Hi,
I have no idea if we've just been lucky or the combination of things we do have kept him healthy, but our son is 15 months and only got his first cold at 14 months for only 3 days. So I'll just share what we do.
We only eat local organic meat/produce/dairy and no processed foods. We drink raw milk. My son has never eaten anything processed or synthetic and I cook from scratch.
We breastfeed and plan to continue to 2-3 years or until I'm pregnant again.
He gets a tablespoon of raw organic coconut oil daily. (HUGE immune booster and great for teeth and bowels and everything else)
We go outside for at least 3 hours a day rain or shine or snow or heat.
He has plain yogurt daily for probiotics.
We don't vaccinate or give him any kinds of Rx or OTC drugs. We use homeopathic remedies.
That's us, but I'm not suggesting you need to mimic everything. I will stress the coconut oil. I think it does wonders. I take 3 tsp 3 times a day and cook with it. Just something to try.