Here’s a detailed explanation.
What is Magnesium Glycinate?
Magnesium glycinate is a dietary supplement made by combining:
- Magnesium, an essential mineral needed for over 300 biochemical reactions.
- Glycine, an amino acid that may have calming effects.
It is commonly used to:
- Improve sleep
- Reduce muscle cramps
- Support nerve and muscle function
- Help with migraines
- Reduce anxiety in some people
- Correct magnesium deficiency
Compared with other forms (like magnesium oxide), glycinate is well absorbed and less likely to cause diarrhoea.
The “One Habit” That Can Make It Dangerous
The biggest risk is:
Taking magnesium supplements despite having reduced kidney function
This is particularly important for older adults.
Healthy kidneys remove excess magnesium from the body.
If the kidneys don’t work properly, magnesium can build up in the bloodstream, leading to hypermagnesemia (high magnesium levels).
Older adults are at higher risk because kidney function often declines with age, even without obvious symptoms.
Why This Can Become Toxic
Normally:
- Magnesium absorbed from food or supplements
- Excess is filtered by the kidneys
- Extra magnesium leaves the body in urine
But when kidney function declines:
- Magnesium accumulates
- Blood magnesium rises
- Nerves and muscles stop functioning normally
- The heart can be affected
Severe cases can become life-threatening.
Symptoms of Magnesium Toxicity
Early symptoms
- Nausea
- Vomiting
- Facial flushing
- Feeling unusually sleepy
- Weakness
- Dizziness
Moderate symptoms
- Low blood pressure
- Muscle weakness
- Difficulty walking
- Slowed reflexes
- Blurred vision
Severe symptoms
- Trouble breathing
- Very slow heartbeat
- Heart rhythm abnormalities
- Confusion
- Paralysis
- Cardiac arrest
- Coma
These severe outcomes are uncommon and usually occur in people with significant kidney impairment or very high magnesium intake.
Other Habits That Increase the Risk
1. Taking more than recommended
Some people assume that if one capsule is good, several must be better.
Large doses over time increase the risk of side effects and toxicity.
2. Combining multiple magnesium products
For example:
- Magnesium glycinate
- Magnesium citrate
- Electrolyte powders
- Multivitamins
- Antacids containing magnesium
- Laxatives containing magnesium
The total magnesium intake can become much higher than intended.
3. Using magnesium-containing laxatives regularly
Examples include:
- Milk of Magnesia
- Some bowel-preparation products
These products contain much larger amounts of magnesium than typical supplements.
4. Ignoring kidney disease
People with:
- Chronic kidney disease
- Kidney failure
- Dialysis
- Reduced kidney function
should only use magnesium supplements under medical supervision.
5. Taking magnesium with certain medications
Magnesium can interact with:
Antibiotics
It reduces absorption of:
- Tetracyclines
- Fluoroquinolones
These medicines should generally be taken several hours apart from magnesium.
Thyroid medication
Magnesium can reduce the absorption of levothyroxine. It is usually recommended to separate doses by several hours.
Osteoporosis medicines
Bisphosphonates can also be affected by magnesium if taken too close together.
Who Is Most at Risk?
Higher-risk groups include:
- Adults over 65
- People with kidney disease
- Those taking large doses of magnesium
- People using magnesium laxatives frequently
- Individuals taking multiple magnesium-containing products
- People with dehydration or severe illness
How Much Magnesium Is Safe?
The recommended daily intake from all sources varies by age and sex.
For adults:
- Men: about 400–420 mg/day
- Women: about 310–320 mg/day
The tolerable upper intake level for magnesium from supplements and medications (not food) is 350 mg/day of elemental magnesium for most adults, unless a healthcare professional recommends otherwise.
Many magnesium glycinate products provide 100–200 mg of elemental magnesium per serving, but the amount varies by brand, so it’s important to check the label.
Can You Get Too Much from Food?
It is very unlikely.
The kidneys usually eliminate excess magnesium from foods such as:
- Spinach
- Pumpkin seeds
- Almonds
- Cashews
- Black beans
- Whole grains
Toxicity from dietary magnesium alone is rare in people with normal kidney function.
Signs You Should Stop the Supplement and Seek Medical Advice
Contact a healthcare professional promptly if you develop:
- Persistent nausea or vomiting
- Severe weakness
- Marked drowsiness
- Slow or irregular heartbeat
- Difficulty breathing
- Confusion or fainting
These symptoms warrant prompt evaluation, especially if you have kidney disease or have taken large amounts of magnesium.
Tips for Safe Use
- Follow the dosage on the product label or your healthcare professional’s advice.
- Avoid taking multiple magnesium-containing products unless advised to do so.
- Tell your doctor or pharmacist about all supplements you take.
- If you have kidney disease or reduced kidney function, consult your healthcare professional before using magnesium supplements.
- Separate magnesium from certain medications (such as some antibiotics, levothyroxine, and bisphosphonates) according to your healthcare professional’s instructions.
Bottom line
For most healthy adults, magnesium glycinate is safe and well tolerated when taken at recommended doses. The greatest concern for toxicity is using magnesium supplements despite impaired kidney function, because the body may be unable to remove excess magnesium effectively. Toxicity from standard doses in people with normal kidney function is uncommon.