Several statements posted in this thread are not precise enough:
The 'doctor' who wrote the article is completely mistaken. The entire medical community knows that the condition called 'gout' is caused by excess uric acid in the blood stream, caused primarily by eating too much protein, especially shellfish.
The excess of uric acid does not mean that the blood is excessively acidic, uric acid is in the equilibrium with its' salt at the normal pH 7.4. The excess of uric acid precipitates in the organism with unfortunate consequences, but it does not lower the pH of the blood.
Citric acid is acidic, but makes your body more alkaline. This is true of almost every fruit you can eat. Your stomach neutralizes the citric acid and it becomes citrate. Citrate is a precursor to bicarbonate. Similarly, instead of eating lemons or citric acid, you can take sodium citrate or potassium citrate, which I have also tried. It has the same effect except is more gentle on your teeth.
In terms of pH, citric acid and citrates are two completely different entities: while citric acid is an organic acid, which lowers pH, citrates are its' salts which indeed can increase pH (triple natrium salt of citric acid is basic). However, the organism must invest an effort (in terms of buffering) in order to neutralize citric acid (i. e. to transform it to the sodium salt). This can not be done in the stomach, because it is strongly acidic (contains even free hydrochloric acid, which would immediately convert any organic salts into free acids). It is only after, in the intestines, where pH increases.
The most important buffers in the blood are bicarbonate anion and hemoglobin (some plasma proteins also play a role). Any acid in the blood stream is neutralized by bicarbonate anion, which is thus transformed into carbonic acid. Hemoglobin binds carbonic acid, takes it to the lungs, where it is eliminated as CO2. Thus, from the chemical point of view, taking acids (like citric acid) before a dive does not make sense. However, the human physiology might be more complicated (with respect to simple chemical logic), and it may be that the intake of acids activates some defense mechanisms, which increase buffering capacity.
As of taking sodium-bicarbonate in order to increase pH - it is immediately neutralized in the stomach with the production of large amount of gaseous CO2, which induces bad feeling and problems with digestion. It might have some effect with respect to increasing the pH in the blood, but this is an agressive and unhealthy way to do that, and it should be avoided.
Radomir