Swapping processed foods made with refined grains for their whole grain versions can promote improvements in metabolic and cardiovascular health, affecting indicators such as blood pressure, triglycerides, glycemia, and cholesterol. However, a meta-analysis published in September in the European Heart Journal indicated that the effects on body weight and abdominal circumference are modest.
This investigation analyzed 87 clinical trials involving over 6,500 participants, aiming to measure the impact of whole grain consumption on cardiometabolic risk factors. Generally, the benefits became more noticeable when there was a daily intake of 60 to 100 grams of these foods by dry weight (before cooking or hydrating), which corresponds to about four to six servings.
Common examples of whole grains include oats, brown rice, corn, and whole wheat. During refining processes, the bran and germ are removed totally or partially, resulting in a decrease in nutrient and fiber content. Nutritionist Brennda Leal, from Einstein Israelite Hospital, clarifies that whole grains retain their three parts: the bran, which is the outer layer and rich in fiber; the germ, which contains vitamins, minerals, and fats and has the potential to generate a new plant; and the endosperm, the inner part, predominantly composed of starch and protein.
In contrast to refined grains, whole foods offer a higher amount of fiber and bioactive compounds, which aids both intestinal and cardiometabolic health. Fibers help regulate intestinal transit and can promote a feeling of satiety, in addition to interfering with cholesterol absorption. According to Leal, oats, for example, contain beta-glucans, fibers linked to lowering LDL cholesterol levels in the blood, an excess of which increases cardiovascular risk and facilitates cholesterol accumulation in the arteries.
Despite the positive findings, the nutritionist warns that not all whole foods have identical effects, as their composition varies. She emphasizes that the benefits are tied to the specific type of grain and the overall composition of the food.
The meta-analysis revealed that every 48-gram increase in daily whole grain consumption (by dry weight) was associated with an average drop of 0.20 kilograms in body weight and 0.22 centimeters in waist circumference. Reductions were also observed in total cholesterol, LDL, triglycerides, fasting glycemia, and systolic blood pressure.
Although the data indicates advantages in various markers, the average changes were small, which prevents the conclusion that simple substitution is sufficient to prevent diseases or promote weight loss. Brennda Leal reinforces that consuming more whole options primarily contributes through increased satiety and nutritional quality, but does not constitute an isolated solution for weight loss, requiring consideration of the entire dietary habits and lifestyle.
It is important to note that ingredients like rice absorb water during preparation, increasing their weight. Furthermore, serving equivalence differs depending on the food, making standardized conversion to spoons of rice, slices of bread, or servings of oats difficult. The recommendation of 60 to 100 grams daily should not be seen as a universal guideline. The Einstein specialist points out that nutritional goals must be personalized, as the ideal amount depends on each individual's clinical conditions, age, energy needs, eating habits, and digestive tolerance.
For those accustomed to consuming mostly refined products, the transition can be gradual, for example, substituting white rice with brown rice, refined flour bread with a whole grain version, or regular pasta with whole grain pasta. Another suggestion is to incorporate oats into smoothies, porridges, or fruits. When purchasing processed products, it is crucial to check the ingredient list and compare the content of sodium, added sugars, and fiber, remembering that they are listed in descending order of quantity. If whole wheat flour is listed first, it signals that it is the main component. On the other hand, if the first item is wheat flour (or 'wheat flour enriched with iron and folic acid') and whole flour appears further down, it indicates a higher proportion of refined flour in the product. Brennda Leal warns that the dark coloration of the food, by itself, does not guarantee that the bread is whole grain.
