Here is some evidence to back up the above claims. There is plenty of it.
1. Hypokalemia (potassium deficiency).
https://www.thailandmedical.news/ne...lemia-present-in-almost-all-covid-19-patients
Clearly, having naturally high levels of Potassium can only help.
WARNINGS:
- DO NOT INCREASE THE LEVEL OF POTASSiUM IN YOUR BODY UNNATURALLY! IT CAN BE FATAL
- Some people with Kidney disease need to have a low potassium diet.
- Some asthma medication lowers potassium levels but the medicine literature will tell you to have a high potassium diet to counter this.
https://www.msdmanuals.com/en-gb/ho...pokalemia-low-level-of-potassium-in-the-blood
If in doubt talk to a doctor.
2. Vitamin D.
WHO:
https://www.who.int/elena/titles/commentary/vitamind_pneumonia_children/en/
Vitamin D and Coronavirus (take some of this evidence with a pinch of salt but the volume of evidence is overwhelming):
https://vitamindwiki.com/COVID-19+Coronavirus+can+most+likely+be+fought+by+Vitamin+D
Taking too much Vitamin D can be bad for you, but with the UK climate, and it's lack of sunlight, most people are naturally slightly deficient.
3. Boosting the immune system
3.1.1 Vitamin C:
Is isn't a wonder drug or silver bullet, but it does help.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2099400/
Having a balanced diet is key to fighting any infection and taking a multivitamin is sufficient to boost your system, but when you get ill, every little boost helps.
3.1.2 Zinc:
Zinc is a well known aid to help against cold and flu. The reason is it interferes with RNA virus replication.
Is isn't a wonder drug or a silver bullet, but it does help when you get ill.
https://www.researchgate.net/public..._Replication_of_These_Viruses_in_Cell_Culture
3.2 Echinacea:
There is plenty of evidence out there that indicates that this extract is a natural anti-viral medicine.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4058675/
4. Gargling with very warm salt water
Plenty of rebuttal evidence out there for this. Especially if you have high blood pressue (so don't if you have)
https://www.snopes.com/fact-check/gargling-eliminate-coronavirus/
But... Gargling with salt water does ease a sore throat. Warm water is better still. You only need a little salt though 1/3 of a teaspoon for a small beaker. Also any delay in virus build up gives your body more time to fight it. So it ain't a cure but unless you've got high blood pressure it's worthwhile.
I should also have mentioned that if you have Asthma you need to make sure you are managing your illness to the best if your ability. The higher your peak flow level if you get it, the more likely you are to not need medical intervention.