Sodium is a cationic metal that is essential to health. However, the Western diet is considered by many researchers to contain too much sodium chloride (table salt). The reason that the Western diet is high in sodium chloride is because it is used as a taste enhancer and as a preservative in processed foods. The body is able to excrete excess sodium, and so high intakes are not detrimental in the short term. However high intakes of sodium are often accompanied by low intakes of potassium, because the Western diet is also low in foods that contain potassium, including fruits and vegetables. This can cause an imbalance in the cationic minerals of the intra- and extracellular fluid of cells and cause changes to homeostatic regulation. In contrast, traditional diets tend to supply higher amounts of potassium than sodium, as such diets tend to be rich in unprocessed whole fruits and vegetables. Current recommendations are therefore to increase fruit and vegetable consumption and reduce intakes of processed salty foods.
However, while the sodium moiety of sodium chloride is often envisaged as the detrimental factor, the chloride ions may also have negative effects when in excess. For example, chloride ions in high amounts in the gut stimulate the release of bicarbonate, and this can deplete the bicarbonate stores of the body. In addition, high amounts of chloride in the nephrons of the kidney can inhibit the reabsorption of bicarbonate and increase bicarbonate excretion. In combination this can cause the bicarbonate concentration of the blood to fall, and this can modulate the acid-base balance towards that of acidity. As the pH of the blood falls, bone resorption increases, as the calcium in bone (another cationic mineral) can be used to buffer the excess hydrogen ion concentration in the blood. Excessive intakes of sodium chloride may therefore acidify the blood and lead to the excretion of calcium. This may have long term effects on the density of the skeleton, through chronic bone loss.
Because of the possible detrimental effects of diet containing too much sodium chloride, studies have investigated the effects of supplementing sodium chloride in the diet with other mineral salts. For example, in one study1, researchers investigated the effects of increased amounts of sodium chloride (225 mmol per day) on bone turnover in healthy women, and then examined the effects of supplementing the sodium chloride with potassium citrate (90 mmol per day). After consuming a low sodium chloride (87 mmol per day) diet for 3 weeks, the women were administered a diet containing either a high sodium chloride content or a high sodium chloride content supplemented with potassium citrate, for 4 weeks. On the high sodium chloride diet, the urinary calcium increased by 42 mg per day. However, the addition of potassium citrate lowered calcium excretion by 8 mg per day. In addition, markers of bone resorption also increased in the high sodium chloride diet, but not in the diet supplemented with potassium citrate.
Dr Robert Barrington’s Comments: These results suggest that foods containing potassium salts, such as fruits, may be beneficial at preventing detrimental changes to the acid-base balance of the blood. In particular, potassium salts may counteract the acidifying effects of excessive chloride intakes, as occurs in the Western diet. The long term implication of this are unknown, but by preventing the long term excretion of calcium caused by bone resorption, potassium salts may prevent bone diseases such as osteoporosis. Potassium salts also restore the correct sodium to potassium ratio, and this can have other beneficial health effects.
RdB
