The Power Of Youth. How To Tune Our Mind And Body For A Long And Healthy Life

METABOLIC RATE AND LIFE EXPECTANCY

"Vital energy is like motor fuel, the faster the car goes, the faster the gas runs out" – this point of view is shared by supporters of the theories connecting the rate of metabolic processes and life expectancy. The origins of this position are in studies of the German physiologist Max Rubner, who in the early XX century proposed the rate of living theory. Rubner noted that the larger an animal and the longer it lives, the less energy it consumes per gram of body weight. Roland Prinzinger, a follower, and compatriot of Max Rubner, believes that all living creatures use around 2.5 million kJ per gram of body weight during their lifetime. According to Prinzinger, this is the "fuel volume" limiting our life.

In the early 21st century, German doctors Peter Axt and Michaela Axt-Gadermann wrote a popular science book called "The Joy of Laziness: Why Life Is Better Slower – and How to Get There". The authors claim that excessively active people (especially professional athletes) have a shorter life span, and suffer from heart and vascular diseases and cancer more often than those who do not show excessive activity.

At the same time, over the years with the advent of the rate of living theory, there have been many studies that refute Max Rubner's position, which linked the body size of an animal, its metabolic rate, and life expectancy. For example, a hummingbird is the smallest and most "metabolically active" of all birds: its heart rate in flight exceeds 1200 beats per minute, and its respiratory rate is 250. At such metabolic rates, a hummingbird's life span should be very short – no more than a year.

However, its average lifespan is about five years. It is comparable to the lifespan of most species of wild pigeons, having a much more "resting" metabolism and living 5–7 years. Moreover, there are some long-living hummingbirds, whose age makes 10–12 years.

One explanation that allows us to understand why such a huge energy consumption does not affect the lifespan of the hummingbird is related to daily fluctuations in the metabolic rates of this bird. During the night, the hummingbird's body temperature drops below 20 ℃ and the pulse rate drops to 50–100 bpm. The high-speed daytime metabolism is replaced by a nighttime anabiosis, similar to a short winter sleep.

The hummingbird example shows that Rubner and his followers' approach is too "mechanistic." Many factors affect the body's work, including metabolic processes, which are highly variable and adaptable to different conditions. At the same time, there is some common sense in longevity theory and similar hypotheses: during the last few decades, much research has been conducted to study the effect of various factors on metabolism (and longevity). These include caloric deficiency, hypoxia (oxygen deficiency), and heat deficiency.

HOW DOES CALORIE RESTRICTION AFFECT METABOLISM AND LIFE EXPECTANCY?

Scientists believe that one of the secrets to the longevity of Okinawans is a reduced-calorie diet. Inhabitants of this blue-zone region have incredible longevity, with many crossing the 100-year threshold. In addition, Okinawans are much less likely than other Japanese to die from cardiovascular disease (59 %) and cancer (69 %)^[103]. By analyzing the diet of Okinawans, scientists concluded that school students in the region consume 38 % fewer calories than their peers in other regions of Japan, and the caloric content of the daily food diet of adult Okinawans is on average 20 % lower than that of other inhabitants of the Land of the Rising Sun.

Yet, the link between the low-calorie diet of Okinawans and their high life expectancy (as well as their excellent health in adulthood) is still only a hypothesis. Scientists continue to actively investigate it, conducting various experiments involving animals and humans.

Experts from Texas University studied the metabolism of a group of mice whose calorie intake was 40 % lower than that of animals in the control group from the age of 6 months until the end of their lives^[104]. These rodents showed a decrease in metabolic rate at 6–12 months of age. However, when the mice reached 18 months of age, their metabolism activity became the same as that of animals on a standard calorie intake.

Scientists concluded that a calorie deficit leads to a gradual shift in metabolism and the activation of adaptive mechanisms that normalize the rate of metabolic processes. According to experts, it is the mobilization of compensatory systems similar to those activated during mild stress that may underlie the increase in lifespan with a low-calorie diet.

Meta-analysis of studies on the connection between metabolic rates, caloric deficit, and longevity of animals showed that there is no direct and obvious relationship between these factors^[105]. As it turned out, there are many factors affecting the relationship between metabolic activity and longevity of animals, including housing conditions and individual experience.

The most significant experiment to study the effects of caloric restriction on metabolic processes in humans was conducted in 2018 as part of the Calerie (Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy) project^[106]. The experiment involved over 50 volunteers who reduced their caloric intake by 25 %; the subjects adhered to this restriction for two years. During the whole experiment, the subjects lost an average of 9.4 kilograms, and the main weight loss was due to a decrease in body fat. After a period of active weight loss, there was a period of stabilization (maintenance of the achieved results).

