How do you get people to consume spirulina? Preference and taste get involved. Everyone eats salt. Salt was used to preserve things. Salt is used as a flavor enhancer. Salt is consumed far more ubiquitously than anything else. And, it doesn’t spoil if you dont consume it all in a couple weeks.
"How do you get people to ____" is a fundamental question in life with many approaches to answering it, ie marketing, public relations, missionary studies, theater, etc.
Are you being intentionally obtuse? You asked why salt, he answered with literally the most important reason in public health: people actually use it. It is a known delivery vector that works, period.
And, yes, no shit. How to get other people to do something is a fundamental question in life and it just so happens that in life, public health is about getting people to do stuff that's good for their and society's health.
Yes. How can we help improve nutrient availability, generally?
From what I pointed out below, this salt processing seems to have underappreciated trade offs. But most importantly, the overarching picture of nutrient availability, not just for iodine, seems to have a bigger challenge at hand worth solving than simply using salt as a vehicle for one - which spirulina would help with in terms of protein and mercury / biotoxin removal, for example.
Spirulina is not a good source of iodine anyway. Unlike kelp, which grows in iodine-rich ocean waters (and which is a decent source of iodine), spirulina is generally grown in alkaline inland lakes (read: iodine-depleted).
And it this case it appears that spending a buck to iodize a few tons of salt is probably easier or at least easy enough that it doesn't make sense to go through the effort to switch to something else.
Yeah, but salt, unlike many other alternatives, was almost universally used—no challenges getting people to use it—and is ideal as a vehicle. So salt it was.
And, sure, there may have been some other equally good alternatives, but analysis paralysis helps no one. So, salt.
I don't know what idealistic/philosophical point you are trying to make, but we also do things like water fluoridation. Salt happens to be a very convenient medium for iodine.
Well, this assumes that the local populace will reliably eat the spirulina. The nice thing about salt, is that you only have to solve the problem of getting people to eat the salt that you've iodized. You don't have to solve the additional problem of getting them to eat salt in the first place.
If you're running some sort of anti-malnutrition campaign that involves local cultivation of spiritual then sure, why not add iodine to it? (Assuming that this is technically feasible. Don't know whether it is or not.) But if you are trying to solve the specific problem of iodine deficiency, then I'm not sure why you would start with "first, grow a bunch of spirulina..."
Plants do not produce iodine (it's an element), and they can only accumulate it from the environment. People living in environments rich in iodine, likely, do not need iodine supplementation.
Adding a small bag of sodium iodate to a big bag of sodium chloride and mixing requires no skill or special equipment and any idiot, or shall I say cretin, can do it. Whereas running a bioreactor and somehow convince people of eating the gunk that comes out of it is far more complicated and expensive.
Edit: and you'd still have to add iodine to said bioreactor, you might as well add it directly to the salt.