Quest Vitamins LTD, |
Following a low carbohydrate diet may impair mental function
The Atkins diet revolutionised our approach to dieting; suddenly it was bread, not butter,that became the enemy of the waist line. Since the publication of the diet researchers and professionals have highlighted it's pitfalls; a far more sophisticated and balanced approach to the role of carbohydrates in a healthy diet has been developed via the glycaemic index. Nonetheless cutting out carbohydrates remains a very popular method of shedding extra weight. New research has found that this way of eating may make or may not make you slimmer, but you may be left wondering why you wanted to lose weight in the first place.
19 women aged 22-25 chose to follow either a low-carbohydrate or a reduced-calorie balanced diet similar to that recommended by the American Dietetic Association. Nine chose the LC diet, which restricted carbohydrates to no more than 20 grams a day. Seventy-two hours before beginning their diets and then 48 hours, 1, 2, and 3 weeks after starting, the women completed cognitive tasks assessing memory, vigilance, attention and mood. Results showed that during complete withdrawal of dietary carbohydrate, low-carbohydrate dieters performed worse on memory-based tasks than ADAdieters; these impairments were ameliorated after reintroduction of carbohydrates.
Click here to read the study.
Interestingly however the study also found that the low-carbohydrate dieters reported less confusion and responded faster during an attention vigilance task than the ADA dieters. This is contrary two previous studies. The first of these found that participants consuming a low carbohydrate, high fat diet made significantly less improvement over the study period in the time taken to respond to stimuli than did those consuming a conventional high carbohydrate, low fat diet. An earlier study found that performance of a complex, cognitively demanding task assessing mental flexibility was significantly worse after the consumption of a very-low-energy, low carbohydrate diet.
The brain has an absolute requirement for glucose but is unable to use protein or fat as a source. Low-carbohydrate diets stimulates the synthesis of ketones to spare muscle protein, which would otherwise be broken down in the absence of dietary glucose. During prolonged periods of starvation, fatty acids are made from the breakdown of stored body fat; these free fatty acids are converted to ketones by the liver to satisfy the brain's energy requirements. Ketogenic diets are used to manage epilepsy and are known to influence brain function profoundly.
This study used a very extreme one week regime of no carbohydrate intake at all. The message is, as always, moderation. There is very little remaining doubt that improving the quality of carbohydrate consumed and reducing overall carbohydrate intake while increasing essential fat intake will have a dramatic positive impact on health; on the other hand dramatically lowering carbohydrate intake can be detrimental to health. |