Food with umami can often be prepared with significantly less salt, sugar, and fat without sacrificing the delicious taste of the resulting dish. Salt, in particular, is frequently applied too liberally in order to compensate for ingredients that are insipid or unpalatable. In many cases, its use can be reduced by as much as a half by incorporating foodstuffs with umami into the recipe. The fifth taste spurs the appetite, an attribute that can be exploited to advantage in caring for the sick and the elderly, who may have lost interest in eating. At the same time, however, umami promotes satiety, which helps to curb overeating by those who are inclined to overindulge. Either way, adopting a diet that has an abundance of umami may be a way for modern humans to eat in a healthier manner and to adjust their caloric intake to suit the needs of their bodies.
On virtually any given day of the week, one can see advertisements in newspapers and magazines for products—usually prepared foods, cosmetics, and textiles—that purport to be free of ‘chemicals.’ Whether we like it or not, however, at a fundamental level all material substances are made up of chemicals. So the advertising slogans are complete nonsense and shift the focus away from the more central questions of whether the items are wholesome, nutritious, safe to use, and sustainable. To a certain extent, the effectiveness of such advertising depends on ignorance or scientific illiteracy and, in the worst-case scenario, on a willful denial of established facts. The clear implication is that chemistry and chemicals pose a danger to humans; the subtext is that those products that are derived as directly from nature as possible are better for us.
Unfortunately, this is a distortion of reality. For example, a very significant proportion of natural ingredients sourced from plants and fungi are, to varying degrees, poisonous. There is nothing strange about this. Many living organisms either contain certain chemicals in their bodies or are able to secrete them as part of their survival strategy to protect themselves from predators. In contrast, many synthetic products are harmless and safe, precisely because they are made under well-controlled conditions from chemically pure ingredients that are known to be harmless.
For a certain segment of the population, food without chemicals basically means food without additives. But this raises two important questions: What constitutes an additive, and to what extent should it be considered natural? By definition, table salt (NaCl) is regarded as a food, regardless of how it has been produced, and therefore it does not have to be declared as an additive. The same holds true for other household staples, like vinegar. This is a matter of history and tradition. In contrast, monosodium glutamate (MSG), regardless of how it was produced, whether naturally or synthetically, is defined as a food additive by the governments of some countries and must be identified as such. In the United States, MSG is declared GRAS (generally recognized as safe), but foods containing added MSG must list it on the ingredient panel on the packaging. In Australia, New Zealand, and the European Union, MSG has to be listed as a food additive.
As shown in the tables at the back of the book, many so-called natural foodstuffs contain a large amount of MSG, either when raw or as a result of cooking, fermenting, drying, or aging. It is therefore misleading to talk about foods to which MSG has been added as foods with chemicals.
It is also important to keep in mind that too much MSG has the effect of making food less palatable. In a sense, then, it is considered a self-limiting substance, and there is a general tendency on the part of food processors to use the least amount necessary to maximize taste.
Generally speaking, regulatory authorities have not issued rulings on the subject of safe daily limits for the intake of MSG, as no one has been able to determine exactly what such a limit might be. Some researchers have cautiously suggested that it could be set at 2.1 grams per kilogram of body weight. This quantity is so relatively large that it is highly unlikely that anyone would ingest even a tiny fraction of this amount.
Regrettably, even though MSG is the most intensely researched substance found in foods, it is virtually impossible, even in a well-informed society, to dislodge what amounts to a superstition; namely, that food with MSG is food that is laced with dangerous chemicals.
Umami can help to regulate appetite. When one has ingested enough umami substances, the desire to eat more attenuates and food intake is limited to a level that matches the body’s nutritional needs. At the same time, signals are sent from the receptors on the tongue to the stomach and the pancreas to forewarn them that protein-rich food is on its way. In this way, the presence of umami promotes better digestion of the proteins. The effect of the ingestion of umami on appetite and digestion illustrates a general phenomenon called homeostasis. Homeostasis describes a balance in which opposing tendencies interact to produce a form of self-regulation that maintains an equilibrium. Food with umami can, therefore, serve as a good weapon in the global fight against obesity.
Recent research may be well on the way to finding a physiological explanation for why umami can act as an appetite regulator. The stomach and intestines have a well-developed nervous system, which, to a certain extent, functions autonomously and independently from taste perception, but which is also linked to the brain via a certain cranial nerve, the vagus nerve. One can think of this network of nerves in the stomach as a sort of mini-brain that is responsible for peristalsis in the intestines, digestion, and part of the immune system. This ‘stomach brain’ in humans has just as many nerve cells as a cat brain and just as many different types of nerve cells as the human brain. It is this ‘stomach brain’ that discerns when we have had enough to eat. But sometimes will power causes the actual brain to take control and ignore the signal, and we continue to eat.
