Fiber: the one most of us come up short on

Fiber is the nutrient nobody plans a meal around. There's no dramatic deficiency behind it, no single food that fixes it, and no week where you can watch it going wrong — which is exactly how a household list misses it for months at a stretch. And it usually misses most of the table at once.

The targets still belong to people, though. The teenager and the grandmother in the same kitchen are aiming at numbers nowhere near each other.

How much fiber, by age

Everyone in your household gets their own daily targets for their age and sex, and fiber is one of them, alongside calories and protein. In grams a day:

• children 4 to 8: 25 g
• ages 9 to 13: 31 g for boys, 26 g for girls
• ages 14 to 18: 38 g for boys, 26 g for girls
• ages 19 to 50: 38 g for men, 25 g for women
• ages 51 and over: 30 g for men, 21 g for women

A boy of 14 already needs more than his mother. A girl's target barely moves from 9 to 50. So a teenage boy needs as much fiber as any adult at the table, and he is very rarely the one planning the week.

The Institute of Medicine's dietary reference intakes also put fiber at 28 g a day during pregnancy and 29 g while nursing.

Most of us don't get there

This is the rare nutrient where falling short is the normal case rather than the exception. Among adults, the Dietary Guidelines for Americans 2020-2025 stated it flatly: more than 90 percent of women and 97 percent of men do not meet recommended intakes for dietary fiber.

That is not a sentence about willpower. Fiber comes from whole grains, legumes, fruit and vegetables, and nowhere else. Meat, fish, eggs, milk, cheese, oil: none of them carry any. Neither does the refined side of the grain aisle, where it was already milled out. A week's shopping can be careful, well cooked and full of good food, and still leave fiber almost nowhere to come from.

Where it comes from

The foods highest in fiber ranks the whole catalog. Two things to know before you read it: the ranking is gram for gram, so something you eat by the spoonful sits next to something you eat by the bowlful, and dried beans are weighed dry, as they sit in the bag rather than after soaking.

Seeds sit at the very top, small and concentrated — chia seeds and flaxseed — and under them runs a long stretch of dried beans and peas: dried kidney beans, green split peas and dried black beans. The whole grains come further down, where hulled barley and bulgur both make the list. Rolled oats and brown rice aren't on that ranking at all, but they belong in the same cupboard. And the freezer counts as much as the produce drawer, since frozen broccoli and frozen blueberries were picked at their best and then stopped there. Each of those pages carries its own amount, so this post doesn't restate one.

How Mirabelly counts it

Fiber isn't a footnote here. Every person you add to your household gets their own fiber target, and fiber gets its own row on the coverage scorecard — met, marginal or low — exactly like iron or calcium. That placement is the point. Fiber is easy to treat as something you hope came along with everything else. Here it's a line your week has to answer.

Mirabelly watches which kind of fiber you're getting, too. Fiber isn't one substance but a family of them, so the list sorts it into four kinds — viscous soluble, fermentable, insoluble bulking and resistant starch — and checks how many of the four a week actually covers, not only the grams.

Then it builds one shared weekly grocery list that covers everyone's targets at once, and when a week comes up short on fiber for someone, it says so and names them instead of rounding the household up. How it works walks through the rest of what happens between your household and your week.