t has been suggested that genetic factors are the cause of varying production rates of salivary amylase between individuals. However, an interesting study published in the Journal of Physiology in 19532 suggests that diet may be the overriding factor when it comes to determining the capacity to produce salivary amylase. Researchers investigated the capacity to produce salivary amylase in 90 Tswana of the Bechuanaland Protectorate, who consumed an almost totally carbohydrate based diet, 10 bushmen from the Kalahari who were carnivores, and 32 Europeans who consumed a mixed diet containing some carbohydrate with protein and fat. The mean salivary amylase production was 248, 95 and 22 units/mL saliva, for the Tswana, European and bushmen groups, respectively. However, when bushmen from the same tribe as above were tested after temporarily living on a mainly carbohydrate diet, their mean salivary amylase production increased to 95 units/mL saliva.
Therefore in normal healthy individuals, salivary amylase production may adapt to high dietary intake of carbohydrate rich foods. Interestingly when the bushmen consumed a more Westernised diet, their salivary amylase increased to similar level seen in Europeans eating a mixed diet. While ultimately it is the genes that direct the production of new proteins in cells, it is the environment that regulates the genes through interaction with the cell membrane. Epigenetics shows that factors such as carbohydrate intake can influence the genes within cells to regulate amylase production accordingly. The adaptation of the bushmen to a high carbohydrate diet is not surprising, as it would be inefficient for a cell to use a gene to produce proteins that were not required. Protein production is expensive, and limiting the resources wasted on new proteins that are not be required is the reason that genes can be switched off.
RdB
