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What are the common misunderstandings about getting enough dietary fibre?

This answer is a draft. It stays unpublished until legal review and source verification are complete.

The answerThe biggest misunderstanding is "a green salad every day is enough." Leafy salads contain surprisingly little fibre, and Japanese intake falls short of the target by about 1–2 g a day (roughly 2 g for men; women are close to the target). The efficient route is to switch your staple to brown rice, barley or wholemeal, and to eat more beans, mushrooms, seaweed and root vegetables and potatoes.

Dietary fibre is the classic "nutrient people do not get enough of" in every country, and Japan is no exception. Here we set out the gap between the national target and actual intake, and the easiest ways to add fibre at a Japanese table.

In numbers

ItemFigureSource
Target (ages 18–64)Men 21 g or more / women 18 g or more (per day)Dietary Reference Intakes for Japanese (2025 edition)
Actual intake (average, age 20 and over)About 18–19 g (men just over 19 g, women just over 18 g)National Health and Nutrition Survey (2023)
Intake in the 1950s (estimate)Over 20 gVarious nutrition-history studies
WHO/FAO guide25 g or moreWHO
Food (typical serving)Dietary fibre
White rice, cooked, 150 g0.5 g
Brown rice (*genmai*), cooked, 150 g2.1 g
Rice with 30% pressed barley (*oshimugi*), cooked, 150 gapprox. 2.5 g
Natto (fermented soybeans), 1 pack (45 g)3.0 g
Boiled soybeans, 50 g3.5 g
*Kinpira gobō* (stir-fried burdock root; 50 g burdock)2.9 g
Simmered *hijiki* seaweed (10 g dried)5.2 g
Lettuce, 50 g0.6 g
Apple, half (150 g with skin)2.1 g
[Verify] Check the target against the "Dietary Reference Intakes for Japanese (2025 edition)," the intake against the latest year of the National Health and Nutrition Survey, and the food figures against the Standard Tables of Food Composition in Japan (8th revised edition), 2023 supplement.

Misunderstanding 1|I eat salad every day, so I am fine

A plate of lettuce gives under 1 g. Root vegetables, beans, mushrooms, seaweed and potatoes are the main sources, and changing your staple makes the biggest difference.

Misunderstanding 2|Vegetable juice does the job

In most vegetable juices, the fibre is largely lost in processing. Look at the "dietary fibre" (食物繊維) figure on the label: many products give about 1–2 g per bottle.

Misunderstanding 3|The more fibre, the better

Increasing it suddenly brings gas and bloating. Large amounts from supplements are generally described as possibly affecting the absorption of minerals. From food, a little at a time is the rule.

Misunderstanding 4|Switching white rice for brown is hard on the digestion

Chew well, soak the rice longer, or mix in partly milled rice (分づき米, *buzuki-mai*) or barley. If your digestion is weak, or for older people, starting with barley rice (麦飯, *mugi-meshi*) or partly milled rice is the realistic route.

Misunderstanding 5|Eat fibre and your bowels will always improve

Fibre comes in soluble (seaweed, fruit, barley) and insoluble (grain husks, beans, vegetables) forms, and without enough fluid, stools can become harder. Take it together with water. If symptoms continue, see a doctor.

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Sources

https://www.mhlw.go.jp/stf/newpage_44138.html

https://www.mhlw.go.jp/stf/newpage_47433.html

https://www.mext.go.jp/a_menu/syokuhinseibun/mext_00001.html

⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.

About this article

What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.

This is general information. Results vary from person to person and depend on your own conditions and surroundings.

Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.

This article is not meant to diagnose or manage any specific medical condition. If you are worried about your health, see a doctor rather than relying on your own judgement.

Sources

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