From cramps to flatulence: the unexpected side effects of energy bars

they are comfortable and fast-acting. The running fever, the push of high-intensity training and the obsession with diets have made energy bars an optimal resource for recharging energy, improving performance and recovering after exercise. It's logical, they're tremendously comfortable and their effect is clearly fast. But what if nutrition isn't the most important thing and they're just treats presented in a healthy wrapper? What need to use them if we do not compete at a professional level? And most importantly, in the face of an increasingly varied offer, do we know which one is right for us if we ultimately decide to opt for this food resource?

"Bars are an excellent source of carbohydrates, proteins, fats and fiber but, poorly used, they can have undesirable effects that can sometimes ruin a workout or competition," advances Luis Roberto Vergara, an internist at the University of Barcelona specializing in sports medicine. Since their nutrient profile is very variable and the needs of each athlete are unique, their first recommendation is to assess the nutritional composition, the rate of assimilation of carbohydrates and the added functional ingredients, as well as check if they have allergens and if they are suitable products for vegans.

It is also necessary to take into account something that does not appear in advertising: they can have unwelcome and unpleasant consequences, such as flatulence, cramps, swelling and digestive discomfort. It's a fiber thing. Colleen Tewksbury, a bariatric program researcher at Penn Medicine and president-elect of the Pennsylvania Academy of Nutrition and Dietetics in the United States, blames these effects on an excess of this compound. "Fiber slows down the absorption of sugar and cholesterol into the bloodstream, helping to keep LDL cholesterol levels low and stabilize glucose. He is a good health ally, but its contents in a bar are sometimes excessive, about 12 or 15 grams per serving," Self. said to the health journal Self. To get an idea, an apple contains about 4 or 5 grams and a slice of wholemeal bread doesn't go beyond the three. With the contents of an energy bar that Tewksbury points to, we can now cover half of the daily needs, which is about 14 grams for every 1,000 calories


In addition, physician Luis Roberto Vergara itdoes not consider it prudent to take fiber-enriched bars before playing sports due to the risk of diarrhea or intestinal discomfort. The problem is not oats or nuts that they may contain, but the added fibre used by manufacturers, sometimes extracted from chicory root, inulin, which is usually labeled with the name oligofructose and is included in the total fiber count, not separately. The FDA reports responsible for food and drug regulation, inulin and oligofructose protect the gut and balance it by stimulating intestinal flora. The danger is in the high quantity present in these products. "Our digestive system is not accustomed to it," says Tewksbury, who advises accompanying the bars with water to better digest the fiber


No sugar, but with laxative effect

Another precaution we should take when eating energy bars is the presence of polyalcohols, which are often used as artificial sweeteners in the food industry. They are a type of carbohydrate, but with fewer calories per gram than sugar . They are manufactured in laboratories from sugars, starches and fruit and vegetable extracts, and provide a sweet and clean taste. They also allow good baking and an appetizing appearance. The problem? Its contents are not clear on the label and sometimes it is so high that it ends up causing bloating, gas, cramps and diarrhoea, according to Tewksbury.

Even if it was well specified, its impact on the body will always depend on the composition of the gut bacteria in each individual, so each will respond differently. "In general," says Vergara, "in large quantities they can have laxative effects, although they are usually light and brief. The positive aspect is that, with carbohydrates being sugar-free, the increase in blood glucose is minimal.


With moderation and knowing how to distinguish what we need each time, the risks are not high, although the doctor insists on the information and on knowing the effects of their possible additives. "They usually come enriched with B-complex vitamins, vitamin C, magnesium, potassium, caffeine and creatine, with the aim of improving the performance and recovery of athletes. Let's not forget that, for example, caffeine can cause surge or arrhythmias and stress in the peripheral nervous system. Creatine, a molecule present in our muscles, strengthens our power and resistance to exhaustion, but it could worsen a kidney problem by the wear and tear that involves solubilizing it".

ne all energy bars are made with ingredients of equal quality. Some healthier include oats, inflated rice, seeds, dried fruits, nuts, olive oil or yogurt, for example, and less recommended ingredients include sugar, butter, hydrogenated oils, dyes, concentrated juices and chocolate. "The worst thing is that not always the labelling is as accurate as you would expect in a food product," Vergara warns. For example, the alert he launched in 2019 Health about energy bars made in Germany with traces of cashew, which were not indicated on the label. The Spanish Agency for Food Safety and Nutrition reported on another occasion the presence of nuts not declared in the composition of some energy bars.

Each bar has its own instruction manual

It is important to choose the product that best suits our expectations but, before doing so, Vergara remembers that we must take into account the type of activity and its intensity. "In the previous hours," he says, "a full bar can be consumed, with protein, fiber, fats and carbohydrates to prevent muscle fatigue. If we are going to practice an endurance workout, the bars with more slow-absorbing carbohydrates ensure optimal glucose levels. During a long or high-intensity competition or workout, it is ideal that it contains fast-absorbing carbohydrates, with hardly any fiber or protein. They are digestible and sugars pass quickly into the blood to preserve those levels and be used as a source of energy."

After physical exertion, the doctor's suggestion is to resort to energy bars rich in fast-absorbing carbohydrates and moderate absorption in proteins, fiber and fats, since they promote recovery. However, "despite its virtues," he clarifies, at no time should they be considered sufficient for proper nutrition and will not serve as an excuse to skip a meal. Its use is restricted to an addition to the diet harmonic and healthy of the athlete".

With children and adolescents, caution is even greater. One risk is that your blood levels of niacin, vitamin A and zinc will skyrocket. The Environmental Working Group reviewed some 2,500 types of breakfast cereals and energy bars, and found that, for these, about 30 brands had 50% more than the adult-recommended values of vitamin A, niacin or zinc. It is information to keep in mind, since, in high doses, these molecules can cause liver damage, in the case of vitamin A; skin rashes from excess niacin; inhibition of immune response, by elevated zinc levels.