As global incomes rise, traditional diets are being replaced by those high in animal products and refined sugars, fats, and alcohol. This dietary shift, along with urbanization and reduced physical activity, contributes to the increasing prevalence of obesity and lifestyle-related diseases. The challenge lies in promoting healthier and more sustainable diets. Recognizing individual needs based on age, metabolism, and genetics adds complexity to nutritional considerations. Taste is a crucial factor in promoting low-energy, low-salt, yet nutritious diets. The Japanese traditional diet, known as Washoku, emphasizes fish, soybean products, and minimal animal fat and meat, utilizing umami taste to enhance palatability. This dietary pattern may be linked to the longevity observed in the Japanese population.
Understanding Umami and Its Role
Umami, the fifth basic taste often described as "savory," is primarily elicited by the free amino acid glutamate. Monosodium glutamate (MSG) is the commercially prepared sodium salt of glutamate. This savory taste is a hallmark of many traditional Japanese foods. Several receptor mechanisms are believed to be responsible for detecting glutamate on the tongue and palate.
Ikeda, who identified glutamate as the primary umami taste compound, suggested it helps identify protein sources. Some researchers propose that protein status influences sensitivity to umami. Early studies showed that both well-nourished and malnourished infants preferred soup seasoned with MSG. However, recent research suggests that the preference for umami may be influenced by protein consumption levels. Further research is needed to fully understand the relationship between umami sensation, preference, and nutritional needs.
Food technologists have identified foods naturally rich in umami substances, such as soup stocks, mushrooms, tomatoes, and fermented cheeses, thanks to extensive analysis of glutamate and 5′-ribonucleotides (inosine monophosphate (IMP) and guanosine monophosphate (GMP)) in food ingredients. IMP and GMP synergize with glutamate to enhance umami taste. However, the characteristics of umami taste in complex food systems require further study. Therefore, we will focus on the evidence that explains the unique role that umami plays in the Japanese traditional diet, known as Washoku. We also discuss its potential application in other diets.
Japanese soup stock, dashi, contains significant amounts of glutamate and IMP or GMP, depending on the type of dashi. It is believed that the particular profile of umami substances in dashi enhances the original flavors of foods and increases their palatability. The effect of umami substances is described as “meaty and mouthful”, “coating sensation” or even tactile. The exact mechanism by which glutamate and 5′-ribonucleotides function to create this effect cannot be fully explained by the activation of glutamate receptors on the tongue. Glutamate plays an important role in the palatability of foods, and its palatability is not entirely due to learning. Early behavioral studies based on the analysis of facial expressions in neonates showed that the addition of 0.5% MSG was able to reverse the typical aversive response of spitting and gaping to a clear vegetable soup. In fact, newborn infants displayed a similar response to soup with added MSG as they do to sweet solutions: sucking and positive facial expressions. This reaction of acceptance of MSG in soups by newborns is representative of the effect of glutamate in other foods in adults as well as children. Strangely, in an aqueous solution, MSG is unpalatable to both adults and infants. The reason for this is obscure. The optimal concentration of MSG, which usually ranges from 0.04% to 1.6%, has the ability to increase the acceptability of foods by changing the sensory and consequently, hedonic or pleasant properties of food. Added glutamate also increases the liking of novel flavors, in much the same way that fat and sugar do. Sugar and fat are thought to influence liking via their caloric content and reward effect. It is not clear in the case of MSG how umami influences liking. The increase in palatability by MSG is so robust that it can maintain the acceptability of food with reduced salt, which also works by improving the perception and flavor intensity in food. That is, studies have confirmed that the partial substitution of salt by MSG allows for an overall decrease in sodium without reducing food palatability. Thus, added MSG could be an effective strategy to decrease sodium concentration in foods. Prescott and Young illustrated how MSG increases the acceptability of soups, even among consumers that have a negative outlook towards MSG. Consumers rated the flavor of foods with added MSG as significantly better liked, richer, saltier, and more natural tasting. This higher food acceptability after adding MSG also influences food choices and, consequently, food intake. This property has been used to improve the nutritional status of older individuals. Altogether, substantial research indicates that MSG and natural glutamates from dashi or other foods rich in umami could play a role in enhancing the palatability and promoting the consumption of nutritious foods with low sodium content. It thus has the potential to be strategically used to decrease the intake of animal-based ingredients and enhance intake of others that promote overall health, such as vegetables, as is done in Washoku. There is a long history for the use of MSG as a flavor enhancer, which the Food and Drug Administration of the United States has categorize as generally recognized as safe (GRAS).
