For starters I think most people agree there is no need to replace electrolytes during endurance activities that do not exceed 1 hour, oddly the length of time in this study. I’m not sure anyone claims coconut water hydrates better than water, but certainly it’s going to be more beneficial for replacing lost electrolytes. Personally, I’d like to see a study regarding coconut milk vs water and the hydration effects on the intestines themselves, my hypothesis would be intestines hydrated with coconut milk more readily absorb vitamins and nutrients from other foods than intestines hydrated with just water, either way it would be an interesting experiment.
As to chia seeds being compared to salmon, that alone should probably confirm their status as a food rich in omega 3 fatty acids, as salmon is one of the best sources of omega 3 fatty acids. But what’s the use case? As a runner I am more inclined to drink water or coconut milk with a teaspoon of soaked chia seeds rather than run with a belly full of salmon, but for dinner I’d rather have a plate of salmon than a teaspoon of chia seed. And omega 3s are not the sole benefit of chia seeds, As natures form of time release capsules they will provide some degree of continued hydration during long runs from the liquid they were soaked in that salmon will not. It seems they could have measured the hydrating effects of the chia seed vs the salmon, but instead they only seem to focus on the percent of omega 3 obsorption of chia vs salmon, but as I said these were oddly isolated measurements.