Why do the recommendations change?

Why do the recommendations change?

Eating appears recurrently in the media, since it is a common act that affects our health. However, every time a holder proposes changes in the recommendations of food consumptionmany people think: “If it is that each time they tell us one thing”.

Some examples of these lurches are those that occurred with the egg either the olive oilthat went from swell the black lists to be recommended. But why does this happen?

First of all, it should be noted that news about the results of a specific study is not the same as a change in a nutritional recommendation. These last ones do official bodies from numerous studies, and not based on a single work.

But sometimes a wide spread is given to isolated or preliminary investigations; for example, when conducting experiments prior to human studies, such as cell culture assays.

In any case, it is true that nutritional recommendations have been changing, and this is due to different reasons.

Discoveries, refocuses and rectifications

First, they sometimes identify phenomena that no one had detected before. This can be done with observational studies: research that collects information about the diet of many people and its relationship with health.

For example, about fifty years ago it was observed that the inhabitants of Africa ate considerably more fiber than Europeans and, at the same time, had fewer intestinal diseases. This finding was a starting point to conclude that the fiber was much more important in health than was thought.

Other times, investigators can refocus already known facts. Thus, it was known that certain plant compounds (the tannins) bind to proteins. Its properties were used to tan skins, a process that used the bark of trees rich in tannins.

[Olvida lo que sabías sobre las grasas: éstas son las nuevas recomendaciones alimentarias]

Much later, the researchers observed that also had health effects.since in our body they can bind to proteins such as those that metabolize carbohydrates, making us absorb sugars more slowly.

Sometimes errors are also recognized in investigations that had been done incorrectly.

For example, beneficial compounds of plant foods have long been investigated using the concentrations of the compound in the original food. However, it was later found that these compounds are transformed in our bodyand that concentrations in the blood are much lower than those in food. Therefore, the investigations had to be repeated using much lower concentrations.

Health goes by country

It can also happen that devices are invented to make new measurementssuch as the analysis of the intestinal microbiota. This has made it possible to observe that the Japanese have a bacterium that Western people do not have and that to come the fiber of the algae. For this reason, the Japanese do not take risks when eating dehydrated seaweed, whose high fiber content can be dangerous for other consumers.

Finally, there are nutritional recommendations that should be different in different countries or at different times. For example in In the US, it is recommended to consume much more calcium than in Spain. This is because there they take more phosphorus, a mineral that favors the elimination of calcium and, therefore, forces them to increase their intake of the latter.

On the other hand, a few decades ago Europe insisted on the consumption of certain vitamins to prevent diseases such as ricketsthat they were a public health problem. But at present, due to the characteristics of our population, eating patterns that have to do with diseases associated with aging prevail. That is to say, it is not that there is no need to consume vitamins, but right now there is more emphasis on other aspects.

The unjustified bad reputation of the egg

In the famous case of the egg, which went from villain to hero in the history of nutrition, several of the above factors were combined. First, various observational studies did not find that, with more consumption of this food, cardiovascular risk increased. And second, a greater biochemical knowledge allowed us to see that dietary cholesterol was not the most important factor to control the blood

This made it possible to state that the egg is healthy despite having a lot of cholesterol.

All of the above may lead some people to wonder if we can be sure that the nutritional recommendations we receive today will not change. That is a certainty that we cannot give.

against the ancient remedieswhere claims about its properties remain unshaken over time, nutritional research is always being updated. And although we are becoming more certain about certain aspects, at the same time there will be new observations, advances in methodologies or other approaches to known facts. And all this will produce criteria changes.

What we can be sure of is that, at all times, the best recommendation is offered based on the available evidence. And taking advantage of this for something as important as improving our health is within our reach.

The conversation

* Jara Pérez Jiménez is a Doctor in Food Science and Technology. Honorary Scientist of the Department of Metabolism and Nutrition of the ICTAN-CSIC, Institute of Food Science and Technology and Nutrition (ICTAN – CSIC).