Read also: The Hoxsey Diet
The Science Behind Umami's Palatability
The reason for umami's effect on palatability is still unclear, but several explanations exist. The sodium content of MSG may play a role, but studies have shown that subjects prefer soup with MSG even when sodium levels are the same. Umami's interaction with other taste modalities is another possibility. This interaction can affect taste intensity or the temporal evolution of a taste sensation.
Umami sensation can enhance the perception of saltiness and make sourness more pleasant. There is also evidence suggesting that glutamate can augment sweetness and suppress the intensity of some bitter compounds. Recent studies have analyzed umami taste interaction with salty and sour tastes from a temporal perspective. One study showed that when MSG is combined with either NaCl (salty taste) or lactic acid (sour taste) the duration of the umami sensation was altered. IMP and NaCl decrease the duration of umami taste, whereas MSG suppresses the duration of the sourness of lactic acid.
Umami sensation increases salivary secretion, more so than sour stimuli. Saliva helps dissolve taste substances from foods and protects taste sensation. Reduced salivation can alter taste perception, leading to poor appetite, weight loss, and poor health. Umami taste stimulation has been used to improve salivary secretion in elderly patients with deficient umami taste sensation.
Glutamate also plays a role as a signaling molecule in the gastrointestinal tract. Glutamate receptors have been found in the stomach and gut, and studies suggest that glutamate may enhance food signaling to the brain by stimulating the vagus nerve and the secretion of neuroendocrine hormones and digestive juices that support protein digestion. Furthermore, umami sensation interacts with odors, enhancing the intensity of aromas like chicken soup or celery, especially when these foods are swallowed.
Glutamate enhances appetitive sensorial traits in a complex food context while masking negative ones. At the same time umami is involved in the regulation of various gastrointestinal functions. This could partially explain why there is no need in Japanese traditional diets to use large amounts of animal fat or meats for optimal palatability-the meat-like sensation of traditional Japanese dishes with umami is sufficient.
Read also: Walnut Keto Guide
Washoku: The Essence of Japanese Dietary Culture
The traditional dietary cultures of Japan are collectively known as Washoku. In 2013, Washoku was added to the UNESCO list of Intangible Cultural Heritage. The guiding principles of Washoku are a staple food-rice-which is complemented by a variety of side dishes, soup, and pickles. Together these form the basic structure of a meal, customarily eaten using chopsticks and wooden bowls. This style of eating a main staple food with side dishes interchangeably, mixes, and harmonizes all flavors inside the mouth. Small bites, due to the use of chopsticks, together with the combination of foods inside the mouth seem to contribute to satiety. There is evidence showing that multiple alternation of foods decreases food consumption at the end of the meal. The relatively small portion size of the main and side dishes is another trait that helps to avoid overeating, since studies have shown that big portions encourage the consumption of larger meals. Frequent intake of soup by Japanese men has been correlated with a lower body mass index (BMI), waist circumference, and waist-to-hip ratio, all physical factors related to obesity. Others have also demonstrated that soups have a satiating effect.
The core flavor of Japanese food is umami taste from dashi stock, which is the base of many Japanese recipes. Cooks in Japan have mastered the techniques of extracting umami substances from dried kelp and dried bonito flakes in dashi stock with traditional flavoring products, such as soy sauce, miso, and vinegar to heighten the distinctive flavor of many ingredients. Water is another important ingredient in traditional diets. As rivers in Japan are short, water is soft and quite free of impurities. Thanks to the work of culinary professionals at the Japanese Culinary Academy, it is known that soft water functions not only to reduce or remove bitterness but it also efficiently brings out the umami sensation from dried kelp and dried bonito flakes.
This dashi stock is used to boil vegetables and serves two functions: It reduces the volume and increases the palatability of vegetables. This facilitates the inclusion of larger quantities of vegetables within the Japanese menu and thereby increases their consumption, which has been shown to lead to a lower the risk of cardiovascular diseases (CVD) and all causes of mortality and morbidity. Moreover, the main cooking methods in Washoku are steaming, boiling, and stewing, thereby enhancing the water content of Japanese dishes. This incorporation of water into food seems to be more efficient that drinking water to decrease the overall intake of energy in a meal.
