From the Guidelines
Magnesium supplements, specifically magnesium oxide (MgO), can be an effective and attractive first-line option for individuals with chronic idiopathic constipation (CIC) at a dose of 500 mg/d to 1 g/d. When considering magnesium supplements, it's essential to note that MgO has been evaluated in randomized controlled trials (RCTs) and has shown to create an osmotic gradient in the GI tract, leading to net secretion of water and electrolytes, which can exert a beneficial effect on constipation-related symptoms 1. However, the bioavailability and clinical efficacy of other formulations of magnesium, such as citrate, glycinate, lactate, malate, and sulfate, are unknown for CIC.
Key points to consider when prescribing magnesium supplements include:
- Starting with a lower dose, such as 500 mg/d, and gradually increasing as needed and tolerated
- Avoiding magnesium supplements in individuals with significant renal impairment, specifically those with a creatinine clearance of <20 mg/dL, due to the risk of hypermagnesemia 1
- Being aware of potential interactions with other medications, such as antibiotics and blood pressure medications
- Combining supplementation with magnesium-rich foods like leafy greens, nuts, seeds, and whole grains for optimal results
It's also important to note that while magnesium citrate has been evaluated in other contexts, such as bowel cleansing for colonoscopy, its use in patients with chronic kidney disease should be avoided due to possible magnesium toxicity 1. Overall, magnesium supplements can be a valuable treatment option for individuals with CIC, but it's crucial to carefully consider the individual's renal function, medication interactions, and overall health status before initiating supplementation.
From the FDA Drug Label
Warnings Ask a doctor before use if you have kidney disease a magnesium-restricted diet stomach pain, nausea, or vomiting a sudden change in bowel habits that lasts over 14 days Ask a doctor or pharmacist before use If you aretaking a prescription drug. This product may interact with certain prescription drugs. Stop use and ask a doctor if you have rectal bleeding or no bowel movement after using this product. These could be signs of a serious condition. you need to use a laxative for more than 1 week If pregnant or breast-feeding,ask a health professional before use.
Magnesium supplements should be used with caution.
- Key warnings include kidney disease, magnesium-restricted diet, stomach pain, nausea, or vomiting, and sudden change in bowel habits.
- It is recommended to ask a doctor or pharmacist before use if taking a prescription drug, as interactions may occur 2.
- Stop use and ask a doctor if rectal bleeding or no bowel movement occurs after using the product.
- Pregnant or breast-feeding individuals should ask a health professional before use.
From the Research
Magnesium Supplements
- Magnesium supplements are available in various forms, including magnesium citrate, magnesium oxide, and magnesium sulfate 3, 4, 5.
- The effects of these supplements on arterial stiffness and blood pressure have been studied, with mixed results 3, 5.
- A randomized, double-blind, placebo-controlled trial found that magnesium citrate, magnesium oxide, and magnesium sulfate supplementation did not significantly change arterial stiffness or blood pressure in healthy overweight individuals 3.
- However, another study found that magnesium citrate and magnesium oxide supplements decreased 24-hour urine oxalate excretion and calcium oxalate supersaturation index in patients with idiopathic hyperoxaluria, with magnesium citrate having a greater effect 4.
Forms of Magnesium Supplements
- Magnesium citrate, magnesium oxide, and magnesium sulfate are commonly used forms of magnesium supplements 3, 4, 5.
- Magnesium citrate has been shown to increase plasma and urine magnesium levels compared to placebo 3.
- Magnesium oxide and magnesium sulfate have similar effects on plasma magnesium levels, but magnesium citrate leads to a more pronounced increase in 24-hour urinary magnesium excretion 3.
Clinical Applications
- Magnesium supplements may be used to reduce the risk of kidney stone formation in patients with idiopathic hyperoxaluria 4.
- Magnesium homeostasis is important in patients with chronic kidney disease, and certain drugs can affect magnesium levels 6.
- Regional citrate anticoagulation for continuous renal replacement therapy can lead to changes in total and ionized magnesium levels 7.