During the period of active weight loss, a 10 % slowdown of basal metabolism (energy expenditure during sleep) was observed in the subjects. A study of the hormonal profile of the subjects showed that the level of leptin decreased in the blood of the volunteers, indicating a slower metabolism. Also, during the period of active weight loss, there was an increase in adiponectin, a hormone synthesized by fat cells (its level decreases in obesity). Adiponectin is a regulator of metabolic processes, and its increase indicates a tendency to normalization of metabolism. During the period of weight stabilization, there was a decrease in thyroid hormones in the volunteers, which indicated a slowdown in the rate of metabolic processes in the body. A low concentration of these hormones is recognized as one of the biomarkers of aging.

The experiment showed that changes occurring against a background of prolonged caloric deficiency in the human body cannot be interpreted as unambiguously positive. On the one hand, in active weight loss, there are positive transformations, associated with a decrease in leptin and adiponectin. On the other hand, during prolonged caloric restriction, there are also bad shifts, which include a decrease in thyroid hormone levels.

LOWERING BODY TEMPERATURE AND AN INCREASE IN LIFE EXPECTANCY

Man is a warm-blooded animal. The ability to regulate body temperature makes it possible to live in regions with different climates and to maintain a high level of activity year-round. But this evolutionary bonus is paid for, for example, by huge energy expenditures, due to which warm-blooded animals consume dozens of times more food than cold-blooded creatures of the same weight, as well as, quite probably, the ability to live long.

Almost all animals with the ability to slow down metabolism, including temporary "cooling" during hibernation (or torpor), live longer than evolutionarily related species that maintain a high body temperature. For example, mice that are awake year-round rarely live beyond four years, while the lifespan of gophers, representatives of the same order that go into hibernation, is about seven years.

According to biologists, the ability to lower body temperature by 2–3 degrees helps increase lifespan by 1.5–2 times.

The only mammal known to science whose body temperature depends on its environment is the naked mole rat. This creature living in savannas and semideserts of some African regions is a close relative of mice and rats but lives ten times longer than its closest relatives: about 30 years against 1.5–3 years typical for ordinary rodents.

Naked mole rats live in colonies in underground tunnels: when it gets cooler, they move closer to the surface and gather in groups, minimizing heat loss. The animals are resistant to oxygen deficiency and high concentrations of carbon dioxide, which are fatal for other rodents. Researchers believe that the reason for this persistence is the slow metabolism, which is half as fast as that of similar individuals. The low body temperature, along with some other features of mole rats (for example, the ability to get "stuck" in childhood for their whole life), scientists believe to be the key factor in their unprecedented lifespan for rodents.

FUN FACT

CAN A PERSON GO INTO HIBERNATION?

Getting a person into the so-called hibernation state – a process in which the metabolic rate, namely heart rate, respiration, body temperature, oxygen level, etc., is reduced – is a plot for a science fiction movie, because only some animals can hibernate, but not humans. However, studies have shown that artificial activation of certain neurons allows mice to go into a state similar to hibernation – torpor – even though it is not natural for them. And if it was possible for them, it may be possible for humans as well. The uses of the method range from treating a multitude of diseases to space travel.

Is it possible to artificially lower body temperature to increase life expectancy? Experts from Scripps Research in California (USA) found that the health effect of low-calorie diets is related to metabolic processes that cause a decrease in body temperature^[107]. They took two groups of mice, which were placed in cells with different temperatures: the first was 22 ℃ (normal room temperature), the second – 30 ℃ (at this temperature the body of mice is in heat balance with the environment, and the mechanisms of body thermoregulation are inactive).

Then they were divided into subgroups: some of them gradually reduced the amount of food per day, and others ate as usual. During the experiment, scientists monitored the changes in metabolites in the blood and brain of the animals, depending on their diet or body temperature. The study found that under conditions of caloric restriction, the temperature had the same or even greater effect on metabolism than the amount of nutrients.

The analysis identified specific metabolites responsible for changes in body temperature. For example, the hypothalamus of mice living at room temperature produced large amounts of nitric oxide molecules and the neuropeptide leucine-enkephalin. Scientists separately injected these metabolites into mice and found that the health effect of caloric restriction increased.

OXYGEN DEFICIENCY, METABOLISM, AND LONGEVITY

One of the secrets of the naked mole rats' long life, scientists believe, living in hypoxia – oxygen deficiency. At present, scientists conduct research to study the effect of artificially created hypoxic conditions on health and longevity. The most spectacular experiment in this direction was conducted on animals. Scientists from the National Academy of Medical Sciences of Ukraine and the Ben-Gurion University of the Negev, using artificial hypoxia, managed to turn ordinary mice into their long-lived brethren – naked mole rats^[108].

