Acid Or Alkali – What Does Food Choice Have To Do With It?
Whilst it is generally recognised and understood that diet is able to markedly affect acid-base status and that manipulating this may have a positive effect on conditions such as osteoporosis and kidney health, there is a great deal of misunderstanding as to how this may be best achieved.,
An established (and valid) method of estimating acid loads of foods or diets is by calculating the potential renal acid load (PRAL). PRAL provides an estimate of the production of endogenous acid that exceeds the level of alkali produced for given amounts of foods ingested daily.
The concept of PRAL calculation is physiologically based and takes into account different intestinal absorption rates of individual minerals and of sulphur-containing protein, as well as the amount of sulphate produced from metabolised proteins. This method of calculation was experimentally validated in healthy adults, and it showed that, under controlled conditions, acid loads and renal net acid excretion (NAE) can be reliably estimated from diet composition.
A common error by many people is to equate pH of drinks and foods with alkalising capabilities; this is a long way from chemical reality but remains a popular misconception – popular in that it is oft repeated with any qualification.
The pH of beverages and food has very little to to do with alkalizing the body. This may be a conflict with heart felt thoughts but it really is not an accurate chemical explanation.
The common misconception is that alkaline pH has the ability to neutralise metabolic acid and build alkaline reserves in vivo, therefore restoring balance to the pH of our body fluids and tissues. However, pH itself, no matter how alkaline, has little to do with the ability to neutralise acid.
What neutralizes acid is alkalinity (bicarbonate, carbonate, hydroxide), not pH! Alkalinity provides the buffering capacity that neutralises acid whether it is in a test tube or in the body. Alkalinity roughly refers to the amount of bases in a solution that can be converted to uncharged species by a strong acid and pH is just a measurement of the degree of the dissociation of H+ vs OH-. It takes alkalinisation and its various chemical transfers to neutralize acid.
Adding a few pH drops (usually of sodium and potassium hydroxide) to pure water makes its pH jump to 10, 11 or more. But drinking this will have no neutralising impact on acid state in the body. Because it lacks sufficient buffering capacity known as alkalinity, drops of this type might add about 20 mg of alkalinity – which is meaningless in supporting physiological pH balance.
It is possible to change acid status by using a simple alkalising agent such as baking soda that has a much lower pH of 8.4 in solution. Just 1/2 tsp of baking soda will deliver about 1500 mg of acid neutralising alkalinity.
An even better choice for alkalizing the body is achieved by drinking 1/2 litre of fresh green juice with spinach, kale, cucumber, celery, parsley, etc. This would deliver about 2000 mg of alkalinity in the form of a variety of alkalising mineral compounds. But here is the surprise…
The pH of ALL fresh green juices, which deliver the most beneficial alkalinity, is acid (e.g., pH 5.8 to 6.8).
The pH and the buffering alkalinity as you can see are disconnected parameters. In other words, an acid beverage with the right minerals can be very alkalising! Chemistry can be difficult to comprehend at times. Remember, lemons (acid pH) and apple cider vinegar (acid pH) and carbonated water, all acid, are great for alkalising the body, and whilst this is a very simplified version of the chemistry that takes place in vivo it covers the key points.
Key take away
Forget about the pH of anything you drink or eat. It is irrelevant to human physiology. It’s a misconstrued understanding based on a misconception.
To really determine if a food conveys an alkalising effect look for foods listed by their PRAL, the negative foods confer an alkalising effect and the positive ones an acidifying effect. A short but useful list cab be down loaded here: PRAL foods.
 Heil DP, Jacobson EA, Howe SM. Influence of an alkalizing supplement on markers of endurance performance using a double-blind placebo-controlled design. J Int Soc Sports Nutr. 2012 Mar 20;9:8 View Full Paper
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