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Very low carb diets - good or bad?

Posted on December 6, 2019 at 5:20 PM

According to a leading Australian food and nutrition scientist, very low carbohydrate diets should be avoided because there is convincing evidence for a detrimental effect on health.

Citing results from a large meta-analysis published in European Heart, Dr Emma Beckett says the data show that people who consume a low carbohydrate diet and reduce their intake of fibre are at greater risk of premature death. They are also at increased risk for individual causes of death including coronary heart disease, stroke and cancer. The study sheds new light on the dangers of long-term low carbohydrate diets, says Dr Beckett, a molecular nutritionist at the University of Newcastle. Specifically, it found that the overall risk of death from any cause was 15% higher in people who consumed the least amount of carbohydrates, the risk of cardiovascular death was 13% higher and that of dying of cancer was 8% higher. The reduced intake of fibre and fruits and increased intake of animal protein and saturated fat with these diets may play a role, according to the study. Similar results from a series of systematic reviews and meta-analyses reported in The Lancet suggest a 15-30% decrease in all-cause and cardiovascular related mortality when comparing people who eat the highest amount of fibre to those who eat the least. Eating fibre-rich foods also reduced incidence of coronary heart disease, stroke, type 2 diabetes and colorectal cancer by 16-24%. Dr Beckett says the evidence is already reflected in the latest Australian dietary guidelines but “the real problem is that most people don’t follow them”. “The guidelines are already specifically worded for recommending high quality carbohydrate sources from grain cereals – mostly wholegrains – along with fruit, pulses and vegetables, and reducing low-quality carbohydrates from discretionary foods,” she says. “The biggest problem is that we are not doing well at communicating this. About 50% percent of our energy needs should come from high-quality carbohydrates, 30% from fats and 20% from protein but most Australians think they need to eat more protein.” While the evidence shows that a low-carb diet can aid in weight loss, Dr Beckett warns of the “short term win of losing weight with the long-term consequences of missing out on important nutrients”. She says there is strong evidence that grain fibre in particular has a profound effect on health due to its effects on gut microbiota. A recent systematic review of 42 studies found 39 demonstrated an increase in microbiota diversity and abundance following consumption of wheat and other grain fibres as prebiotics. Potential health benefits include improved immunity and gut function, reduced inflammation, reduced risk of obesity and type 2 diabetes and potential protection from bowel cancer. There is also evidence of improved cognition and mood, according to the study. “If we are going to recommend people change their carb intake, we have to talk to them about the importance of fibre in foods because there is no evidence for fibre supplements,” Dr Beckett says. “Just your normal fruits and veg and your standard high fibre breakfast cereals and wholegrain bread are fine. You don’t need to eat mangosteen and quinoa to be healthy.”

AusDoc 22nd October 2019

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