Experts have simulated the living conditions of naked mole rats in cages for mice: to do this, they have reduced the oxygen content from 20 to 10 % and increased the concentration of carbon dioxide from a small fraction of the % to up to 10 %. Next, the experts made three groups of mice live in these stuffy conditions: young, adult, and elderly – for three months. It turned out that during this time the number of respirations was halved in rodents of all groups, and body temperature dropped by several degrees and then stabilized at this level.

The animals began to eat 40–50 % less than usual (although they had plenty of food) and lost 25–30 % weight. In addition, the scientists recorded that the rodents were not stressed – this was shown by experiments at the intracellular level. In terms of behavior, the animals also showed no changes: their activity and sleep remained at the same level. Specialists noted that the wounds on the mice healed faster than under normal conditions. That is, under the heat, the laboratory mice became like naked mole rats.

According to scientists, the body's adaptation to low oxygen levels is one of the reasons for the longevity of mountain dwellers. Scientists from the University of New Mexico (USA) and Fudan University (China) found out that the representatives of the Mosuo people, who live in high-mountain areas of the Himalayas, suffer from hypertension much less often than the inhabitants of plains and foothills^[109]. Moreover, they practically do not develop anemia, which is characteristic of diabetes (although cases of diabetes are registered). Experts found that highlanders do not suffer from oxygen hunger even in situations when the oxygen concentration in the air significantly decreases: in response to this, the blood vessels of highlanders can expand as much as possible. This way the body prevents the development of hypoxia.

CONCLUSION: SHOULD WE CONSCIOUSLY AFFECT THE METABOLIC RATE?

Research shows that our metabolism is a very complex system with multilevel regulation. Therefore, it is hard to affect it with simple methods (e.g., moving more and eating less). Thousands of years of evolutionary development have taught our metabolic mechanisms to hold their own when faced with factors such as hunger or excessive activity because the body perceives them as a threat to survival. At the same time, measures that are usually recommended to speed up the metabolism, especially physical activity, have a powerful positive effect on the body, protecting it from the development of a wide range of diseases.

Following calorie deficit dietary recommendations also leads to positive changes. Restricting energy intake from food helps control weight and acts as a "soft" stressor, activating the body's adaptation mechanisms to increase longevity. Our task is not so much to find levers to speed up or slow down the metabolism, but to find the optimal balance between energy storage and expenditure, between the state of tension and relaxation, and between excessive and "useful" stress. A lifestyle of sufficient physical activity, a rational diet, practices that allow us to cope with excessive stress and healthy sleep will create the conditions for maintaining the rate of metabolic processes that is necessary to stay healthy for many years.

CHAPTER 10
NUTRITION

HUMAN HEALTH DEPENDS NOT ONLY ON GENETIC FACTORS BUT IS LARGELY DETERMINED BY HABITS, LIFESTYLE, AND ECOLOGY. NUTRITION PLAYS THE MOST IMPORTANT ROLE IN MAINTAINING A HEALTHY BODY: IT IS ABOUT THE AMOUNT OF FOOD CONSUMED, ITS QUALITY, AND THE RATIO OF DIFFERENT COMPONENTS IN THE DIET.

Many diseases that have become widespread around the world in recent decades are related to imbalances in nutrition. Therefore, everyone needs to know the basic principles of a healthy diet, as well as consider the individual characteristics and needs of the body.

INTRODUCTION TO NUTRITIOLOGY

The diet of many modern people is quite monotonous and includes many high-calorie dishes, fats, and simple carbohydrates, provoking the development of metabolic disorders and obesity. At the same time, the modern style of the diet of people in developed countries is characterized by a low content of foods rich in fiber and vitamins, healthy fats, and high-quality proteins.

For this reason, the number of people suffering from the consequences of poor nutrition is increasing day by day. First, we are talking about a global obesity epidemic. According to statistics from the World Health Organization, at least 2.8 million people die annually from diseases associated with excess weight, and experts from the Endocrine Society of the USA report that obesity is the cause of death of over 4 million people a year. At the same time, the number of people suffering from overweight is increasing every day. Among other diseases caused by irrational nutrition – are atherosclerosis, coronary heart disease, diabetes, osteoporosis, hypertension, and many other pathologies.

