Nutrition for a long life and why diversity in the gut is healthy

The human gut is home to over 100 trillion microorganisms, the entirety of which is known as the microbiome. This unimaginably diverse and highly complex multitude performs numerous tasks for us. Our intestinal flora plays an important role in digestion and metabolism, but also in immune defense and even influences the hormone system. You can think of the microbiome as its own microcosm. The intestinal flora is even involved in the development of inflammatory processes. There is also close contact with other organs such as the liver and brain.

The composition of microorganisms is unique for each person. It is important that the composition of bacteria (diversity) is in balance. The multitude of tasks can only be managed by a healthy and stable microbiome. If pathogenic and harmful germs predominate, we speak of dysbiosis.

Dysbiosis a significant factor in the development of disease

However, such dysbiosis rarely occurs for no reason. If we do not offer good bacteria an optimal living environment, their number decreases and the number of harmful germs eventually predominates. We can influence this balance enormously with our lifestyle: Diet, exercise, medication intake and environmental influences all have an effect on our personal microbiome. Many studies have now shown that an unbalanced gut microbiome plays an important role in chronic diseases, including inflammatory bowel disease, obesity, type 2 diabetes, cardiovascular disease and cancer.

In 2017, a study at Lund University found that dysbiotic gut flora accelerates the progression of Alzheimer’s disease. A gut-friendly diet with plenty of whole grains, fruit and vegetables can therefore help prevent Alzheimer’s.

Positive effects of a change in diet visible after just 24 hours
It is undisputed that diet shapes the composition and diversity of the microbiome, and does so exceptionally quickly. A change in diet – for example from a diet rich in animal products to a predominantly plant-based diet – causes a remarkable microbial shift within 24 hours.

The links between the gut microbiome, diet and systemic inflammation indicate that a high-fiber diet favorably models the composition of the microbiome. Fiber increases the number of beneficial bacteria, inhibits the growth of pathogenic germs and reduces dangerous serum cholesterol in the microbiome. They also promote the production of important short-chain fatty acids.

In countries where a high-fiber and low-fat diet is preferred, the population also achieves the highest life expectancy.

The microbiome in balance enables healthy ageing

The microbiome undergoes major changes with increasing age. It develops during the first three years of life and then remains relatively stable until middle adulthood. However, the ageing process generally appears to be favorably influenced by the balance of various immunological processes. The gut microbiome can support or even increase anti-inflammatory activities, thus balancing the increased pro-inflammatory activities that occur in all older adults. The balance of the microbiome is crucial for healthy ageing. Healthy older people have a stable and diverse gut flora well into old age.

Short-chain fatty acids, SCFAs, appear to be key compounds. They are produced by bacterial fermentation of dietary fiber in the large intestine and influence many processes in the body. For example, they can trigger processes that stop the growth of tumor cells and promote apoptosis, i.e. the programmed death of harmful cells. SCFAs also have a positive influence on insulin sensitivity and are important for a smooth fat metabolism.

It was found that younger subjects have more SCFAs than older subjects. It is assumed that impaired health in old age is associated with reduced SCFA levels.

Healthy into old age with the right diet: longevity is also a question of nutrition

Cream cakes, pork schnitzel, burgers and the like – there are people who prefer to eat only these or similar foods. They can hardly hope to grow old in good health. On the other hand, the right diet offers us a good chance of staying healthy and extending our lifespan. This is because there is good scientific evidence that healthy eating habits significantly increase the chances of longevity.

For a long time, it was assumed that our life expectancy was primarily determined by our genes. Researchers have disproved this. Using model calculations, they have determined that the importance of genes with regard to our lifespan is significantly overestimated: The share of genes in our life expectancy is probably only around 10 percent. Around 90 percent of the factors that determine our lifespan are therefore apparently due to our lifestyle. Sufficient physical activity and a healthy diet that promotes longevity are important.

What this means in concrete terms can be learned from populations living in regions of the world with an unusually high number of very old people. These include, for example, Abkhazia on the Black Sea, the mountain village of Vilcabamba in Ecuador, individual areas on the Mediterranean island of Sardinia and, in particular, Okinawa in Japan, where longevity is almost normal and the number of very old people is at its highest.

There are certain things that these longevity societies have in common, such as regular, moderate physical exercise, a diet based more on plant-based products and low in meat, and adherence to traditions.

