I reviewed my health diary notes to see what foods appeared to trigger excess mucus in me (as always, YMMV), and see what I had found re: orange juice, given that Ray Peat is such a proponent of it, which makes it somewhat relevant here.
Here are my notes from years ago, with a few minor updates. This was accumulated over quite some time, so there's probably more detail here than most would be interested in, but here it is, for any who are interested.
Foods and stimuli that cause (me) mucus, sinus congestion, runny nose and sinus drip and/or stomach upset
(BEFORE GLUTEN-FREE DIET YEARS AGO)
Strong reaction:
Orange juice (regular acid; low-acid OJ was much less of a problem)—throat mucus, acid stomach
Lemonade--throat mucus
Raw onions--acid stomach, heartburn
Fish oil tablets and gels—indigestion, gas (fish-flavored belches)
Cold weather—runny nose and sinus congestion, throat mucus, face mask helps
Beer, especially Sam Adams Boston Lager (high in acidic hops): acid stomach, reflux, heartburn, gas, flatulation, hangover headache from just a couple beers (whereas some other beers don't seem to have this effect with even more beers consumed)
0 – 3% fat milk (pasteurized cow's)--throat mucus
Ice cream--throat mucus, especially colder
Tomato sauce: acid stomach, stomach gas, reflux
Welshire Farms Hot & Spicy Tom-Toms Turkey Snack Stick (spices & lactic acid starter culture): burning stomach
Vegetarian "everything" pizza: stomach gas, belching, nausea, flatulation, and diarrhea
Red and green bell peppers (raw or lightly cooked)—stomach gas, especially green peppers
Cruciferous vegetables like cabbage and cauliflower—difficult to digest, stomach gas and belching
Caffeine—excess resulted in increased frequency of bloody noses and aggravation of stress, irritability, insomnia, anxiety and panic
Colas and root beer—throat mucus, anxiety
Milk-based yogurt (pasteurized cow's)--throat mucus
Cheese (pasteurized cow's)—throat mucus
Moderate reaction:
5% unsaturated fat soy milk--throat mucus
O.S. Cranberry juice from concentrate—throat mucus
Soy yogurt--throat mucus
3% "low fat" soy milk--throat mucus
0% "nonfat" soy milk--throat mucus
Mild reaction:
Cold beverages, including water--throat mucus (cold water causes throat mucus, hot water does not)
Pear juice--throat mucus
Grape juice--throat mucus
Cape Cod Cranberry juice (apple, grape, cranberry and lemon juice concentrates)--throat mucus
Recharge Tropical Thirst Quencher (concentrated white grape juice, hibiscus tea, orange extract, sea salt)—very mild throat mucus reaction
Cornmeal mush and fried cornmeal mush—runny nose
Power Bar: Banana (grape and pear juice concentrate, milk protein isolate)—throat mucus
Fruit sorbet—throat mucus (likely due to the coldness, maybe somewhat due to the fruit acid)
Foods that did NOT seem to cause throat mucus, sinus congestion, runny nose and sinus drip and/or stomach upset, or seemed beneficial
Apples—feel less malaise and nausea and more energy after eating; they seem to help bowels a bit
Low-acid fruits
Lean meats
Fish
Non-dense and low-acid vegetables
Soluble fiber
[and later on I found that raw meats, animal fats, and organs were very beneficial and raw fermented honey was quite beneficial in moderation, even though honey is generally highly acidic, though too much on an empty stomach does cause a burning sensation in my stomach]
It looks like acidity and coldness were two big factors for me in triggering mucus and other issues. Given that I'm handling lemon juice much better, I'm curious how well I'd handle OJ now and whether it would taste any better to me now, but I'm not sure I want to tempt myself, given the problems it caused me in the past.
I can drink ice cold water now without any throat or sinus mucus and cold weather triggers little or no mucus/congestion as long as I keep the raw animal fat intake high and the carb intake low (especially easily digestible carbs).
One of the interesting things about my health diary was that it pointed me away from modern foods and to Paleo foods other than acidic and sugary fruits/juices even before I learned the basic evolutionary nutrition hypothesis.
BTW, I should also note that all orange juice except fresh squeezed tended to give me a bad aftertaste that made it more and more unappealing to me, especially once I found much tastier foods that I also fared far better on. Fresh-squeezed OJ didn't have as bad an aftertaste.