Carbohydrate, protein and fat are macronutrients that provide the energy required for daily function in human nutrition. However, this energy cannot be released and expended effectively without the presence of additional factors in the diet. These factors, micronutrients, which include vitamins, minerals and antioxidant nutrients, are required for cellular function and without them disease is assured. Obtaining the correct amount of micronutrients is far more difficult that obtaining the macronutrients because while it is possible to see the macronutrients, it is not possible to visualise intakes of micronutrients. Understanding which foods these are likely to be present in is therefore important if health is to be maintained. Once effective route for the ingestion of important micronutrients is cereal grains. However, cereal grains must be in their original plant form, as processing grains removes many of these micronutrients. Carbohydrate quality therefore can be an important factor in micronutrient intakes.
For example, in one study researchers assessed the effects of dietary changes during pregnancy and how this affected micronutrient intake. In particular, the researchers assessed the total energy intake, starch, sugar, fiber intake, glycaemic index and glycemic load of pregnant women and correlated changes to these parameters with micronutrient intakes. The results of the study showed that total energy decreased in the third trimester and most women did not meet the minimum nutritional needs for folate, iron and dietary fibre from their diet. The changes in energy intake were positively correlated with changes to the intakes of all micronutrients. In particular the glycaemic load, the glycaemic index and total starch intake were inversely associated with micronutrient intake. These results therefore support previous data showing inadequate micronutrient intakes during pregnancy in Western populations and show that micronutrient intakes are dependent parameters of diet quality.
Dr Robert Barrington’s Nutritional Recommendation: A high glycaemic index, glycaemic load and total starch intake is consistent with low quality carbohydrate sources. As such low quality carbohydrates were associated with poor micronutrient intakes it is recommended that low glycaemic index carbohydrates containing a high fibre to starch ratio is consumed. Refining carbohydrates decreases their bran and germ layer components leaving just the starchy endosperm which is low in micronutrients. Interestingly in the study cited above, an increase in total sugars was associated with an increase in micronutrient intake. However, this may have reflected an increase in fruit intake, rather than an increase in the intake of refined crystalline fructose. Maintaining a diet containing carbohydrates with a low glycaemic index, providing a low glycaemic load, with a high fibre to starch ratio may improve health outcomes by providing an higher intake of micronutrients. However, fruit may also be beneficial in moderation.
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