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300 mg Magnesium Oxide Supplement

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Magnesium Oxide to support heart, bone, energy, bowel regularity and acid indigestion.† Contains 300 mg elemental magnesium in a vegetarian capsule.

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Magnesium Oxide
Supplement Facts

Serving Size: 1 capsule
Servings Per Container: 100
Ingredients Daily
% Daily
Magnesium (from 500 mg Magnesium Oxide) 300 mg 71%

Other ingredients: Hydroxypropyl methylcellulose (capsule), microcrystalline cellulose, carnauba wax, ascorbyl palmitate, hydroxypropyl cellulose and silica.

Cooper Complete Gluten Free iconCooper Complete Non GMO Icon

This product is gluten-free, non-GMO.

WARNING: If you are pregnant or nursing, or if you are taking prescription medications, consult your health care professional before using this supplement.

While we strive to ensure the label information on this site represents the label on the product available for purchase, products are updated from time to time. Please consult the label on the product you purchase for the most accurate ingredient and allergen information.

Item Number: 166
SKU: 816899000614
Formula: 202434-100-PL-84121312-V0520

What It Is

Magnesium Oxide from Cooper Complete helps support:

  • Bone health
  • Energy production
  • Heart health
  • Bowel regularity

How to Use:

As a dietary supplement, take one (1) magnesium oxide supplement capsule daily or as directed by your health care professional. Each bottle contains 100 servings.

How It Helps

Magnesium Oxide Supplement provides 300 mg elemental magnesium from 500 mg magnesium oxide. Magnesium is involved in more than 600 biochemical reactions in the human body. Every cell in your body contains it and needs it to function.

Bone Health:

  • Calcium levels in the bones are regulated by magnesium

Energy Production:

  • Magnesium Oxide helps convert food, especially carbs, into energy for the body

Heart Health:

  • Magnesium Oxide helps protect blood vessels by helping them relax and pump at a lower pressure

Bowel Regularity

  • Healthy magnesium levels help stimulate bowel regularity

Cooper Complete products are verified and lot tested. If you would like a copy of a Certificate of Authenticity for a specific product or would like to learn more about our testing process and results, please contact us at customerservice@coopercomplete.com or call our team directly at 888.393.2221 9 a.m. until 5 p.m. Monday-Friday central time (CST).

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What Our Customers are Saying

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Reviews of 300 mg Magnesium Oxide Supplement

  1. I love the Cooper Complete Magnesium Oxide. I am sleeping much better!

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Customer Q&As

If you have questions, we have answers. See what real people are asking about Cooper Complete products.

10 Questions
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Has magnesium oxide been widely studied?


Yes. PubMed Central (PMC) has thousands of research articles on magnesium oxide.


Should I take calcium with magnesium?


Calcium and magnesium have a complicated relationship. Magnesium is essential for the absorption and metabolism of calcium inside the body. It’s important to keep these two minerals in balance. Too much calcium and/or too little magnesium can have negative health effects. It is important to speak with your physician before taking supplements to understand your specific needs.


What are magnesium deficiency risk factors?


Older adults, people with diseases of malabsorption such as Crohn’s disease and celiac disease, type 2 diabetics, and alcoholics are all at risk of magnesium deficiency. Long time use of prescription diuretics can increase magnesium loss in urine and deplete magnesium levels.


What are signs of magnesium deficiency?


Magnesium deficiency can contribute to muscle spasms, osteoporosis, fibromyalgia, arrhythmia (AFIB) and migraines.


When should I take Magnesium Oxide?


We suggest magnesium oxide supplements be taken with your morning meal. Consult with your physician whether Magnesium supplements should be taken with osteoporosis medication or antibiotics.


How much elemental magnesium is in each capsule?


Each Cooper Complete Magnesium Oxide Supplement provides 300 mg elemental magnesium in each serving of one capsule.


How much magnesium should I take per day?


The Recommended Dietary Allowance (RDA) for magnesium varies by age and gender. Adult women need 310-360 mg per day while adult men need 400-420 mg. Since health conditions and illnesses can impact the amount of magnesium needed, it’s important to speak with your physician to understand your specific needs.


What foods contain magnesium?


Good food sources of magnesium include leafy vegetables, whole grains, bananas, nuts, seeds and legumes. Water can also contain magnesium but the amount of magnesium can vary widely. Food processing erodes magnesium in foods. Despite the prevalence of magnesium in food, US dietary surveys typically find magnesium intake less than recommended.


Does Magnesium Oxide have a laxative effect?


A common complaint about magnesium oxide is the laxative qualities of magnesium so we suggest that you start with one pill, and increase as needed from there. Taking magnesium with food can reduce the occurrence of diarrhea. Magnesium Glycinate should be considered if diarrhea or other gastrointestinal distress occurs.


What is Magnesium Oxide?


Magnesium oxide (MgO) is an inorganic compound that occurs in nature as the mineral periclase. It is the oxide salt of magnesium. In addition to its benefits for bone health, energy production and heart health, it is also often used as an antacid and mild laxative and has many nonmedicinal uses.