Many wish for a long life - but only if you stay healthy in old age. What role can food play in this? And is there an age when it's too late to adopt a healthier diet?
The search for sources of eternal youth and longevity has accompanied mankind for centuries. At least for longevity, scientists believe they have found a very strong factor: the right diet. In contrast to genes or certain living conditions, it can be influenced. Increasingly, it is not only a question of what is put on the plate, in what quantity and quality - but also of when.
The US aging researchers Valter Longo and Rozalyn Anderson summarize the current state of knowledge in an overview article in the specialist journal "Cell". Friends of calorie bombs such as menus of burgers, fries and soda or comforters such as white chocolate now have to be very strong: The duo says that it is better to limit energy intake and fast more often in order to minimize the risk of illness and increase life expectancy.
They outline the core characteristics of what is probably the optimal form of nutrition - initially quite technically - as follows: medium to high intake of carbohydrates (45 to 60 percent) from high-quality sources; little but sufficient protein from mostly vegetable sources; 25 to 35 percent mostly plant-based fat.
Translated for everyday use in the kitchen, this means: "Lots of legumes, whole grains and vegetables; some fish; no red or processed meat and very little white meat; low in sugar and refined grains; good amounts of nuts and olive oil and some dark chocolate", says Longo according to a statement. It is optimal to only eat within a daily time window of eleven to twelve hours and to insert several fasting phases a year.
Longevity is Longo's life theme, so to speak: he is director of the Longevity Institute at the University of Southern California in the USA and author of several books. On his homepage he gives tips on how to stay young and lists so-called longevity recipes. They might disappoint meat lovers, but they don't sound completely hostile to pleasure either: couscous with fish, bread salad from Tuscany and pasta with aubergines. Longo also founded a company with products for fasting concepts, which he states in the appendix to the study.
In their work, Longo and Anderson emphasize that an anti-aging diet should be tailored to the individual. There is no one solution that is just as suitable for a fit 20-year-old as for a 60-year-old with a metabolic disease. Gender, age, lifestyle, health status and genes must be taken into account, they write. For example, people over 65 may need extra protein, they say.
For Kristina Norman, aging researcher at the German Institute of Human Nutrition, such adjustments are a very important point: "In old age, it is often difficult to take in enough protein. Too little of it can lead to muscle breakdown and, as a result, to an increased risk of falls and fractures. Then So eating a little more meat than is generally recommended can be advisable."
The author duo can look back on a wide range of work: starting with studies on yeast fungi, worms or flies through to clinical data and modelling. There are also findings on traditional nutrition in places where many people grow very old.
"A study in which a group is assigned Longo's recommended diet and end-up lifespan is compared to a control group would be very difficult to implement, so the authors approach this by pooling disparate evidence," Norman said. She considers Longo's and Anderson's theses to be convincingly documented.
There are many parallels to well-known recommendations, such as those of the German Society for Nutrition, and also to a menu that scientists proposed some time ago for a healthy and at the same time environmentally friendly diet. "Contrary to what is often assumed, recommendations for healthy eating do not change every few years. Overall, they are very stable," Norman said. "The Longo study can be seen as old hat, but the topic has been rethought and is increasingly supported by evidence."
For Bernhard Watzl, the former head of the Institute for Physiology and Biochemistry of Nutrition at the Max Rubner Institute, the review article shows above all that the quantity and quality of nutrition are crucial for a long life. "It's better to take in too little energy than too much." Regarding the underlying mechanisms in the body, he explains: "The more a system is required, the more it wears out." Rather, it is important to challenge the body at a low level.
When it comes to fasting, however, Watzl is less convinced of the data available to date than Longo: "Fasting is only for people who can't manage to limit their energy intake," he said. Then temporarily going without food could help to sensitize certain receptors in the body again.
In general, it is never too late for a healthy diet over the course of a lifetime, stresses Watzl. With some diseases that develop in the body over decades, the following applies: the earlier, the better. When asked, Longo replied that, according to a study, life expectancy could be increased by several years even in 60 or 80 year olds if many of the suggestions he had made were implemented. The study said the greatest benefits came from eating more legumes, whole grains and nuts, and less red and processed meat.
When it comes to the quality of the food, Watzl sees some habits in this country as positive: eating wholemeal bread or muesli, for example. "But it's easy to put too much cheese or sausage on the bread. Or you eat light bread." Watzl is also critical of heavily processed foods - because of the additives, but also because of the rapid availability of nutrients. That overwhelms the metabolism.
In general, Longo and Anderson recommend small changes in diet and discourage radical changes. Many are probably familiar with the problem of attempting a diet: If the plan is too restrictive, it cannot be sustained in the long term. The result is a yo-yo effect.
(This article was first published on Saturday, May 14, 2022.)