There is a whole science that studies how the different components in food interact with each other and the body. It is called nutritiously: the name comes from the Latin word nutritio – "nutrition," and the Greek word λόγος – "study." Nutrition experts are interested in the nuances of people's eating behavior, such as the motivations that guide people's food choices, the development of both global healthy eating strategies, and individual dietary recommendations.

The main task of nutrition is to provide the body with nutrients. They serve as sources of energy and act as a building material for the creation of cells and intracellular structures, hormones, enzymes, and other biologically active molecules, for tissue renewal. Protein, fat, and carbohydrate molecules in food are macronutrients and are the basic building and energy substrates.

Unlike macronutrients, which shall be consumed normally each day, micronutrients are only needed in very small amounts. Micronutrients include vitamins and minerals. For example, they are used to regulate metabolic processes, affect the speed of biochemical reactions, and some are part of larger molecules. A deficiency of proteins, fats, and carbohydrates quickly leads to tangible consequences: a person suffers from a lack of energy, metabolic disorders, and general exhaustion. It takes time to feel the effects of micronutrient deficiencies, but the negative consequences are inevitable.

The important role that food plays in health and disease has been evident since ancient times: even Hippocrates mentioned in his manuscripts the connection between gout (a metabolic disease that affects joints and kidneys) and an excess of meat products in the diet. However, the position in which one or another macro or micronutrient is declared an enemy or panacea for all health problems is fundamentally wrong.

In the 1970s, scientists discovered that cholesterol plays an important role in the development of cardiovascular disease. This discovery led to a veritable "fat-free boom," as over the next two decades people began to cut back on fat in their meals, and fat-free foods filled stores. But further research showed that vegetable fats, as well as fatty fish, on the contrary, protect against atherosclerosis and heart disease.

The discovery of the effect of vitamins in maintaining health was the reason for their enormous popularity. However, there is still no evidence that synthetic vitamins can make a significant contribution to disease prevention. On the contrary, studies show that vitamin addiction can lead to health problems.

Today, the key criteria for a healthy diet are balanced (the presence of all micro and macronutrients in sufficient but not excessive amounts) and a personalized approach to dietary planning.

WHAT DOES GUT HEALTH DEPEND ON?

For many years, the functioning of the human digestive system was perceived from a mechanistic point of view. Digestion was seen as a step-by-step grinding of food – mechanically (in the oral cavity) and then chemically by enzymes. As a result, eaten food turns into the smallest structural components, which enter the blood and lymph through the intestinal wall, and the undigested remains are excreted with feces.

Today, however, it is becoming apparent that digestion is a complex process with multilevel regulation. It was found that there is a close connection between the brain and the digestive tract. The intestines are "equipped" with their nervous system (enteric nervous system, ENS), which can function independently of the central nervous system. The ENS consists of a huge number of nerve cells and is regulated by the same neurotransmitters that are needed for brain functioning, such as serotonin and dopamine.

The brain and gut are constantly exchanging signals (the "gut-brain" axis). It is not surprising that the digestive tract is sensitive to stress and mood swings, and, on the contrary, eating a certain food allows it to affect our emotional state, to calm down or, to cheer up.

The digestive tract is filled with a huge number of microorganisms (there are 100,000 times more of them than people on Earth). Collectively, they are called the intestinal microbiota. Its representatives – bacteria, archaea, Proteus, fungi, and viruses – help to digest food, regulate metabolism, neutralize dangerous substances, and strengthen the immune system.

Microbiota composition is largely determined by nutrition style. In one study, Italian researchers from the University of Florence compared the microbiota of children living in rural settings in Burkina Faso, West Africa, with the microbiota of children living in urban settings in Florence^[110]. The former ate mostly natural foods: their diet included cereals, vegetables, and sometimes chicken. The latter ate mostly pasta, pizza, chips, breakfast cereals, and soda. It turned out that the microbiota of children from Burkina Faso was richer and more diverse, and the level of beneficial bacteria was higher than that of the children from Florence. Poor and "unhealthy" intestinal microbiome of Western children formed from such a diet, according to many scientists, is a health hazard because it provokes allergic reactions, obesity, type 2 diabetes, autoimmune diseases, mental disorders, and many other diseases.

Low-carbohydrate, raw food diets, and other dietary fashion advocates often call for giving up certain foods in favor of others, eating less, and exercising a lot to reduce excess body weight. But the human digestive system is much more complex. Intestinal microorganisms determine exactly how appetite will be regulated, energy will be expended, how many calories will be deposited as fat, and how much inflammation will occur in cells. The intestinal microbial landscape is unique to each person, and its composition determines the individual characteristics of the assimilation of certain foods, and metabolic and mental processes.