The style of eating in Washoku-a large variety of foods, small portions, the inclusion of soups, abundant vegetables, the cooking method, the large content of water, and the effective usage of umami taste-promotes not only the pleasant experience of eating, combined with the large incorporation of bioactive compounds from vegetables, but also ensures an adequate signal for satiety that prevents overeating.
Another parameter to take into account as a potential healthful trait of the Japanese diet is the frequent consumption of fish. Side dishes in Washoku include many types of fish that are a rich source of high quality protein as well as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), ω-3 fatty acids that are believed to be beneficial for health. Soy bean-based foods, in the form of fermented miso and tofu, are common in Japanese traditional diets, and are known to reduce blood pressure and blood glucose. Additional factors to consider are the energy and sodium content of the Japanese diet. Several studies have found consistent low calorie ingestion among men and women from Japan, compared to those in China, the United States, Italy or the UK. This may partly explain the lower BMI among Japanese compared to other populations.
Read also: Weight Loss with Low-FODMAP
In reference to sodium, a high urinary excretion has been reported for Japanese people, accompanied by a high estimated sodium consumption-between 11 mg for men and 9 mg for women daily. Although salt intake in Japan, especially in certain regions, has considerably decreased from the 1950s and 1960s, the current consumption is still higher than the recommended amount to reduce mortality by stroke (<6 mg per day). The most common dietary sources of sodium in the Japanese diet are miso soup and salted vegetables as well as soy sauce and commercially processed fish or seafood. However, in spite of a high sodium intake, Japanese have an overall low incidence of CVD, probably due to a higher potassium intake with vegetables. Finally, families strengthen their bonds by sharing meals together, which is important for usual communication.
Key Components of the Traditional Japanese Diet
The traditional Japanese diet is a whole-foods-based diet rich in fish, seafood, and plant-based foods with minimal amounts of animal protein, added sugars, and fat. It’s based on traditional Japanese cuisine, also known as “washoku,” which consists of small dishes of simple, fresh, and seasonal ingredients. This eating pattern is rich in nutrients and may provide numerous health benefits, including improved weight loss, digestion, longevity, and overall health. The traditional Japanese diet consists of minimally processed, seasonal foods served in a variety of small dishes. This style of eating emphasizes dishes’ natural flavors rather than masking them with sauces or seasonings. The diet is rich in steamed rice, noodles, fish, tofu, natto, seaweed, and fresh, cooked, or pickled fruits and vegetables but low in added sugars and fats. It may also contain some eggs, dairy, or meat, although these typically make up a small part of the diet. The traditional Japanese diet resembles the Okinawan diet, the historical eating pattern of those living on the Japanese island of Okinawa, but includes significantly more rice and fish. It contrasts with modern Japanese cuisine, which has strong Western and Chinese influences and includes larger amounts of animal protein and processed foods.
Japanese meals generally consist of a staple food combined with a soup, a main dish, and a few sides.
- Staple food: steamed rice or soba, ramen, or udon noodles
- Soup: typically a miso soup made with seaweed, shellfish, or tofu and vegetables in a fermented soybean stock - though vegetable or noodle soups are other popular options
- Main dish: fish, seafood, tofu, or natto with optional small amounts of meat, poultry, or eggs
- Side dishes: vegetables (raw, steamed, boiled, sautéed, grilled, or pickled), wild plants, seaweed, and raw or pickled fruit
Japanese meals are known for their rich umami flavor. Visual appeal is another important aspect of the traditional Japanese diet. Dishes tend to be eaten in small bites with chopsticks, as this method is believed to create a rich harmony of flavors. Hot green tea or cold barley tea are the beverages of choice, while alcoholic drinks like beer and sake are typically reserved for dinner. Snacks are uncommon and seldom eaten.
Health Benefits of the Japanese Diet
The traditional Japanese diet is linked to an array of health benefits.
- Rich in nutrients and beneficial compounds: The traditional Japanese diet is naturally rich in various nutrients, including fiber, calcium, potassium, magnesium, iron, and vitamins A, C, and E. Vegetables contribute to the nutrient density of this diet and are often cooked in dashi, a dried fish and sea vegetable based stock. This reduces their volume and enhances their flavor, making it easier to eat large amounts. The diet also offers good amounts of seaweed and green tea. Both are great sources of antioxidants, which are beneficial compounds that protect your body against cellular damage and disease. The many fish- and seaweed-based dishes included in this diet provide long-chain omega-3 fats, which promote brain, eye, and heart health.
