Dietary carbohydrate intake and mortality: a prospective cohort study (Lancet)

[Mattie]

Both high and low percentages of carbohydrate diets were associated with increased mortality, with minimal risk observed at 50–55% carbohydrate intake. Low carbohydrate dietary patterns favouring animal-derived protein and fat sources, from sources such as lamb, beef, pork, and chicken, were associated with higher mortality, whereas those that favoured plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter, and whole-grain breads, were associated with lower mortality, suggesting that the source of food notably modifies the association between carbohydrate intake and mortality.

https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30135-X/fulltext

 

[Amw66]

Self reported questionnaires .....

 

[Milo]

Carbs are not bad for us. What is bad is extremism, eliminating a whole food group. I heard someone telling about her doctor recommendation (a doctor specializing in ME and similar diseases) of ketogenic diet, and I cringed. We have no good evidence. The metabolomics study is a scientific in vitro study. I am not convinced that because the citric acid cycle does not work well we should not have any carbohydrates at all. In order to conclude this, further research and scientific publication is needed. These hypothesis need to be tested, preferably with a large number of people, possibly in a controlled setting.

 

[sb4]

@Milo It depends on the individual, but I think it is worth it to recommend everyone to at least try ketosis or VLC and see if it helps or not. So I think that docs advice is good.

Personally my heart pounding is far worse with carbs and several people on the forums have gotten great improvement from keto, as well as with other diseases. Some people have gotten benefit from very high carb.

I tend to have the opposite opinion, that being the extremes are where you have the highest chance of benefit. If I was to put it very simplistically I would say it's easier on your metabolism to have either very high fat vlc OR very high carb vlf. Niether of which are in the study.

 

[Ravn]

While the media predictably have jumped on the high versus low carb issue what the study actually shows (ignoring for the moment other issues such as self- and infrequently reported diets and all sorts of confounding factors) is this:
low carb with lots of meat = bad
low carb with lots of plant foods = good
In other words, whatever your macro nutrient preference, always eat your veges. Now there's an original idea

Low carbohydrate dietary patterns favouring animal-derived protein and fat sources, from sources such as lamb, beef, pork, and chicken, were associated with higher mortality, whereas those that favoured plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter, and whole-grain breads, were associated with lower mortality

 

[NelliePledge]

does any low carb diet really suggest replacing all the carbs with meat?? I eat more eggs and probably a fair bit more meat and dairy (goat/sheep not cow) than last year and my cholesterol and triglycerides have both reduced more than 15%. going low carb has increased my veg intake carbs I eat are veggies and pulses.

 

[Hutan]

While the media predictably have jumped on the high versus low carb issue

Yes, the tv news here has been a perfect example of sensationalising and misinterpreting findings. They somehow got this out of the report:
'Eating bread, pasta and potatoes can add 4 years to your life!!!'

The report has been discussed a bit on the ketogenic diet thread here. (scroll down the page to post #232)

 

[NelliePledge]

Yes, the tv news here has been a perfect example of sensationalising and misinterpreting findings. They somehow got this out of the report
'Eating bread, pasta and potatoes can add 4 years to your life!!!'

The report has been discussed a bit on the ketogenic diet thread here.

this really is fake news

 

[alicec]

Their own disclaimers.

There are limitations to this study that merit consideration. This study represents observational data and is not a clinical trial; however, randomised trials of low carbohydrate diets on mortality are not practical because of the long duration of study required.

Another limitation of this study is that diet was only assessed at two time intervals, spanning a 6-year period, and dietary patterns could change during 25 years.

And as already noted, dietary assessment was by self-reported questionnaire - a notoriously unreliable method.

So yet another poorly designed nutritional study whose conclusions can't be relied on because of many possible confounders. Why do they keep doing them and why do journals publish them?

 

[alicec]

Here is a very thorough analysis of the many defects of this particular study and of the limitations of nutritional epidemiological studies in general. Here is another consideration of the general problem of these types of studies.

 

[Alvin]

I am unable to read the whole study but meat is not the only game in town, what if it were replaced by more vegetables instead. Also what meat or what vegetables, if the predominant meat was say pork but turkey is the ticket then this study would end up suggesting that carbohydrates are superior when in fact they just used the wrong meat(s).

 

[Hutan]

Here is a very thorough analysis of the many defects of this particular study and of the limitations of nutritional epidemiological studies in general.

Worth a read. The more I read of scientific studies, the less I trust any scientific finding that makes a headline in a popular magazine.

And as already noted, dietary assessment was by self-reported questionnaire - a notoriously unreliable method.

From the article alicec recommended:

"If you only look at one reference, please let it be this one – there’s nothing like seeing a [Food Frequency Questionnaire] first hand. As you can see, there were nine possible responses, ranging from “never” to “six or more times a day.”

Can you remember what you ate last year? How standard were your portions? Did you have 5-6 ‘pats’ of butter a week or did it tip over to 1 a day? What’s a pat anyway? Did your diet then stay the same for 20-25 years?"

and

We know that there is something seriously wrong with the FFQ data in this paper because of the average calorie intake in the characteristics table. The characteristics table splits the 15,428 people into five equal groups (quintiles) from lower carb intake to higher carb intake. The calorie intake ranges from 1,558 calories per day in the lower carbohydrate quintile to 1,660 calories in the middle carbohydrate intake group. No group apparently consumed more than an average of 1,660 calories a day in this American study in the past 25 years. Really?!