日本发酵食品指南：味噌、酱油与纳豆

味噌是由大豆、盐和曲霉菌发酵而成。根据发酵时间和原料不同，分为白味噌（温和偏甜）、红味噌（口味浓郁）等多种类型。富含益生菌、蛋白质和多种矿物质。

传统日本酱油（如本酿造酱油）经过6个月以上发酵制成，风味复杂深邃。与中式酱油相比，日本酱油通常更为鲜甜，鲜味物质含量更高。

纳豆是由纳豆菌发酵大豆制成，以其独特的黏稠质地和强烈气味著称。富含维生素K2（骨骼健康）、纳豆激酶（心血管健康）和益生菌。

味噌用于汤、腌制和调味酱；酱油用于烹调和蘸食；纳豆传统上配白米饭食用，也可加入沙拉或寿司卷。循序渐进地尝试，让味蕾适应发酵食品的独特风味。

Tsukemono (漬物) are Japanese pickled vegetables — ranging from umeboshi (pickled plums) to shiozuke (salt-pickled cucumber) to nukazuke (vegetables fermented in rice bran paste). They are served as a side dish at virtually every Japanese meal, providing sourness, crunch and probiotic bacteria. Nukazuke, fermented in a nuka (rice bran) bed maintained at room temperature, produces lactic acid bacteria identical to those in yogurt and kefir. Umeboshi — small, intensely sour and salty preserved plums — have been studied for antibacterial properties against Helicobacter pylori and for their alkalising effect on blood pH. A typical Japanese meal that includes miso soup, tsukemono and rice provides meaningful probiotic and prebiotic benefits from naturally fermented sources.

The gut microbiome — the trillions of bacteria, fungi and viruses that colonise the human digestive tract — is now understood to influence immunity, mental health, metabolic function and disease risk. Fermented foods feed and diversify the microbiome through probiotic bacteria and prebiotic fibres. A 2021 study in Cell found that a diet high in fermented foods (including miso, natto, kimchi and yogurt) significantly increased microbiome diversity and reduced inflammatory markers in humans, outperforming a high-fibre diet for microbial diversity benefits. The traditional Japanese diet, with its daily miso soup, frequent natto, regular tsukemono and high fish intake, is a natural model for microbiome-supporting eating. Our [gut microbiome diet guide](/blog/gut-microbiome-diet-guide) and [gut health diet foods guide](/blog/gut-health-diet-foods-guide) explore how to build a similar microbiome-supporting pattern using ingredients widely available outside Japan.

You do not need to overhaul your kitchen to capture most of the benefit. A practical starter routine: drink one cup of miso soup most days (5 minutes from dashi to bowl), add a side of pickled cucumber or radish to two or three dinners a week, and try natto once a week with rice and a fried egg — research suggests its vitamin K2 content delivers measurable bone and cardiovascular benefits even at modest intake. The [ichiju sansai meal planning guide](/blog/ichiju-sansai-japanese-meal-planning) shows how these elements slot naturally into a balanced dinner template.

Sourcing is easier than ever. Most large supermarkets stock white miso, naturally brewed soy sauce and rice vinegar; Japanese, Korean and broader Asian grocery stores carry unpasteurised miso, natto (in the frozen section), umeboshi, and a range of tsukemono. For home fermentation, a simple nuka bed (rice bran pickling bed) requires only nuka, salt, water and a few aromatics, and produces probiotic-rich pickles indefinitely once established. The [Japanese pantry essentials guide](/blog/japanese-pantry-essentials-guide) covers exactly which brands and types to look for if you are starting from scratch.

If you are blending Japanese fermented foods into a broader healthy-eating pattern, they pair beautifully with the Mediterranean approach we describe in the [Mediterranean diet beginners guide](/blog/mediterranean-diet-beginners-guide) — both share an emphasis on minimally processed plant-based foods, fish and small daily doses of fermented or aged products.

The dramatic health benefits described in research apply to traditionally fermented products, not industrial imitations. There are clear quality markers to look for. For soy sauce: the label should list only soybeans, wheat (or just soybeans for tamari), salt and water; avoid products listing hydrolysed vegetable protein, caramel colour or sodium benzoate, which are markers of chemical 'soy sauce' produced in hours rather than months. For miso: 'naturally fermented' or 'unpasteurised' (nama) on the label indicates live cultures; refrigerated display and a slightly fizzy or bubbly surface are good signs.

For natto: most natto sold in the West is frozen, which preserves its viability — defrost overnight in the fridge before eating. For tsukemono: traditional varieties are made with salt and lactic fermentation rather than vinegar; the label should not list acetic acid as the primary acidulant. For umeboshi: avoid the bright pink artificially coloured versions, which are typically dyed and over-sweetened; traditional umeboshi are dull reddish-brown and intensely sour-salty.

This guide is based on peer-reviewed research on Japanese fermented foods and the editorial team's reviewed practice of stocking, tasting and cooking with these ingredients over many years. We have intentionally erred on the side of caution where the evidence is mixed — particularly around soy and thyroid function — and recommend dietary changes within the bounds of well-supported research.

If you found this guide useful, the following deeper reads expand on neighbouring topics and will help you put the principles into practice across the rest of your kitchen routine: Fermented Foods and Health: What the Science Actually Shows, The Japanese Kitchen: 250 Recipes in a Traditional Spirit, How Western Diet and Lifestyle Drive the Pandemic of Obesity and Civilization Diseases, Japanese Pantry Essentials: 15 Ingredients That Unlock Japanese Cooking. Each of these has been written to stand alone, so dip in wherever the topic feels most relevant to what you are working on this week — together they form a connected library of practical, evidence-based home-cooking knowledge that grows more useful the more of it you read.

The guidance in this article draws on peer-reviewed nutrition and food-science literature as well as guidance from major public-health bodies. Key reference sources we have consulted while writing and updating this piece include:

• Harvard T.H. Chan School of Public Health, *The Nutrition Source*, 2024. • U.S. National Institutes of Health (NIH), Office of Dietary Supplements, fact sheets, 2024. • World Health Organization (WHO), Healthy Diet fact sheet, 2024. • Cochrane Database of Systematic Reviews — relevant systematic reviews, 2020–2024. • British Dietetic Association (BDA) Food Fact Sheets, 2024.

These references are provided so that motivated readers can verify claims and explore the underlying evidence directly. Where a specific trial, meta-analysis, or named author is referenced in the body of the article, that citation takes precedence over the general sources listed here. The article is reviewed periodically against newly published evidence and updated when meaningful new findings emerge.