Acid-base disorders, when the usual homeostatic mechanisms are thrown off (either by disease or behavior such as bulemia) are serious cause for concern. Some review articles on acid-base disorders (acidosis and alkalosis):
Treatment of acidosis can involve IV injection of a base (bicarbonate), but note this is a controversial approach partly
because it messes with your blood pH (
Bicarbonate therapy in severe metabolic acidosis. - PubMed - NCBI).
It has become pretty common to use sodium bicarbonate, orally ingested, before exercise (the theory is to counter lactic acid), and it is known to cause an increase in blood pH. For one particularly well-designed study, see
The Reproducibility of Blood Acid Base Responses in Male Collegiate Athletes Following Individualised Doses of Sodium Bicarbonate.
Here is a plot from that study of blood pH (mean/sem) in controls (squares) versus treatments (circles and triangles) with sodium bicarbonate oral ingestion:
Clearly, orally ingesting a base can increase your blood pH significantly.Despite the fact that it has to go through your highly acidic stomach.
The question is, can the amounts we take in diet do the same, and does voluntary alkalosis actually influence performance in sports? It can be dangerous to mess with blood pH (hence the hesitancy to use bicarbonate IV even in cases of acidosis) so I would be *very* careful. In fact, I wouldn't mess with it.
Whether it actually improves sports performance, this is also controversial but studies suggest a modest effect (
Effects of sodium bicarbonate ingestion on anaerobic performance: a meta-analytic review. - PubMed - NCBI). This is why some sports agencies have considered banning it.
You can test for it by testing for... you guessed it, high pH of urine! This is discussed in this paper (
Changes in urinary pH following bicarbonate loading. - PubMed - NCBI) where the last line of the abstract reads, "These data indicate that urinary pH may be a suitable parameter for detection of bicarbonate doping." The problem is there are likely lots of false positives: you can generate alkaline urine via other means than taking sodium bicarbonate, so it likely would never fly as a test.
Upshot
I'm a skeptic in general. I like evidence-based medicine, and think homeopathy and chiropractic "medicine" are ******** (and I still do). I honestly went into Pubmed thinking I was going to debunk this stuff about pH, but came away realizing it is a lot more complicated than the people here crapping on the theories might lead you to believe. Note I'm not endorsing any weird diets or theories of blood pH being the cure for anything. I frankly wouldn't mess with that stuff. I'm just saying, after researching this for a little while this afternoon: it isn't all that simple. Ingesting things can significantly influence your blood pH, and this may have influence on athletic performance. Does this translate to eating high pH foods? I can't say, but I frankly would be surprised (because there's a world of difference between eating asparagus and taking a bunch of sodium bicarbonate) , but I have run out of energy to do more research. I'll wager this, though: eating healthy will make you healthier. So if those high alkaline foods are asparagus, broccoli, cabbage, etc, then go for it.
