But one size does may fit all when it comes to diet and diabetes.
Long-term low-carb diets have no benefit for glycaemic control in type 2 diabetes patients at a population level, a new round-up of research has found.
Despite this, they may still be worth investigating for individuals, one expert says, given the variability among patients.
A systematic review from Japan found just six randomised controlled trials looking at the effects of long-term low-carbohydrate dietary interventions on HbA1c levels.
While they did find some benefits in treating dyslipidaemia, with an average 20% greater HDL cholesterol and 20% lower triglycerides on a low-carb diet, there was no significant difference between the intervention and control diets when it came to glycaemic control.
One of the studies under review, undertaken in Taiwan, did in fact show improvements in HbA1c levels from low-carb diets. The review authors write that Asian diets contain more carbohydrates than Western diets, that Asians have lower insulin secretion, and that “the risk of incident type 2 diabetes due to white rice consumption has been higher in Asians compared with Westerners … Therefore, we should consider the possibility that the effectiveness of LCD might vary depending on ethnicity.”
Overall, there were also no significant differences in weight loss, blood pressure or LDL cholesterol between low-carb and control diets.
RACGP diabetes chair Dr Gary Deed said the problem with such studies was the large variance among diets labelled “low-carbohydrate”, which could mean a moderate or an extreme reduction.
“The studies on it haven’t been normalised as to the amount of carbohydrate, which is makes it difficult to interpret,” he told TMR.
“Sometimes, lowering carbohydrate reduces blood glucose variability in a person. But one diet doesn’t fit everyone. That’s the take-home message: you can’t be prescriptive. It has to be something that’s culturally and individually appropriate and sustainable.
“Some people might benefit from a low-carbohydrate diet, but the change can be so significant that some people can’t maintain it.”
He said there was a risk of “mythology” building around the benefits of certain types of diets.
“You should always use an accredited practising dietitian to give the best evidence-based advice for that person.
“Being philosophically aligned to one dietary approach versus others … can be quite dangerous. You should be relying on someone who’s got the qualifications to analyse that person’s individual rules and requirements before allocating any particular dietary approach.”