- May improve your digestion: Seaweed, soybeans, fruits, and vegetables are naturally rich in fiber, a nutrient that aids your digestion. Insoluble fiber moves food through your gut and adds bulk to stool, reducing your risk of constipation. These foods also boast soluble fiber, which feeds the beneficial bacteria in your gut and helps reduce the space available for harmful bacteria to multiply. When gut bacteria feed on soluble fiber, they produce short-chain fatty acids (SCFAs), which may reduce inflammation and symptoms of irritable bowel syndrome (IBS), Crohn’s disease, and ulcerative colitis. The pickled fruits and vegetables commonly eaten on this diet are a great source of probiotics. These beneficial bacteria promote gut health and reduce digestive symptoms like gas, bloating, constipation, and diarrhea.
- May promote a healthy weight: The traditional Japanese diet is rich in vegetables, has small portion sizes, and is naturally low in added sugar and fat. These factors all contribute to a low calorie count. Japanese culture encourages eating until only 80% full. This practice deters overeating and may contribute to the calorie deficit needed to lose weight. Research shows that the fiber-rich vegetables, soy foods, and soups typical of the traditional Japanese diet may help reduce appetite and boost fullness, thus promoting weight control. Alternating between dishes, as is common during traditional Japanese meals, may reduce the total amount of food eaten per meal.
- May protect against chronic diseases: The traditional Japanese diet may safeguard against conditions like type 2 diabetes and heart disease. It’s naturally rich in fish, seaweed, green tea, soy, fruits, and vegetables but low in added sugar, fat, and animal protein - all factors believed to protect against heart disease. In fact, Japanese people’s risk of heart disease remains unexpectedly low despite their high salt intake, which typically raises heart disease risk. In a 6-week study in 33 men following the traditional Japanese diet, 91% experienced significant reductions in risk factors for type 2 diabetes, including excess weight and high LDL (bad) cholesterol levels. Plus, the high green tea intake encouraged on this diet may protect against Alzheimer’s disease, Parkinson’s disease, and certain types of cancer.
- May help you live longer: Japan has one of the world’s highest life expectancies, which many experts attribute to the traditional Japanese diet. The Japanese island of Okinawa is considered a Blue Zone, which is a region with extremely high longevity. Keep in mind that the Okinawa diet focuses heavily on sweet potatoes and features less rice and fish than the traditional Japanese diet. In a 15-year study in over 75,000 Japanese people, those who closely followed the traditional Japanese diet experienced up to a 15% lower risk of premature death compared with those eating a Westernized diet. Experts link this increased lifespan to the traditional Japanese diet’s emphasis on whole, minimally processed foods, as well as its low added fat and sugar content.
Foods to Include and Limit
The traditional Japanese diet is rich in the following foods:
- Fish and seafood: All types of fish and seafood can be included. These can be steamed, baked, grilled, or raw - as is the case with sushi and sashimi.
- Soy foods: The most common are edamame, tofu, miso, soy sauce, tamari, and natto.
- Fruit and vegetables: Usually, fruits are eaten raw or pickled while vegetables are steamed, sautéed, pickled, simmered in broth, or added to soups.
- Seaweed: Sea vegetables are a big part of the traditional Japanese diet. They’re usually eaten raw or dried.
- Tempura: This light dough is made by mixing wheat flour with iced or sparkling water. It serves as a batter for deep-fried seafood and vegetables.
- Rice or noodles: Steamed rice is a staple in a traditional Japanese diet. Other popular options include soba, ramen, or udon noodles served chilled or in a hot broth.
- Beverages: Hot green tea and cold barley tea are the main beverages, though beer and sake may be served with dinner.
Small amounts of red meat, poultry, eggs, and dairy may also be included. However, these foods don’t comprise a large part of the traditional Japanese diet.
The traditional Japanese diet minimizes the following foods:
- Dairy: butter, milk, cheese, yogurt, ice cream, etc.
- Red meat and poultry: beef, pork, chicken, duck, etc.
- Eggs: boiled, fried, as an omelet, etc.
- Excess fats, oils, and sauces: margarine, cooking oils, dressings, fat-rich sauces, etc.
- Baked goods: bread, pita, tortillas, croissants, pie, brownies, muffins, etc.
- Processed or sugary foods: breakfast cereals, granola bars, candy, soft drinks, etc.
Moreover, snacks are uncommon on this diet, which inherently limits popular snack foods like chips, popcorn, trail mix, and crackers. Desserts may be included on the traditional Japanese diet - but they rely on natural ingredients, such as fruit, matcha, or red bean paste, rather than added sugars.
