A diverse diet strengthens the immune system. By focusing on just a few simple questions, we can learn to control our appetite, avoid becoming overweight, and stay healthy.
A tour of the meal of the 21st century – between personalized nutrition and futuristic food-powder
Imagine your personalized daily diet, served in a capsule. This futuristic project was launched a few months ago by about fifteen researchers from the Nestlé Institute of Health Sciences (NIHS) in Lausanne. Code name: Iron Man.
Their idea? To design a device able to assess any individual’s nutritional deficiencies and concoct a personalized blend of vitamins and essential minerals in response. Inspired by the food synthesizer featured in the TV series Star Trek, this nutritional Nespresso is one among many examples of research projects seeking to develop personalized nutrition: to each, his or her customized diet. We are not all equal before our food. Certain products may be recommended based on an individual’s profile (healthy, obese, diabetic, etc.) but also on his or her age and gender.
“Because of our genetic heritage, we metabolize foods differently,” explains François Pralong, director of the Department of Endocrinology at the CHUV and professor at the Faculty of Biology and Medicine at the University of Lausanne. Some individuals may, for example, be more sensitive than others to a given amount of salt. And the same holds for any other type of micronutrient (vitamins, minerals, etc.) or macronutrient (proteins, sugars, fats).
1- Age and gender differences
Children require more vitamins,
mineral salts, and calcium. The elderly should generally cut back on salt but take in more vitamin D, calcium, and sufficient proteins. Even more so, given their tendency to lose their appetite and their sense of taste, which makes them eat less and lose weight and muscle (cachexia). Because they have sufficient pent up reserves, healthy adults need less mineral salts, vitamins, and calcium. Because of their menstrual cycle, women should consume more iron than men, and after menopause, they should boost their calcium intake to reduce the increased risk of osteoporosis.
That being said, there are, of course, rough guidelines that are valid for everyone. The nutritional pyramid (by order of importance: drinks, fruits and vegetables, grains, dairy, meat, fish, fats, end finally sweets, snacks, and alcohol) continues to be useful. And a diet rich in fat, e.g. fast food, delays satiation, making us all the more likely to indulge.
2- Avoid frustration
A healthy diet further helps fortify the immune system. “For a healthy subject, the best immunity comes from a balanced, varied diet that favors fruits and vegetables, plant-based fats, fish, poultry, and white meat,” says Pauline Coti Bertrand, who directs the Nutrition Clinic at the CHUV. “That doesn’t mean other foods should be excluded. What matters is their relative frequency. For sick individuals, supplements can be considered as a way to address the needs that are caused by their illness. Most importantly, they should keep their weight as close as possible to their healthy weight, and move.” The problem is different for people suffering from a disease, such as obesity. “Today, we no longer resort to diets,” says François Pralong. “We observed that restriction leads to frustration, which inevitably leads to relapses.” This phenomenon, known as yo-yo dieting or weight cycling, is extremely unhealthy, as it involves a decrease in lean body mass (muscle) and successive gains in fat, which, after three to five cycles over ten years, can result in a very unfavorable metabolic profile and open the door to insulin resistance, diabetes, or hypercholesterolemia.
3- Control your appetite
Over the past years, science has brought to light a plethora of hormones that control appetite. Despite that, we are still far from developing treatments that regulate hunger. This explains the interest in psychological approaches. Marion Linda is an assistant psychologist at the Consultation for the Prevention and Treatment of Obesity at the CHUV. From a psychological perspective, she says that a healthy diet involves “a clear emotional identification of bodily sensations” and, more generally, the capacity to manage one’s emotions.
“It’s a matter of expanding our awareness of the mechanisms behind food consumption,” says François Pralong. In other words, addressing the question: why do we eat? We may eat because we are hungry, stressed, or to compensate, out of desire, frustration, or for want of anything better to do. The goal is to slightly change our nutritional habits, keeping in mind certain dietary guidelines on the composition of a healthy meal (nutritional pyramid) and its size: no second helpings, chew and eat slowly to allow the feeling of satiation to keep up (see interview on page 26).
Over six to ten months, the initial goal is to stabilize the patient’s weight, before aiming to drop it by about 10% over one or two years. This can be disappointing, especially for people who are very overweight. And of course, physical activity is at least equally, if not more, important. “Ideally, this involves between twenty and thirty minutes of physical activity a day, intense enough that you break a sweat, but what you do and when you do it doesn’t matter,” says François Pralong. “Even ten minutes a day can be enough to reduce cardiovascular risks.”