A glutamate receptor that has been found in the stomach of research animals resembles the one found in the taste buds on the tongue. Experiments showed that an increase in glutamate in the stomach, by binding to this receptor, stimulates the vagus nerve, which in turn sends a signal to the brain that the fundic glands in the stomach sac need to secrete more of certain enzymes (proteases), which break down proteins. In this way the glutamate may act as a trigger that sets in motion the chain of events alerting the stomach to prepare for the imminent arrival of protein-rich foods that need to be digested. Perhaps in the course of evolution this effect has been partly responsible for the extent to which we like the taste of glutamate. Apparently, other amino acids are not able to activate this signal.
A long stay in the hospital or certain debilitating medical treatments can leave seriously ill people in a very weakened state. Even the act of eating can pose problems for them if they lack physical strength to do so or if they have lost their appetite. By turning our attention to how to optimize umami in the food, we could design small, nutritious portions that have more appeal. One way would be to reduce drastically the amount of cooking liquid to result in a more concentrated taste.
In many parts of the world, the population is aging. Even though these older people may remain active and healthy into advanced age, they will inevitably suffer from illnesses and aches and pains that reduce the quality of life. In addition, the senses become less acute, particularly over the age of seventy. It is not just eyesight that is affected but also the ability to taste and smell. This can lead to loss of appetite because the food seems to be less appealing and is judged to be less tasty, with the result that older people may eat too little or seek out the wrong foods. The consequences are malnutrition or insufficient caloric intake, a weakened immune system, and greater risk of illness. An associated problem is that bland food does not stimulate the secretion of sufficient saliva, which leads to poorer digestion and an attendant diminished uptake of nourishing substances. These difficulties affect not only the old who are living on their own but also those who are in nursing homes or hospitalized.
Experiments have demonstrated that many of these problems can be alleviated by augmenting the umami content of the food, either by adding MSG directly or simply by preparing it with ingredients that are able, from the outset, to impart more savoriness. Tests have also shown that umami has a much greater ability than sourness to stimulate secretion of saliva during an ensuing period of two to ten minutes. More saliva increases the capacity to dissolve more taste substances, which intensifies their taste, and it becomes easier to chew and swallow the food. As a consequence, the elderly are more willing to eat, leading to improvement in their nutritional state and boosting their resistance to disease.
Another important consideration is that adding umami allows for a reduction in the salt content, which is good news for those among the elderly who suffer from high blood pressure. There are already moves to limit the amount of salt in institutional food, but this leads to many complaints about how it tastes. By placing greater emphasis on how to add more umami to the food, it is possible to get by with less salt without sacrificing palatability.
There are very few places where umami has been introduced systematically as a means of improving institutional food. Even in Japan, where umami was first given a name, investigations have shown that the salt content of the food for elderly patients in nursing homes is regulated within a relatively narrow range (361–1,516 mg/100 g), whereas the glutamate content varies somewhat arbitrarily (16–697 mg/100 g). Seemingly, even in Japan, umami has not yet been adopted as a central parameter for the preparation of food for older patients.
It would certainly appear that there is a vast, unexploited potential for making informed use of the fifth taste in many of the kitchens where food is prepared for the sick and the old.
From the day we are born until the day we die, our lives as Homo sapiens are inseparably bound up with our relationship to food and its taste. Our health and survival are dependent on having a balance of different and sufficient nutrients. The quality of our lives is tied to the palatability of the food and the harmonious taste impressions we experience.
From prehistoric times, our species has had an instinct to seek out food that has a high energy content and is nutritious. In a healthy person, this instinct is underpinned by self-regulating mechanisms that help to control our weight and determine our overall physical well-being. In this context, an understanding of umami becomes a central concept for enhancing wellness and enjoyment of life, from start to finish.
It behooves us to become better at acknowledging the meaning of umami at every stage of our lives. There is a reason why it is found in mother’s milk; there is a reason why, throughout our lives, we collect fond memories of delicious meals; and there is a good reason why we need to make sure that the sick and elderly among us have access to food that tastes better and has more umami.
◀ Sun-ripened tomatoes are rich in glutamate and adenylate and hence contribute perfect umami synergy.