Sample Japanese Diet Menu
Here’s a typical 3-day menu for the traditional Japanese diet:
Day 1
- Breakfast: miso soup, steamed rice, natto, and seaweed salad
- Lunch: soba noodles in a dashi-based broth, grilled tuna, kale salad, and boiled vegetables
- Dinner: udon noodle soup, fish cakes, edamame, and vegetables marinated in vinegar
Day 2
- Breakfast: miso soup, steamed rice, an omelet, dried trout, and pickled fruit
- Lunch: clam soup, rice balls wrapped in seaweed, marinated tofu, and a cooked-vegetable salad
- Dinner: miso soup, sushi, seaweed salad, edamame, and pickled ginger
Day 3
- Breakfast: udon-noodle soup, a boiled egg, shrimp, and pickled vegetables
- Lunch: shiitake-mushroom soup, rice cakes, seared scallops, and steamed vegetables
- Dinner: miso soup, steamed rice, vegetable tempura, and salmon or tuna sashimi
The Okinawan Diet and the "Hara Hachi Bu" Principle
Okinawa, Japan, is a "blue zone" with an exceptionally long-lived population. Okinawans over the age of 65 enjoy the world’s highest life expectancy: Men are expected to live to about 84, while women are expected to live to almost age 90. The average daily intake of an Okinawan is only about 1,900 calories, significantly less than the average number of calories consumed by a typical American.
A key practice in Okinawa is hara hachi bu - a Confucian-inspired adage reminding people to stop eating when their stomachs are 80 percent full. This encourages moderation, awareness, and gratitude while slowing down at mealtimes. While research specifically on hara hachi bu is limited, evidence suggests it can reduce total daily calorie intake and is associated with lower long-term weight gain and lower average body mass index (BMI). It also aligns with healthier meal-pattern choices, such as increased vegetable consumption.
Hara hachi bu shares principles with mindful and intuitive eating, encouraging a stronger connection with internal hunger and satiety cues, and may reduce emotional eating and enhance overall diet quality. Sustainable health changes are far easier to maintain in the long-term. This may improve health and prevent weight regain, which can be a risk for those who lose weight through traditional diet approaches.
Implementation of "Hara Hachi Bu"
Here are a few tips to try:
- Check in with your body before eating: Ask yourself: Am I truly hungry? And if so, what kind of hunger is it - physical, emotional, or just habitual?
- Eat without distractions: Step away from screens and give your meal your full attention.
- Slow down and savor each bite: Eating should be a sensory and satisfying experience.
- Aim to feel comfortably full, not stuffed: Eating until you're around "80% full" means you should feel comfortably satisfied rather than stuffed.
- Share meals when you can: Connection and conversation are part of what makes food meaningful.
- Aim for nourishment: Ensure your meals are rich in vitamins, minerals, fibre and energy.
- Practice self-compassion: There's no need to eat "perfectly".
It is important to note that hara hachi bu is not meant to be a restrictive eating approach, but a way of being aware of your body.
Practical Steps to Incorporate Japanese Diet Principles
The Japanese way of eating emphasizes moderation and variety. Worrying less about diet and practicing moderation and variety consistently can help meet health goals without excessive concern about specific foods.
- Eat with your eyes: Present food with beautiful portion control in pretty little dishes and plates to encourage slower eating and savoring every bite.
- Portion power: Serve food on separate small plates and bowls instead of on one big plate.
- Rice foundation: Include a small bowl of rice with almost every meal. For extra health benefits, serve rice the Japanese way, cooked and eaten with no butter or oil.
- Veggie delight: Include as many as four or five different varieties of vegetables in a single meal. Veggies are served simmered in seasoned broth, stir-fried in a small bit of canola oil, or lightly steamed.
- A good catch: Eat fish, especially fatty fish, as a great source of omega-3 fatty acids.
- Soy good: Consume natural soy products like tofu and edamame beans as a great protein alternative to red meat.
- Delicious desserts: Enjoy an assortment of seasonal fruits.
Recipe Inspirations
- Kinpira (Burdock and Carrot): A classic Japanese home-cooked dish featuring burdock and carrots sautéed with red peppers and roasted sesame seeds.
- Beef Over Rice: An abbreviated version of sukiyaki, with thinly sliced beef and vegetables in a sweet soy broth, spooned over hot cooked rice.
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