I'm not sure I'm adding to the sum of human knowledge here but every week I write a social media blog for my non-diabetic contacts to raise awareness of T2 in particular. Having been an advocate of Low Carb diets, this week I thought I needed to address this study. You may or may not agree with the everything I've written, but bear in mind my audience is non-diabetics whose attention span to matters like this is naturally shorter - so I limit myself to fewer than 1000 words even though there is so much more to say. My post was as follows:
STUDY SUGGESTS OWNING LABRADORS INCREASES RISK OF BLINDNESS
Hello, in this week’s T2 diabetic blog (ignore if it’s not for you, thank you for those that read and comment), I address a couple of news stories from this week.
Firstly, having recently embarked on and advocated a low carb diet, I was slightly alarmed to read and hear a BBC headline on Friday about study that suggests low-carb diets apparently shorten life expectancy by about 4 years.
Never rely on the media article, always get to the source evidence. So I followed the link and read the published study in The Lancet. (link in comments below)
I’ll leave it up to you if you decide to read the study yourself – I am obviously biased so don’t take my word for anything. Here though are my observations on the study:
DON’T BELIEVE EVERYTHING YOU READ IN THE PAPERS
First up, the study’s conclusions do not support the sensationalist BBC Headline of Low Carbs lowering life expectancy provided carbs are replaced with plant based proteins and fats, rather that just animal ones. In fact, here are the very final words of the study, the last verbatim message that the reader is left with to ponder:
“When restricting carbohydrate intake, replacement of carbohydrates with predominantly plant based fats and proteins could be considered as a long term approach to promote healthy aging.”
Well that’s a bit of a different final message isn’t it? And not surprisingly one that most deliberate low carb eaters already know – don’t just stuff yourself with meat and cheese, you need fibre too: and it doesn’t take 25 years to work that out. Lots of green veg, nuts, seeds, and some fruit are essential to a healthy low carb diet – and the study suggests that this approach is healthier than any carb based diet. The study also concludes that diets containing high carbs are more dangerous – it concludes that carbs are good provided only taken in moderation, which is fine except large proportions of the population have no flipping idea what moderation means, hence rising levels of T2.
The BBC however decided to print a story about the study being an attack on all low carbs: I’m not blaming them: it is a polarised debate and the media love to play both sides: leaving the public confused in the middle and at the mercy of advertisers and food producers feeding them a diet of rubbish that they like to eat but is contributing to an ever growing obesity and diabetic crisis.
But is the study itself any good? is it actually telling us anything?
SCIENCE: BUT NOT AS WE KNOW IT.
Having established that the study conclusions are not as stark as the BBC suggests (in fact quite the opposite) I could stop there. Maybe I should.
Any study of long term effects of diet on populations are inherently flawed because it is impossible to collect data which is both scientifically and ethically sound (to do it properly would involve knowingly placing people in harm’s way for lengthy periods).
This study chose good ethics over good science and that is OK, but the science is very flaky. The study itself acknowledges its own limitations (note the BBC ignored these caveats):
- the study claims to cover a 25 year period. All they really did was to invite the subjects to complete a food questionnaire in year 1 and year 6 and then extrapolated the mean results over the remaining 19 years, assuming no change in behaviour over that time.
- It was not a clinical trial. It relied on people filling in a questionnaire of estimated food consumption – not even a food diary, but a snapshot opinion.
- It then measured who was still alive in year 25. It didn’t examine cause of death but drew associations between estimated diet over that period and rate of mortality.
Anyone see any problem with that methodology and its chances of gathering accurate data, and then drawing accurate conclusions from it?
Its findings measure correlation not cause. When you measure correlation you automatically take two massive risks:
1) that you conclude correlation between two things that are not actually co-related (eg the famous case of the correlated data of people killed in US swimming pool accidents versus the number of films released by Nicholas Cage).
2) That you conclude correlation, but get cause and effect the wrong way around (eg owning a labrador increases the risk of being blind)
Putting that into context, remember that a lot of people only start a low carb diet because of a health event in their life such as (in my case) a T2 Diabetes diagnosis, or sadly, diabetes complications having followed years of bad advice to keep eating carbs. Very sadly, by that point , for a lot of patients, quite a lot a damage has been done already – I’m one of the lucky ones.
As a Type 2 Diabetic I know that I live in a state of carbohydrate intolerance – therefore a low carb diet definitely improves my individual long term mortality risk: it doesn’t mean I’ll necessarily live longer than average – I can’t know that. The same is true of any T2 or insulin resistant adult (combined that’s c50% of people by the way).
KIDS WITH COMPLICATIONS
And the other story hitting the headlines this week is of the ever invasive reach of our diabetic and obesity crisis – that there has been a 40% increase in children being diagnosed Type 2; that there are 22,000 seriously obese children in the UK, that half of all new diagnoses of Type 2 are under the age of 35. That is real data, and points to a real problem. Maybe our society, our media and our government need to focus on fixing that.