Quick Summary tl;dr
For many people on a low carbohydrate or ketogenic diet, low magnesium status can be common. First, ensure that you are getting as much of your magnesium sources from your food as you can. If you are still experiencing side effects, then supplementing would be recommended.
With magnesium being the fourth most abundant mineral in the body, it plays a wide role in many important processes. Over the past century though, there has been a significant decrease in magnesium intake ( 1).
The recommended nutrient intake per day for magnesium is between 300-400 mg/day (2).
As discussed in this previous article, those following a low carbohydrate diet can experience transient drops in the level of magnesium in the body. This loss of magnesium is what can result in "keto-flu" symptoms including: headaches, cramps, heart arrhythmias and low blood pressure.
Although there is an abundance of low carbohydrate foods that are high in magnesium, some people will still need to get a little extra help reaching the RDA.
Knowing When to Supplement
If after a couple of weeks on a low carbohydrate diet, you find that you are still experiencing muscle cramps or soreness as well as any heart arrhythmia’s (often described as a heart flutter), then these can be the signs that your body is still lacking in magnesium. This can be especially true if you exercise a lot.
Which Supplements to Choose?
Minerals such as magnesium must be combined with another molecule to make it stabilised for supplementation. There exists a range of magnesium supplements all with varying absorption, bioavailability and therapeutic inputs within the body.
This makes some supplements better for the body than others. Below is an overview of which magnesium supplements to choose and which to try and avoid.
Good Sources of Magnesium Supplements: Use
Magnesium is bound to glycinate which is a non-essential amino acid. This is one of the most bio-available form of magnesium meaning it is better absorbed by the body. Unlike other magnesium supplements it also does not cause gastrointestinal problems including diarrhoea ( 3).
Due to the calming nature of glycinate, this supplement has specifically been shown to help decrease muscle pain (4). As well as helping with specific fatigue illnesses including fibromyalgia ( 5) and chronic fatigue syndrome ( 6).
Martina @ KetoDiet: Example products - Doctor's Best or Pure Micronutrients Magnesium Glycinate (Amazon affiliate links)
This is one of the most common forms of magnesium supplements available. Magnesium citrate has good bioavailability particularly in relation to magnesium oxide ( 7). It is also a lot cheaper than the glycinate form.
Since citric acid is a mild laxative, this type of magnesium supplement can cause a loosening of stools ( 8). Therefore, this form of supplement would be suitable for those who may be experiencing constipation whilst on their low carbohydrate diet.
Martina @ KetoDiet: Example product - Calm (Amazon affiliate link)
Magnesium chloride is often used in over the counter medications for digestive disorders such as GORD ( 9). The chloride bound to the magnesium can help to produce more hydrochloric acid (HCL) in the stomach.
This type of supplement is better suited for those who are suffering from digestive issues, especially involving low acid production.
Martina @ KetoDiet: Example products - Slow-Mag Magnesium Chloride tablets, Pure Zechstein Magnesium Chloride Bath Flakes or ReMag Pico-Ionic Liquid Magnesium (Amazon affiliate links)
This form of magnesium supplement is paired with malic acid. Whilst it is commonly found in fruits, malic acid in an integral molecule involved in the Krebs cycle. This is where most of your energy is generated for the body to function. Many studies have looked at the use of magnesium malate in fatigue syndromes such as fibromyalgia and chronic fatigue syndrome ( 10, 11).
Magnesium malate would therefore be of benefit to people who are experiencing symptoms of extreme fatigue.
Martina @ KetoDiet: Example product - Source Naturals Magnesium Malate (Amazon affiliate link)
Both magnesium and the amino acid Taurine, have been shown to help with cardiovascular health ( 12).
Taurine itself is a very calming amino acid and L-Taurine is available as a nootropic compound which has been shown to help improve cognition and memory. For this reason, people believe that magnesium taurate is the better form of magnesium supplement for brain health.
Martina @ KetoDiet: Example product - Cardiovascular Research Magnesium Taurate (Amazon affiliate link)
Also known as magnesium sprays or oils, this type of magnesium is placed topically onto the skin. The magnesium is then absorbed across the skin and into the circulation to help raise the serum level. A pilot study showed that spraying 56 mg/day onto the skin provided a clinically relevant rise in the serum level of magnesium in the body after 2 weeks ( 13).
This type of magnesium is particularly good for people who experience symptoms of leg cramp and muscle soreness. The exact dose will range from products but are set at 5-30 sprays/day or 2-4 tsp of magnesium cream.
Martina @ KetoDiet: Example product - Pure Zechstein Magnesium Oil Spray (Amazon affiliate link)
Like with transdermal magnesium, magnesium salts work by absorbing into the skin and entering the circulation. There are various types of salts, but the most common is that of Epsom salts, otherwise known as magnesium sulphate. As well as being good for sore or aching muscles, this type of magnesium can also be used as a relaxant. Low levels of magnesium have been linked to heightened stress ( 14).
It is recommended for this type of magnesium supplementation to fill a hot bath with 1-2 cups of Epsom salt and immerse the whole body for a minimum of 20 minutes to reap the benefits.
Martina @ KetoDiet: Example product - Epsoak Epsom Salt (Amazon affiliate link)
Poor Forms of Magnesium Supplements
The below options of magnesium supplements are less favourable forms of magnesium and where possible should be avoided.
Although this supplement is the most common form of magnesium, it has a very low bioavailability. This means that it is not well absorbed by the body. It also has an extreme laxative effect. Magnesium oxide is commonly used as a laxative in patients with constipation ( 15).
This is also known as magnesium l-aspartate. The jury is a little out on if this is a good or bad source of magnesium. This form of magnesium has increased bioavailability compared to others ( 16). Some people think that because it contains the name aspartate in it that this is the same as the artificial sweetener aspartame. However, aspartic acid is in fact an amino acid and a neurotransmitter in the body. This type of magnesium supplement is actually very difficult to find and purchase.
General Guidance on Magnesium Supplementing
As you can see there are a lot of different options when it comes to that of magnesium supplementation. If you are going to be taking oral magnesium, then try and stick to the good sources. If you find that you suffer a lot more from muscle soreness and cramps, then using a transdermal or magnesium salt option would be a lot better.
How and When to Take It
The normal dosing for oral magnesium is around 200-400 mg/day (17). This dosing would normally also be taken just once per day (i.e. not spaced throughout the day).
It is generally better to take magnesium along with food to mitigate any potential side effects.
If taking transdermal magnesium, then stick to the guidelines for the given source and do not go over the stated dose.
For Epsom salts, a 20-minute magnesium salt bath once per week has been shown to offer significant benefits.
Common Side Effects
Although there are some good and bad sources of magnesium, all the sources can cause some unwanted side effects if the stated dose is exceeded. The most common side effects are:
- Abdominal cramps
Although the gastrointestinal side effects listed above can be caused by all the forms of magnesium, generally magnesium oxide and chloride are the ones that have the biggest impact on the gut.
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