Phosphorus is an important macromineral required for cell function. Phosphorus forms part of the phosphate molecule, and in this regard is required for the utilisation of energy by ATP and the synthesis of glycogen from glucose in skeletal muscle and liver. Phosphate molecules also form the backbone of the DNA molecule and so are integral in the storage of genetic information. The correct formation of phospholipids also required dietary phosphorus such as lecithin, which are required for fatty acid transport and metabolism. Correct phosphorus to calcium balance is required for health and this ratio is estimated to be around 1 part phosphorus to 2.5 parts calcium. Deviations from this ratio in the dietary intake of calcium and phosphorus may lead to incorrect bone mineralisation. Most Western populations obtain adequate phosphorus from their diets. In fact the phosphorus intake of most is considered too high, which disrupts the correct calcium to phosphorus ratio, and this may be a cause of ill health.
The role of phosphorus in human health has been neglected to some degree, with far more research concentrating on the effects of calcium. However, the fact that minerals are required in balanced ratios has only recently been accepted as important and worthy of research in academic circles. Research into phosphorus intakes shows that not only are they too high in Western nations, but also that this high intake of phosphorus is associated with mortality. For example, in one study, the phosphorus intakes of healthy United States living adults between the ages of 20 and 80 were assessed using 24 hour dietary recall questionnaires, and subsequent all cause and cardiovascular mortality was assessed through medical records1. The phosphorus intake of the subjects was 1166 mg per day, which is above the recommended intake (700 mg per day). Intakes above 1400 mg per day phosphorus were associated with higher all cause mortality in the subjects, but there was no such association with intakes below 1400 mg per day.
When the phosphorus density of the diets of the subjects were considered by the researchers, similar associations with mortality were found. In particular, densities over 0.35 mg per kcal of energy were associated with an increased risk of total mortality. However, phosphorus densities above 0.35 grams per kcal of energy were associated with increased cardiovascular mortality risk. Therefore in the population studied, there appears to be a threshold for total phosphorus above which the risk of total mortality increases, as well as a threshold for the phosphorus density of the food above which total and cardiovascular mortality increases. The reason for these associations is not clear, but phosphorus is found in high concentrations in meat and soft drinks, and so may simply be a marker of a low quality diet. Soft drinks in particular are low quality foods because they are high in sugar, and so high intakes of phosphorus might be associated with higher intakes of sugar and the detrimental metabolic effects that sugar produces.
Dr Robert Barrington’s Nutritional Recommendation: High intakes of phosphorus may therefore be problematic, assuming the phosphorus is the cause of the association. It is likely that the 1400 mg threshold for the increases in mortality would be altered if the calcium intake was increased as with minerals it is the ratios that are important, not the absolute intakes. A phosphorus intake of 1400 mg per day would require a calcium intake of 2800 mg per day to maintain the correct balance and studies suggest that most individuals in Western nations obtain nowhere near this amount. The best way to maintain a correct phosphorus to calcium ratio is to eat a mainly plant based diet. Plant foods supply minerals in ratios that are much closer to the ideal ratios required by humans for correct metabolism. As soon as plant foods are neglected and Westernised foods substituted, these mineral ratios change unfavourably and ill health results. Good sources of calcium include milk, seeds, tinned fatty fish, vegetables and nuts.
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