I heard often that coffee deplete magnesium in your body, both in ads for magnesium supplements, on so called "wellness" websites but also on some scientific papers.
Some sources claim that it's because coffee decrease absorption of magnesium and other that also coffee is a diuretic, so you lose magnesium while urinating.
Here are examples:
When you drink coffee, your intestinal absorption of magnesium decreases. Although coffee does not directly deplete magnesium from your body, the decreased absorption of magnesium can cause your body to gradually lose magnesium, potentially resulting in a magnesium deficiency. The more coffee you drink, the less magnesium your intestines can absorb. This becomes more important as you get older, as magnesium absorption typically decreases with age.
The multifaceted and widespread pathology of magnesium deficiency in Med. Hypothesis.
Mg levels are decreased by excess ethanol, salt, phosphoric acid (sodas) and coffee intake, by profuse sweating [...]
But I stumbled upon other claims, that coffee might provide you with more magnesium than you will lose after drinking it, so you might even end up with a little more magnesium. Mostly I heard it from Polish Youtube Channel, Pod Mikroskopem. The presenter, Patryk, has an education in some medical sciences.
He provides his sources to this video:
- R. Preedy Victor: Caffeine: Chemistry, Analysis, Function and Effects. Food and Nutritional Components, 2012.
- Orey C. Kensington Books, 2012.
- Zand J.: Smart Medicine for Healthier Living. Avery Publishing Group, 1999.
- Świątkowska K.: Kawa kontra magnez (...) (dostęp 21.09.2018)
- Sarobo C.: Int J Exp Pathol. 2012, 93(6):429-37.
- Ming Z.: Can J Physiol Pharmacol. 2010, 88(11):1115-21.
- Robert A.F.: Am J Physiol Renal Physiol. 2015, 15; 308(12): 1409–1420.
I can not find any strong statement that coffee cause magnesium depletion, like research focused on relation between coffee and magnesium level while stumbling upon claims that it might even increase magnesium level. Also some studies mentions that:
Instant coffees and coffee substitutes are rich in K, Mg and P (>100 mg/100 g dw) https://www.sciencedirect.com/science/article/pii/S0308814611010880
Coffee is a better source of potassium than tea, has appreciable amounts of magnesium, and may contribute significantly to manganese intakes in some instances https://www.ncbi.nlm.nih.gov/pubmed/6650450