Sweet potatoes instead of pork schnitzel

Diet seems to be the linchpin here. The inhabitants of Okinawa in Japan show what it should look like to grow old healthily: they eat mainly root vegetables, especially sweet potatoes, green and yellow vegetables and soybean-based foods. They consume moderate amounts of seafood, lean meat, fruit, herbs, tea and alcohol. Following the dietary principles of Okinawans reduces oxidative stress, is likely to modulate age-associated biological pathways, reduces the risk of developing chronic age-associated diseases and thus promotes healthy ageing and longevity.

The principles of such a diet can also be found at the heart of the Mediterranean diet, which is considered particularly healthy in this country. This is because it appears to prevent cardiovascular disease and age-related illnesses in general. The Mediterranean diet is based on a high proportion of unrefined carbohydrates in the diet, only moderate consumption of protein with predominant consumption of vegetable proteins as well as fish and lean meat. It is also important that the diet contains a low proportion of fat, with unsaturated fatty acids predominating. However, the diet should be rich in omega-3 fatty acids. Such a diet is said to have anti-inflammatory effects, optimize the cholesterol balance and also have a positive influence on other risk factors for age-related diseases.

Low glycemic load

The emphasis on a plant-based diet also results in a comparatively low calorie density, meaning that fewer calories are generally consumed. This type of diet also has a low glycemic index (GI) and a low glycemic load (GL), which is generally considered to be particularly healthy. This is because the GI and therefore also the GL of the food are a measure of how a carbohydrate-containing food affects the blood sugar level. The lower the GI, the less and slower the blood sugar level rises.

The glycaemic load, on the other hand, is an indicator of the insulin requirement triggered by the diet. Foods with a high GI, such as white flour products, sweets or sweet drinks, cause a rapid rise in blood sugar. This is accompanied by an increase in insulin levels in the blood, whereby insulin has the task of promoting the absorption of sugar into the body cells as well as the build-up and deposition of fat and making it more difficult to break down fat – effects that are not beneficial to our health.

Starving instead of feasting

Apparently, our diet and our genes can also influence each other with regard to ageing. The gene “forkhead box protein O3”, FOXO3 for short, appears to play a central role in ageing processes. This is probably diet-dependent, with starvation appearing to be more favorable for the ageing process and feasting more unfavorable, as scientists from the Cluster of Excellence “Inflammation Research” at Kiel University have discovered.

According to the researchers, the first indications that the FOXO3 gene has an effect on age date back to 1993, when it was observed that the lifespan of nematodes doubles when FOXO3 is activated. Subsequently, this gene was also examined more closely in humans and it became clear that FOXO3 can promote longevity. Studies on very old people indicate that increased expression of the FOXO3 gene promotes a long lifespan, an effect that has also been observed in worms, flies and mice.

However, the life-prolonging effect of the gene apparently only comes into play if the diet is not high in calories, i.e. if the person in question is starving rather than consuming too much food. This appears to be due to evolution. Studies on human skeletons from the Neolithic period show that the longevity variant of the FOXO3 gene was more common in the population at that time than it is today. This may have been a survival advantage for people at that time, who inevitably often had to go hungry.

When our ancestors then became sedentary and ate more carbohydrates, animal protein and also fats, the longevity variants could have become rarer, the Kiel scientists assume.

Does hunger make us live longer?

Experiments on flatworms also suggest that starvation can have a positive effect on healthy ageing: The animals have an unusually high regenerative capacity and can even regrow individual body parts. They also have special survival strategies during periods of food shortage. The animals then shrink and only grow again when sufficient food is available. This is regulated by the length of the so-called telomeres. These are a kind of protective cap at the ends of the chromosomes. They become shorter with each cell division, which is interpreted as an ageing process. In a state of starvation, the stem cell pool from which the organism regenerates is modulated in such a way that cells with long telomeres predominate. From the researchers’ point of view, this indicates a rejuvenating influence of starvation phases on the cells.

Slow dietary changes instead of a radical diet

The effect of a healthy diet is likely to be greatest if the principle is taken to heart throughout life and from an early age. However, studies show that a change in diet in midlife is also effective. More whole grains, fruit, vegetables, fish and nuts is the motto that can clearly reduce the risk of death. In particular, deaths due to cardiovascular diseases are less common with such a diet and mortality from cancer is also lower.

This does not mean that a radical diet is necessary. According to studies, it is sufficient to eat an additional portion of nuts or pulses every day and to avoid a portion of sausage or red meat. Moreover, it is not a question of eating or not eating a particular food, but of improving your diet in general.

Sources:

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