Grains such as millet, wheat, rye barley, sorghum and spelt are the seeds of grasses, and these carbohydrate and fibre rich foods play an important role in human nutrition. Nutritionally grains are low in lysine, and this makes them an incomplete protein, however despite this fact, much of the World’s population relies on grains as an important food source. The use of grains dates back to early civilisation, and historical evidence suggests that grains are pivotal in allowing the formation of civilisation. The milling of grains to produce bread was originally a simple process that ground the whole grain into flour, thus the final product retained all of the nutrients present in the original grain. However, more modern processing techniques have allowed the removal of the germ and bran layers of the grain to leave a purer product composed of mainly the starchy endosperm. Refining the flour in this way removes most of the micronutrients and fibre from the grain however, as these components are present largely in just the bran and germ layers.
Evidence is accumulating to suggests that consumption of refined grains is a cause of Western lifestyle disease. In particular, the lack of fibre causes detrimental blood sugar effects, and this causes liver overload syndrome, a process by which too much energy is delivered to the liver in too short a period of time. This switches the metabolism of the liver such that the de novo lipogenesis pathway becomes increasingly active, and the resultant fatty acids accumulate in tissues and cause insulin resistance. In addition the micronutrient poor refined flour increases the risk of micronutrient deficiencies, some such as chromium and zinc may contribute to the deterioration of the insulin signal pathway. Many studies have investigated the effects of whole grain consumption on body weight and body fat. A recent study published in the American Journal of Clinical Nutrition analysed the data from these studies in a meta analysis1 to determine if whole grain consumption was associated with improvements in body composition.
The results of the study showed that whole grain consumption was not associated with a change in body weight from the data in the 26 studies included. However, a small decrease in body fat was associated with whole grain consumption. This decrease in body fat was roughly 0.48 % for those who consumed whole grain in comparison to those who consumed refine grains. This result is interesting because if the body weight remained unchanged but body fat was reduced, this means that lean mass must have increased. Therefore that the body composition improvements seen with whole grain consumption are consistent with a reversal of an insulin resistant state, which would allow for increased skeletal muscle protein synthesis and increased skeletal muscle glycogen storage which would both increase lean mass. At the same time the reduction in body fat suggests that adipose tissue levels are being used as a source of energy, and this likely results from a fall in fasting insulin levels.
Dr Robert Barrington’s Nutritional Recommendation: Eating whole grains is a pivotal part of consuming a high quality diet. Refined grains lead to weight gain through their detrimental effects of insulin sensitivity and the slow decline to abdominal obesity and Western lifestyle diseases is a direct result of consuming a poor quality diet containing refined grains. All grains included in their diet should be in their whole grain form. The only exception to this rule is the use of a limited amount of refined grains immediately following physical activity.
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