The Western diet is devoid of meaningful levels of many of the essential micronutrients. In particular zinc is often highlighted as being deficient from the diet of many Westerners. Studies analysing zinc status do show that known biomarkers for zinc intake are often low or borderline deficient in many individuals living in Western nations. However, it is amazing that severe deficiencies are not present based on the incredibly mineral poor diets most Western individuals consume. The reason for the better than expected zinc status in many is simply due to the efficiency at which the body is able to extract minerals from food when required. Generally as the mineral content of the diet increases, fractional absorption rates fall to protect the body from accumulating too much of a particular mineral. As the mineral content of the diet falls, there is a large upregulation in the fractional absorption rates and a concomitant fall in the excretion rates in order to maintain adequate mineral status.
The changes to the absorption rates of zinc have been well studied in the nutritional literature using zinc of various doses. Such studies often use radiolabeled zinc in order to allow the movement of the zinc to be accurately followed between compartments in the body. For example, in one study1, researchers fed healthy young men 15 mg of zinc per day in their diet and then administered different intakes of zinc as radiolabeled zinc chloride amounting to 4.25 mg, 6.47 mg or 25.52 mg of zinc. The absorption rates from these doses were 81, 67 and 61 % with increasing intakes of zinc, respectively. Then the authors decreased the dietary intake of the subjects to less than 2 mg and repeated the administration of a radiolabelled zinc tracer. This resulted in an increase in the fractional zinc absorption of a 1.19 mg dose of radiolabelled zinc chloride from 81 to 92 %. This increase in zinc absorption was also evident when a tracer dose of 4.76 mg of zinc was administered to the subjects.
Therefore as zinc intakes fall it is likely that fractional absorption rates increase to compensate. This suggests that the fractional absorption rates of those consuming the typical Western diet is very high and that this high absorption rate compensates for the low intakes of zinc. In contrast, those eating a high quality diet and perhaps supplementing with a multivitamin containing zinc may have lower fractional absorption rates. This is not to say however, that supplementation and a high quality diet are pointless. Clearly even the high fractional absorption rates seen in those with a poor diet are not able to maintain optimal zinc levels. In fact the high fractional absorption rates likely prevent such individuals developing full mineral deficiencies, but instead allow the individuals to live in a state of mineral insufficiency. Such insufficient states are becoming increasingly common amongst Western populations, typified as they are by subclinical symptoms that are often difficult to detect or diagnose.
Dr Robert Barrington’s Nutritional Recommendation: The typical Western diet provides little in the way of meaningful levels of the essential micronutrients. However, the chronic low intake of micronutrients is compensated for by increases in the fractional absorption rates of the nutrients. This creates a limbo state between disease and health that leads to the development of subclinical disorders with no apparent cause.
RdB
