Caroline, what you have written looks sensible to me. There is an account of the role of the parathyroid glands in regulating blood Ca2+ and phosphate levels here - Hyperparathyroidism. Symptoms; info on hyperthryroidism | Patient.

The RDA for phosphorus is 700 mg/day and the Tolerable Upper Intake Level is about 4 g/day. Serum phosphorus levels at the high end of the normal range (2.5-4.5 mg/dL) are risk factors for cardiovascular and kidney disease. Substitution of phosphate-containing soft drinks and snack foods for milk and other calcium-rich food may represent a serious risk to bone health. For more on this and references see Phosphorus | Linus Pauling Institute | Oregon State University. I am legally required to make this statement about this link "This link leads to a website provided by the Linus Pauling Institute at Oregon State University. I am not affiliated or endorsed by the Linus Pauling Institute or Oregon State University."

Part of my annual health check-up is measurements of my blood electrolytes (Ca2+, Na+, K+, phosphate, etc) - so far they have been comfortably within their normal ranges.

I agree with you about avoiding fizzy drinks and processed foods - they are likely to contain unhealthy amounts of phosphate and sugar (see above).

Sometimes, at social occasions, I will have a fizzy drink or some processed food, just to be polite - I figure that, as a "one-off", they will not harm me.