Walk into your local supplement store, and you’re bound to find at least one shelf lined with a variety of magnesium supplements. Magnesium is popular for a reason: it’s one of the most important minerals in your body. But what does it do exactly? And why is it important for kidney health…….. And heart health….. and bone health…. and blood sugar regulation…… I could keep going here!
Firstly though- What is magnesium?
Magnesium is one of the key minerals that the body needs to stay healthy, in fact it is needed for more than 300 biochemical reactions in the body. Approximately 60% of the body’s magnesium is present in bone, 20% in muscle and another 20% in soft tissue and the liver. Less than 1% of total magnesium is in blood serum and our body works hard to try and keep these levels under tight control.
The majority of the population in Western countries consume less than the recommended amount of magnesium, in part due to the consumption of processed foods, demineralised water and agricultural practices using soil deficient in magnesium for growing food.
Role of magnesium in the body
Magnesium is required for so many processes in the body. Here are just some of them:
- Protein synthesis
- Muscle and nerve function
- Blood glucose control
- Blood pressure regulation
- Energy production
- Healthy brain function
- Immune function
- Formation of bone and teeth
- Important for the structure of many enzymes, mitochondria, DNA and RNA
Signs and symptoms of magnesium deficiency:
- Loss of appetite
- Nausea and vomiting
- Fatigue and weakness
- Numbness and tingling
- Muscle tightness, twitches and cramps
- Abnormal heart rhythm
- Personality changes
- Difficulty remembering things
- Low mood
- Hyperirritability and excitability
Health conditions associated with magnesium deficiency:
- Heart failure
- Ischaemic heart disease
- High blood pressure
- Cardiac arrhythmias
- Metabolic syndrome
- High cholesterol
Causes of magnesium deficiency
At least 50% of the population aren’t getting enough magnesium from their diet so this is obviously one possible cause of magnesium deficiency but there are also other factors that contribute to magnesium deficiency:
- Caffeine intake
- Alcohol use
- Soft drinks/soda that contain phosphoric acid
- Drugs such as diuretics (loop and thiazide), proton pump inhibitors (PPIs), tacrolimus, cyclosporine, digoxin, chemotherapeutic agents such as cisplatin, aminoglycoside antibiotics like gentamicin
- High stress levels
- Gastrointestinal diseases such as Crohn’s disease, Ulcerative colitis and Coeliac disease
- Insulin resistance and diabetes
- Older age
- Vitamin D deficiency
Being such an important mineral, the body works hard to keep magnesium levels within a specific range. Magnesium balance is largely maintained by the intestines, bone and kidneys. Intestinal absorption is dependent on magnesium status- the lower the magnesium level, the more is absorbed and vice versa.
Besides intestinal uptake, renal excretion is key in maintaining magnesium balance. The kidneys help to balance magnesium levels by increasing or decreasing the amount of magnesium excreted from the body.
In the later stages of CKD (typically stages 4 and 5), the kidneys can lose this ability to balance magnesium levels and have more trouble excreting magnesium in urine. This can result in elevated magnesium levels.
The role of Magnesium in Kidney Disease
Magnesium plays so many important roles within the body and not getting enough magnesium is linked to a variety of different symptoms and conditions. Having an adequate intake of magnesium is equally important for people with kidney disease. Studies show that magnesium deficiency in people with CKD is associated with a more rapid decline in eGFR.
Low magnesium is associated with a number of the known causes and potential consequences of kidney disease. So let’s have a look at some of these:
Diabetes is the number one cause of CKD worldwide. Magnesium is well known to play an essential role in the regulation of insulin actions and glucose levels within the body. Low magnesium levels have been associated with insulin resistance and type 2 diabetes and magnesium deficiency is more common in people with diabetes compared to the rest of the population.
Studies show that in people with diabetes, correcting low magnesium levels using magnesium supplementation improves insulin sensitivity and blood sugar control. This is key in preventing damage to organs like the kidneys.
Magnesium deficiency has been associated with a faster decline in kidney function in people with CKD and those with diabetes seem to be even more affected. Diabetics with low magnesium intake showed an even more rapid decline in eGFR and an increase in proteinuria (protein loss in urine), even if their blood sugar levels were well controlled.
High blood pressure
Low magnesium levels are also associated with high blood pressure, the second leading cause of CKD. High blood pressure doesn’t just contribute to kidney damage but also increases your risk of developing cardiovascular disease, heart failure and having a heart attack or stroke. Studies have shown that magnesium supplementation has been shown to lower blood pressure.
Inflammation and oxidative stress
Inflammation and oxidative stress have both been identified as being involved in both the development and progression of CKD (and most other chronic diseases). Low magnesium is associated with an increase in oxidative stress and increased production of inflammatory molecules.
Magnesium has been shown to fight inflammation, lowering inflammatory markers in the body. Magnesium is also a cofactor of several antioxidant enzymes in the body, for example, glutathione, one of the body’s primary antioxidants, needs magnesium for its production.
