A diet high in carbohydrates is associated with a higher risk of death than a diet high in fats. That is the outcome of an international team of researchers. However, this conclusion requires some context.
Carbohydrates or Fats?
I recently dedicated an article to the horror documentary “What the Health.” Some of the remarkable statements in that documentary about the food industry came from doctors who reported that there’s nothing wrong with carbohydrates. It’s mainly fats, animal fats, that cause health problems like diabetes. Surgeon Garth Davis, for example, says that the idea that you get fat from carbohydrates is ridiculous and that the risk of diabetes is actually reduced if you eat more sugars.
“Sugars cannot be converted into fat!” To which he quietly adds, “Unless you really eat too many calories…”
Apparently, many people do eat too many calories. A possibility that doesn’t seem entirely unfamiliar to me.
Other doctors in the documentary point out the increased risk of fat accumulation and thus the risk of heart disease, strokes, and ultimately death with a high-fat diet. However, recent research by an international team of researchers leads to the opposite conclusion.
This kind of discussion always needs to be placed in the right context. In the case of “What the Health,” it’s useful to know that this documentary may well be called vegan propaganda. In the case of the recent research claiming the opposite, the question arises as to how relevant it is for the average Dutch person.
In general, it can be said that it makes little sense to point to a single culprit.
The Research
For the international study, researchers used data from the Prospective Urban Rural Epidemiology (PURE) study. This is a population study of people aged 35 to 70 from 18 different countries who were followed for an average of 7 years. This provided insight into the diet of over 135,000 people based on questionnaires. The team of researchers (led by a researcher from McMaster University) primarily wanted to find associations between diet and the risk of death, both in general and specifically from cardiovascular diseases. Additionally, they looked for associations between diet and heart-related issues such as strokes. When establishing the association, known risk factors such as age, smokers, physical activity, and BMI were taken into account, but not total calorie intake, which I believe is a weakness in the study.
Participants were grouped based on the relative amount of macros they consumed daily. So, people who derived their energy to a higher extent from fats were grouped, as were those who received their calories to a higher extent from carbohydrates. They then looked at the effect of high intake of carbohydrates, total fat, and each type of fat on the mentioned points such as death and heart diseases.
The Results
Compared to the group of people who consumed the least carbohydrates, those who consumed the most carbohydrates had a 28% higher chance of death. However, the higher intake of carbohydrates was not associated with a higher chance of death from heart disease.
People in the group consuming the most fat (total fat), averaging 35.3% of the total amount of daily calories, had a 23 percent lower chance of death compared to people in the group consuming the least fat. Also, when specifically looking at different types of fats, higher intakes of saturated fats, monounsaturated fats, and polyunsaturated fats were all associated with a lower chance of death. Higher fat intake was also associated with a lower chance of stroke. According to the researchers, guidelines for nutrition and the amount of fats in them should therefore be reassessed.
Remarks on the Research
Before we rewrite the books, however, some major caveats should be placed on this research.
Firstly, one might question whether this would lead to a different recommendation. The researchers advise getting 50 to 55 percent of your energy from carbohydrates and about 35% from fats. This corresponds to Dutch guidelines from, for example, the Health Council and the Nutrition Center.
Additionally, one might wonder to what extent these results are representative of Western European countries. Many of the participants in the PURE study come from low-income countries. Other studies that showed a correlation between higher fat intake and heart diseases were often conducted in affluent countries. The recommendation from those studies to reduce fats may be less relevant in countries where getting enough food is a greater challenge than getting the right food.
For example, when you think of countries like Bangladesh and Zimbabwe, both represented in the PURE study, you also have to consider that there is a greater dependence on refined sugars such as in rice. That has different consequences than, for example, the more complex carbohydrates found in whole grain bread. The researchers of the international team were aware of this and wanted to see how representative these findings are for non-Western countries.
And the winner is….
So, carbohydrates or fats for a healthier life?
Actually, it’s a ridiculous question.
The biggest problem in the recent international research is not the research itself or the conclusion. The problem lies mainly in the way it has been picked up by some media outlets. In many cases, we see similar titles as above this article, but without the question mark, the quotation marks, and the remarks in the introduction and the article itself.
Moreover, various media outlets draw from this the recommendation to increase the amount of fats, while it is highly likely that the average reader is already consuming the amount that falls within the high-fat intake group in the study.
Just yesterday, I wrote an article about the different responses of different people to the same diet. Some lose weight earlier by reducing carbohydrates, others by reducing fats. A general judgment about the effect of carbohydrates vs. fats is therefore actually impossible to give.
Finally, in practice, the problem nine times out of ten will not be caused by an incorrect ratio between fats and carbohydrates (and proteins). It will be more beneficial for most people to look at the amount of energy coming in and only then at the source of this energy.
References
- Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. Dehghan, MahshidDiaz, R et al. The Lancet
