There are many, many books written on the benefits of an alkaline diet. What I was interested in was some solid scientific evidence about whether an alkaline diet was something worth pursuing. And I think I found it. The take home message is that you probably need to watch your sodium intake and boost your potassium, and your magnesium while you’re at it – but not much more than that. Read on for more details.
The logic around the proponents of such a diet goes something like this. As a species, our behaviour has changed as we moved from hunger-gather societies, through the agricultural revolution, and then even more rapid change through industrialisation. Alongside this, our diet has decreased in potassium compared with sodium. Where the potassium / sodium ratio was once 10:1, this is now 1:3. It’s also widely accepted that humans who have an agricultural based diet tend to take in a combinations of foods that are poor in magnesium, potassium and fibre, as well as increasing levels of saturated fats, simple sugars, sodium, and chloride compared with pre-agricultural times.The argument is that this results in a diet which may trigger metabolic acidosis – which doesn’t fit well with our genetically programmed nutritional requirements. Add to this the impact of aging. As we grow older, there is a gradual decrease in the ability to regulate certain processes involving the kidney which means that diet-induced metabolic acidosis becomes even more likely on a modern diet.
pH – which is a measure of acidity / alkalinity – varies throughout the body. An acid pH of 1.5-3.5 in the stomach helps with digestion and helps to nuke any nasty bugs that might try to invade us an infect us through our alimentary canals. The skin is also quite acidic to provide a protective barrier against microbial overgrowth. So acidity can be useful. But a high acid load in the body such as that produced by a typical modern diet can cause the leaching of calcium salts into our urine to try to counteract this acidity. Some say that this may have an impact upon bone health and increases risk for osteoporosis, but the evidence looks more complicated that, with a recent systematic review finding no causal link between dietary acid load and bone disease.
Another major concerns is loss of muscle mass as we age. A 3-year study into a diet rich in potassium seemed to suggest a reduced acid load alongside preservation of muscle mass for older men and women, and there is further evidence that correction of acid-producing diets may preserve muscle mass in conditions which would otherwise lead to muscle wastage, such as COPD or renal failure.
For athletes, an interesting study found that supplementation of diet with sodium bicarbonate prior to exhaustive exercise resulted in significantly less acidosis in the blood than those who didn’t get the sodium bicarbonate supplementation (by the way, please don’t just dump sodium bicarbonate in your water now – that is very risky, and you need to be careful about it – check the original paper to see what they did, or take other advice). Unfortunately, another study indicates that although blood pH may be changed by taking such buffering solutions, it didn’t necessarily change running performance.
In sum, the body seems to show a remarkable capacity to maintain a steady pH in the blood, and the compensatory mechanisms to deal with any fluctuations seems to work pretty well. However, there is some evidence that the potassium / sodium ratio does matter, and that the significant level of salt in our diets doesn’t help. Muscle wasting appears to be reduced with alkaline-promoting diets, and back pain might benefit from this too.
To help yourself, increase the amount of fruit and veggies in your diet – some are better than others. There doesn’t seem to be any definitive acid / alkaline taxonomy that I could find, but look out for foods that boost your potassium level while trying to cut out sodium. Magnesium is good too – and although most people should get this in their diets, if you’re existing on a lot of processed food, you may be missing out. In New Zealand, the soil is missing a lot of key minerals, and that should also be a consideration when you’re thinking about the mineral content and balance in your diet.