Every now and then a new "forbidden" food appears, a supposed superfood, a diet that promises to revolutionize our health or a nutritional myth that circulates strongly again. And science has been showing for years that nutrition is much more complex than a handful of viral rules or demonized foods.
In fact, nutritionist Javier Martínez, author of 'The power of eating well' (Espasa), insists that the true impact on health does not depend on a specific ingredient, but on the set of habits that we maintain over time. In an interview with 20Minutos, he dismantles some of the most widespread nutritional myths and explains what the scientific evidence really says.
The biggest mistake: believing that a single food determines our health
The dietician-nutritionist considers that the biggest nutritional myth is thinking that a food, by itself, can explain our weight or our state of health. "For years we have been looking for culprits: first it was fats, then bread, pasta, fruit, milk or carbohydrates. But science has been showing for decades that our health does not depend on an isolated food, but on the eating pattern and the set of habits that we maintain over time," he comments.
The nutritionist remembers that foods do not act in isolation, but within a "food matrix." Therefore, consuming the sugars present in a piece of fruit, accompanied by fiber and vitamins, does not have the same effect as drinking them in a soft drink. Eating fresh meat is also not comparable to processed meat.
In addition, he points out that today we know that other factors influence, such as the degree of food processing, the eating pattern, packaging or even certain environmental contaminants. For Javier Martínez, another common mistake is to reduce food solely to calories.
"Nutrition does not work in black and white; it works with scientific evidence and consistency," and summarizes the importance of habits with a very simple reflection: "Health does not depend on what we do during the month of August on vacation, but on what we do between September and the following summer."
Do carbohydrates at night make you gain weight?
There has been so much talk about carbohydrates and they have been accused of "gaining weight" if consumed at night, that Javier Martínez has left a space in his book to clarify everything: And his answer is clear: no. "Weight gain depends mainly on the energy balance maintained over time, on our physical activity and on the overall quality of our diet, not on consuming carbohydrates at night."
According to the expert, maintaining regular meal times, respecting circadian rhythms and avoiding very heavy dinners seems to have more impact on metabolic health than eliminating a specific nutrient. "In fact, foods such as legumes, potatoes, brown rice or quality bread can perfectly form part of a healthy dinner," he says, adding that "some studies even suggest that a balanced dinner that includes complex carbohydrates can promote rest by facilitating the availability of tryptophan for the synthesis of serotonin and melatonin, although this effect depends on the overall context of the lifestyle."
Neither the fruit ferments nor the egg is the enemy
Another widespread myth is that fruit ferments if it is eaten for dessert, and the expert flatly denies it: "Fruit does not ferment in the stomach. There is no scientific evidence that eating fruit before, during or after meals modifies its digestion, its nutrients or its health benefits," he says. In fact, remember that greater fruit consumption is associated with a lower risk of cardiovascular diseases, type 2 diabetes, some types of cancer and premature mortality.
For this reason, he insists that "the best time to eat fruit is the one in which you manage to eat more fruit." Something similar happens with eggs. For decades they were singled out for their cholesterol content, but current evidence has changed that view.
"In most people, the cholesterol we eat has a much smaller impact on blood cholesterol than factors such as the overall quality of the diet, excess saturated fat, sedentary lifestyle, smoking or genetic predisposition," says the expert. And it highlights that the egg provides high-quality proteins, vitamins, minerals and compounds beneficial for eye health. His message is clear: "For years we blamed the egg while the real problem grew silently: the excess of ultra-processed foods; it would be better to eat more eggs and less sausages and processed meat."
If you don't have an intolerance, why do you eliminate lactose?
On the other hand, there are those foods that disappear from the diet without being necessary, as occurs for example with lactose. The specialist is against these habits: "Eliminating lactose without a diagnosed intolerance has not been proven to provide health benefits." In addition, removing dairy products without planning can reduce the intake of calcium, protein, vitamin B12 or iodine. And something similar happens with people who live with abdominal bloating or gas and begin to eliminate foods on their own.
As he explains, very different causes can be found behind these symptoms, from constipation or stress to digestive disorders or specific intolerances: "Many people do not need to eliminate foods; they need a diagnosis and personalized treatment."
Is there one sugar better than another?
Regarding sugar, another of the topics that Javier Martínez addresses in his book and in this interview, if there is one better than the other, the expert believes that the question is poorly posed. "Rather than looking for a 'healthier' sugar, we should get our palates used to needing less sweetness." Explain that brown sugar, panela, coconut sugar or agave syrup have a metabolic effect very similar to white sugar when consumed in normal quantities. Honey contains some beneficial compounds, but it also provides free sugars and should be consumed in moderation. As for sweeteners, they can be useful in some cases to reduce sugar consumption, although they do not replace a healthy diet.
