There is a particular kind of exhaustion that arrives around the third week of a new city. Not jetlag — you adjust to that within days — but something slower, more systemic. A flatness behind the eyes. Muscles that feel slightly wrong. Sleep that doesn't quite restore. I noticed it first in Singapore, then again in Brussels, and I eventually stopped blaming the time zones.
A doctor in Geneva — the kind who asks what you've been eating before she asks what hurts — pointed at my diet log and said, quietly, "You're not getting enough magnesium." I had assumed supplements were for people who didn't know how to eat. I was wrong about that, and about several other things.
Here is what the science actually says, stripped of the wellness industry's enthusiasm: magnesium is essential. It is involved in over 300 enzymatic processes in the human body — muscle contraction, nerve signalling, blood pressure regulation, sleep architecture. A genuine deficiency is serious, and it is more common than you'd expect, particularly in populations eating heavily processed diets, people under chronic stress, and anyone whose body loses magnesium faster than usual (athletes, people who drink alcohol regularly, those on certain medications).
The complication is that "essential" and "you need to take a supplement" are not the same sentence. Research is consistent on this point: in people who are already getting adequate magnesium through food, supplementation adds very little. The body excretes what it doesn't need. You are, in that scenario, buying expensive urine.
Where supplements do earn their place is in genuine deficiency — and the gap between adequate and deficient is wider than most people realise, because magnesium is depleted by the very things modern life produces in abundance: cortisol, sugar, alcohol, poor sleep. The symptoms are diffuse enough to be mistaken for a dozen other things. Muscle cramps, poor sleep quality, low mood, fatigue, headaches. Nothing dramatic. Just a slow dimming.
The food case is straightforward and more interesting than capsules anyway. Dark leafy greens. Pumpkin seeds, which I keep in a jar in my kitchen in Valletta and eat the way other people eat crisps. Almonds. Dark chocolate above 70 percent cacao. Black beans. Whole grains. If your diet is genuinely varied, you are probably fine. If it is not — if you travel hard, eat on the run, rely on convenience — a supplement of 200 to 400mg of magnesium glycinate (better absorbed, gentler on digestion than the oxide form) is a reasonable bridge.
Tomorrow morning: add a small handful of pumpkin seeds to whatever you're having for breakfast. It takes five seconds and costs nothing worth counting.
Sophia Borg 
Dua Mifsud