplements. It's a topic that used to fascinate me so much when I started personal training that I would spend hours upon hours reading about them. Over the years, I realised that many supplements are hugely over-hyped and often a waste of money. 

In this series of blog posts I'll delve into the research on certain supplements that I believe are worth your hard-earned money. If there's no blog post on a supplement in this series once it's finished, it's either because I haven't heard of it or it's a waste of time and money with no significant benefits to be gained by taking it. 

Let's get cracking.

Magnesium's role in the body

This article states a dizzying list of several complex biological processes that just cannot happen without magnesium; it is a mineral that is essential to life. The true list of things affected by magnesium and impaired when intake is low is probably too long to list, I'd bet that there are more than 300 processes that are actually reliant on it!

Some of things most relevant to the people I coach are its effects on blood pressure, insulin sensitivity and aerobic exercise. 

High blood pressure is often called the "silent killer", as it increases the risk of things such as heart attacks, strokes and heart disease. Magnesium can be one important part of helping bring blood pressure down. Examine.com has a nice summary of the research on their brilliant page on magnesium:

There appears to be a significant reduction in blood pressure assuming one of two conditions is met, either the subject is low in magnesium levels in the body (deficient) or if the subject has elevated blood pressure (140/90 or above), with the latter not requiring a deficiency to precede the blood pressure reducing effects

Interestingly, a meta-analysis gives us an idea of how much magnesium can lower blood pressure by. The authors looked at 34 studies where the average dose of magnesium was 368mg per day and concluded that a "2.00/1.78 mm Hg reduction in systolic/diastolic BP". For someone struggling with high blood pressure, these numbers might be a bit disappointing. However, this is a small and inexpensive change to make that could be a part of a bigger plan for anyone wanting to manage high blood pressure. The first port of call for anyone with high blood pressure should always be their doctor, and it's worth running the idea of magnesium supplements past them.

Next up is the topic of insulin sensitivity. Examine define insulin sensitivity as:

Insulin sensitivity is the relationship between how much insulin needs to be produced in order to deposit a certain amount of glucose. You are insulin sensitive if a small amount of insulin needs to be secreted to deposit a certain amount of glucose, and insulin resistant if a lot of insulin needs to be secreted to deposit the same amount of glucose. Insulin sensitivity is seen as good as the opposite, insulin resistance, is a major risk factor for the development of Type II diabetes.

Interesting stuff. Insulin resistance is brought on by a variety of factors and seems to be part of a myriad of conditions that make up metabolic syndrome. This is usually, but not always, closely related to excess body fat which is due to poor nutrition and lack of exercise. Someone getting a diet full of processed foods and is gaining weight is likely to not be getting enough of the kind of whole foods that supply us with magnesium.

When people who have poor insulin sensitivity supplement with magnesium, insulin sensitivity can improve. This is perhaps due to an improvement in pancreatic function that is thanks to increased magnesium intake. 

The complexity of the body never ceases to amaze me. The two topics we've briefly looked at above are just two of many things that magnesium supplementation can help some people with. Another, amazing potential use for it is in aiding performance in hard aerobic training. There has only been one study on this subject to date, but it showed that triathletes taking magnesium orotate had a remarkable improvement in a test that was similar in demand to a triathlon. 

Dietary intake of magnesium

The daily recommended intake of magnesium is around 300mg for women and 400mg for men according to the first link in this article. This can be taken in from only food sources, but a lot of people in the Western world will not be getting this RDA due to a diet high in processed food and grains, meaning that deficiency is likely fairly widespread. Interestingly, and also frighteningly, the magnesium content of the soil a lot of our food is grown in is rapidly becoming depleted of magnesium as well. This means it's likely that our food is also less rich in magnesium compared to 50 years ago. 

There are several foods that are still rich in magnesium and they are all foods that have other benefits as well. 

  • Leafy greens
  • Nuts and seeds
  • Legumes 
  • Fish
  • Oats
  • Buckwheat
  • Dairy products

Getting a mix of foods such as these is a good strategy to getting your intake up to somewhere around the RDA.


If your intake still falls below the RDA a supplement may be a good idea. There are several different forms of magnesium supplements on the market, some are good and some are garbage. 

The most common and cheapest supplemental form of magnesium is also, unfortunately, the worst. It's called magnesium oxide: when you see a supplement contains this as its main or only source of the mineral, steer clear and look for a higher quality one. This study shows that magnesium oxide is poorly absorbed, and that magnesium citrate (another cheaply available form) is a better bet, with significantly higher levels of absorption. However, some people might find that for them magnesium citrate is a potent laxative - this is one of its uses in clinical settings. This is something that varies from person to person, so it's a good idea to start the dose low and increase if there are no side effects. 

Other supplements worth trying are the widely available and reasonably priced magnesium glycinate (or sometimes labelled diglycinate or bisglycinate) and the slightly more pricey magnesium orotate, which seems to have extra benefits for heart and brain health. 

If you want to experiment with supplements I highly recommend you discuss it with your doctor, especially if you have a pre-existing health condition that you think it might improve.

I hope this post has been useful to you.