I also wanted to highlight the importance of magnesium when it comes to the development and progression of cardiovascular disease (CVD). The reason why this is important to mention is that people with CKD are at a higher risk of developing CVD (and vice versa) and inadequate magnesium has been associated with the development of CVD in people with kidney disease.
CVD is actually the leading cause of death in people with CKD so supporting cardiovascular health should be a key consideration for people with CKD.
Inadequate magnesium has been associated with the development of CVD and with an increased risk of non-fatal and fatal cardiovascular events. Low magnesium levels are frequently observed in people with high blood pressure, heart failure, cardiac arrhythmias, sudden cardiac death, coronary artery disease, high cholesterol and metabolic syndrome.
Other benefits of magnesium
- Lowers blood pressure
- Improves mood and lowers anxiety
- Improves sleep
- Reduces headaches and migraines
- Maintains normal heart rhythm
- Improves energy levels
- Lowers blood sugar
- Reduces inflammation and oxidative stress
- Reduces muscle tension and muscle cramps
- Improves bone density
- Support stress response
The next obvious question is- how do I know if I have low magnesium levels? That’s a great question which unfortunately doesn’t have an entirely clear answer!
The problem with diagnosing magnesium deficiency
Magnesium levels can be measured through urine but the most common and readily available tests are the serum magnesium and red blood cell (RBC) magnesium blood tests.
Serum magnesium is the most widely used test to measure magnesium levels. ‘Serum’ is the blood plasma- the clearish part of your blood. Unfortunately, serum magnesium tends to be the least accurate of the measurement methods and may not represent tissue levels or total body content of magnesium.
As I mentioned earlier, our body works really hard to keep blood magnesium levels within a normal range so it will pull magnesium out of bone and tissue if a drop in serum levels is detected. So, serum magnesium can test as ‘normal’ even when critical levels in the bone and tissue are decreasing and someone is actually deficient in magnesium.
Normal level: 1.6 – 2.6 mg/dL or 0.7 – 1.1 mmol/L (will differ slightly depending on lab)
Optimal level: >2.07 mg/dL or >0.85 mmol/L
RBC magnesium measures the magnesium concentration of your red blood cells, which is about 3 times higher than it is in your serum. RBC is seen as a more sensitive test in revealing magnesium deficiency because, as your body’s serum magnesium level decreases, the body reacts by leaching the mineral out of stores in your red blood cells, where it’s more abundant, in order to replenish serum levels. It’s like the old adage of ‘borrowing from Peter to pay Paul’- not a beneficial outcome.
Normal level: 4.2 – 6.8 mg/dL or 1.65 – 2.65 mmol/L (will differ slightly depending on lab)
Optimal level: >5.5 mg/dL or >2.26 mmol/L
Because testing magnesium levels isn’t completely accurate, it’s also important to assess for symptoms of magnesium deficiency and risk factors for developing magnesium deficiency.
Dietary Intake of Magnesium
Getting adequate amounts of magnesium from your diet is the best way to maintain magnesium levels.
Good dietary sources of magnesium include dark green leafy vegetables, nuts, seeds, legumes and wholegrains. Foods high in magnesium are often high in potassium as well so people following a low potassium diet are at increased risk of magnesium deficiency.
Unfortunately it’s not always possible to get enough magnesium from our diet, particularly if we are already magnesium deficient so in these cases magnesium supplementation may be required.
Because the kidneys are responsible for the excretion of magnesium, as kidney function declines this can mean that magnesium levels may become too high. This typically doesn’t become a problem until people are in stage 4 to 5 CKD. For this reason, those in the later stages of kidney disease shouldn’t take magnesium supplements unless they have their magnesium levels measured and discuss this with their healthcare provider.
There are many different types of magnesium supplements available, some being better absorbed and more bioavailable than others. Some of the best forms of magnesium include:
- Magnesium citrate- also has an alkalising effect on the body
- Magnesium glycinate- combined with glycine which has a calming effect on the body
- Magnesium malate- combined with malic acid which helps with energy production
- Magnesium orotate- particularly beneficial for cardiovascular disease
The usual therapeutic dose of magnesium is 300mg to 600mg a day.
In some people, magnesium supplementation can cause loose bowels. This is usually a dose dependent effect so I typically recommend starting at a lower dose of magnesium and building up over time to avoid this happening.
Before starting on any new supplement, make sure you discuss this with your doctor or naturopath to ensure that it is appropriate for your use and to determine the appropriate type and dose of magnesium. Magnesium does interact with some medications which is another reason to get professional advice before taking it.
Hopefully I’ve given you a better understanding of the importance of maintaining adequate magnesium levels, not only for your kidneys but also for your overall health and optimal functioning of your body. If you’ve found this article useful please let me know by clicking the ‘SHARE’ button below or leaving a comment on our Facebook page.