You'd never know it, from mainstream medical advice to limit salt. Health conscious people mostly add very little and can easily get low in hot weather. Lick yourself somewhere. Can you taste it?
Perspiration has lower content than blood, but exercise and hot days still mean salt loss. It's summery in my neck of the woods (Australia) and so quite relevant. A recent consultation with a young woman with migraine and nausea prompted me to write this page.
I was concerned to check for other causes for nausea. She had no abdominal pain nor tenderness to suggest gastritis. The optic disc of her retina was normal, with no papilloedema to suggest raised intracranial pressure. The examination for orthostatic hypotension however, was dramatically positive. Her blood pressure lying down was 124/77 but on standing up it dropped to 84/44 and she was unsteady.
Three twists of the salt grinder, water and a sleep and she was much better, but still with the migraine.
Mrs F was born in 1912. In 1999 she was no spring chicken and was giddy if she got straight out of bed in the morning. She had to sit on the edge for a while before standing up. Her blood pressure was 95/75 sitting. The old rule for acceptable systolic (top) reading was up to 100 plus one's age and hers was usually in the range 110 to 140. Extra salt was advised and three months later I wrote "less giddy, balance better."
We talk about atomic and molecular weights of substances to measure how heavy each is. Sodium is 22.99, chloride is 35.45, so salt (sodium chloride) is 58.35.
You may read an amount of sodium as say 150 mmol (0.150 mole.) There are 22.99 grams of sodium in one mole, so 150 mmol equals 3.45 gram of sodium (22.99 multiplied by 0.150.)
That is just the sodium, contained in 8.75 grams of sodium chloride (58.35 X 0.150.) Despite the confusion on the net, sodium does not equal salt.
A teaspoon of salt weighs 5 gm or 5000 mg.
"CONCLUSIONS In patients with type 2 diabetes, lower 24-h urinary sodium excretion was paradoxically associated with increased all-cause and cardiovascular mortality. Interventional studies are necessary to determine if dietary salt has a causative role in determining adverse outcomes in patients with type 2 diabetes and the appropriateness of guidelines advocating salt restriction in this setting."4. Page on surrogate markers.
"Conclusions In this population-based cohort, systolic blood pressure, but not diastolic pressure, changes over time aligned with change in sodium excretion, but this association did not translate into a higher risk of hypertension or CVD complications. Lower sodium excretion was associated with higher CVD mortality."