Here is a casual recording I did:
When singing through a song with only one try, diet can really start to make a difference. If their is a thicker film on your vocals, you don't always have time to clear it (which can start to cause its own irritation). For higher female voices this is even more important. Soprano singers have thinner vocal chords and hence, can't take the damaging effects of growling, screaming, or rough singing styles as well as alto or male vocalists.
With poor diet, not only will there be more rough texture in my voice but also a decrease in range from less vocal flexibility and a breathier tone. It really sounds ridiculous, but after years of trial and error this genuinely seems to be the case.
So then what is one to do?
If you are experiencing similar vocal issues, give exercise and an elimination diet a try. Eat essentially fruits, vegetables, meat/seafood, legumes, and nuts if you aren't allergic. For noodles try bean noodles or Korean sweet potato noodles and have 10% or less of your diet consisting of grains of your choice. I usually stick to rice. Pair this with regular exercise, regular hydration, and only gentle vocalization. When I have faithfully followed this, there is a definite pay off. Unfortunately, in the past I tend to fall into my bad habits again of eating too much sugar, dairy, or a high carb diet. These seem to dry out the throat and cause increased mucous.
When you have already tried the more straight forward methods like not over training your voice, straining, smoking etc, definitely give this a try for two weeks and see what it does for you. After the holiday chocolates and hearing the effects, I'm on my fifth day of this diet and looking forward to it clearing up ♪ヽ(´▽｀)ノ
But for now, I believe it is time for me to start going on short hikes in the woods again. After the passing of my dog and companion in the woods I'll admit I have been avoiding it for that reason. But as somebody who grew up spending part of nearly every day walking out in the woods or on the coast, it is starting to feel quite awkward to leave that behind. It is bittersweet.