By Jane, Aug 17 2018 09:15AM
If you are concerned by the headline on BBC today that suggests that low-carb diets could shorten life then here is my take on it.
The study was based on a questionnaire provided to a large number of people 25 years ago and repeated 19 years ago. It then measured their all-cause mortality 19 years later.
This is interesting material but it so a long way from being good research. Questionnaires are a notoriously bad way of measuring dietary intake; people recall badly, people exaggerate and people who care about their diet are more likely to record accurately. 25 years ago not many people cared much about their diet, except perhaps for vegetarians or other groups who took diet seriously and were more likely to make healthy choices.
25 years ago low-carb dieting was not popular or well documented, apart perhaps by Dr Atkins, and so the people who were labelled low-carb in the study were likely to be eating very differently from what is recommended on a low-carb diet today.
Also there is no measurement of whether these people’s diets might have changed over the subsequent 19 years. We know that diets have changed a lot over the last 2 decades, particularly for people who might have been on a higher fat & protein diet, in particular trans-fats have largely gone; whereas people who cared about their diet 25 years ago are more likely to care about it still, and hence more likely to still be alive.
And so the best way to summarise the report is by saying the people who ate a “low-carb” diets 25 years ago are more likely to have died since then than people who ate higher carb diets 25 years ago. If only we could go back in time and tell them!
To suggest that this means that higher-carb diets are more healthy than low-carb diets now would be quite wrong.
This report provides an association, with no description of the possible causes of the findings. 19 years later we have research from much better studies that shows that low-carb diets can improve health outcomes for most people, in particular by lowering obesity and reversing diabetes.
If you want to know more about this important subject please get in touch.