My friend says if he eats a salty meal, like sushi with soy sauce, or proscuitto or sausage, his hands feel different - not sore, but like it's harder to grip his water glass. I've never heard of this before. What's the science behind it?
Those items have much worse offending factors than the salt. Soy sauce can especially has all kinds of nasty stuff. Between that and the sausage he could be dosing with soy, weat, MSG, and sugar along with the salt.
I agree with Loon--when I had those symptoms I thought it might be salt but they went away when I stopped eating wheat; my salt intake was also lower, so I can't be 100% sure but ancestral eating is definitely a cure for me.
When I first saw this question I assumed your friend must be eating the SAD, because ancestral eating is a very low sodium regime in comparison.
Since we're eating whole meats, fruits and vegetables the salt we take is in limited to whatever we add. I know uncured bacon is salty so when I have it I don't salt the meal and 2 slices of it is still a reasonable sodium intake. I rarely eat other processed meats.
Could it be he's retaining enough fluid to feel it in his hands? That would make bending your fingers take a little more effort. My elderly dad-in-law is forbidden to eat salt due to how severe his water retention is from it.
I used to think this was due to salt since I used to get it after eating pizza. But then I realized that it was just due to wheat. I can eat a ton of salty green olives with no problem as long as I drink enough water.
Could it be water retention due to excess salt? I know when I'm imbalanced with my hydration (due to too salty meals, not drinking enough water, hot weather) my hands get somewhat swollen and feel a little tight.
High salt causes adrenaline surges, your friend could be experiencing stiffness due to the adrenaline http://www.scientificamerican.com/podcast/episode.cfm?id=salt-boosts-bp-but-via-adrenalin-12-01-11 adrenaline causes muscles to weaken for fight or flight.
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