Dysphagia Knowledge Hub — 吞嚥困難知識庫

IDDSI Level 6 (Soft and Bite-Sized): Knife Cut Test, Qualifying Foods, and Prescribing Criteria

What Is IDDSI Level 6?

IDDSI Level 6 — Soft and Bite-Sized — is the highest modified food texture level in the IDDSI framework before Level 7 (Regular). It describes foods that are soft, tender, and moist enough to be broken down with the tongue and palate or with minimal dental contact, without requiring full masticatory effort. Foods must be served in pieces no larger than 1.5 cm in any dimension for adults (0.8 cm for pediatric patients).

Level 6 is often described as the “almost normal diet” level. Patients at this level can eat recognisable food pieces, participate in shared mealtimes with greater dignity than at lower texture levels, and access a much wider range of naturally soft foods without industrial modification. However, it is not a default or minimal-intervention level — it requires deliberate food selection, correct preparation, and clinical confirmation that the patient can safely manage bite-sized pieces.

The Knife Cut Test

The IDDSI knife cut test is the primary verification method for Level 6 foods:

Take a standard table knife (not a serrated knife, not a sharp chef’s knife — a standard flat-edged dinner knife).
Apply firm, even pressure to the food piece using the side of the blade — do not use a cutting motion.
Observe the result.

Level 6 pass: The food yields and breaks apart under the pressure of the side of the knife blade without any cutting action. It does not require the blade edge to cut.

Level 6 fail (too firm): The food requires a cutting motion or significant force to break. This food would typically qualify as Level 7 (Regular) if it still has appropriate texture, or would require further cooking.

Level 6 fail (too soft/wet): The food collapses into a puree or paste under the pressure. This food may be at Level 4 or 5 — it is too soft to maintain bite-sized integrity.

The knife cut test assesses both softness and structural integrity. A food that is soft enough to pass the pressure test but fragments into shreds, strings, or uneven lumps also fails — consistent particle size and cohesion matter for safe oral management.

Maximum Particle Size

All Level 6 food pieces must be pre-cut to a maximum of 1.5 cm in any single dimension (adult). This is approximately the width of a thumbnail. No piece should exceed this size regardless of how soft the food is, because piece size determines the bolus volume that must be managed in a single swallow.

Caregivers and food service staff frequently underestimate piece size. A practical approach is to:

Use a clean ruler or size guide during training
Cut food to a consistent size grid before plating
Verify a representative sample from each batch rather than trusting visual estimation alone

Pieces that are correctly sized but not uniformly cut present a problem when smaller fragments fall below Level 5 size (4 mm). Level 6 meals should be composed of pieces within a consistent range, not a mixture of large and minute fragments.

Foods That Qualify for Level 6

The following foods are commonly appropriate at Level 6 when correctly prepared:

Proteins: Tender poached, steamed, or slow-cooked fish (skinless, boneless); soft-boiled or poached eggs; tofu (silken or firm, depending on preparation); tender braised chicken thigh (skin removed, cut across the grain); well-cooked legumes (lentils, soft-cooked beans).

Vegetables: Steamed or roasted courgette, soft-cooked carrot, baked beetroot, roasted sweet potato, soft-cooked broccoli florets (no stalk), cooked spinach or chard.

Grains and starches: Soft-cooked pasta (slightly beyond al dente), soft white rice, well-cooked polenta cut into soft pieces, gnocchi cooked until tender.

Fruit: Ripe banana, soft canned peach or pear (drained), ripe mango, cooked apple.

Dairy: Soft cheese (ricotta, brie without rind, cream cheese portions), soft set custard cut into pieces, firm yoghurt served in portions.

Foods That Fail Level 6

Foods that are too firm: Raw or lightly cooked vegetables (carrot, broccoli, green beans), most cuts of unmodified red meat, crusty bread, rice crackers, hard cheese.

Foods with mixed texture: Foods with a soft exterior and harder interior (e.g., stuffed pasta with firm filling), foods with coatings (battered or crumbed items where the coating firms after cooking), fruit with skins.

Foods that fragment unpredictably: Cooked chicken breast (tends to shred along muscle fibres), flaky fish without a binding sauce, crumbly cake without enough moisture.

Foods with hidden hazards: Seeds, pips, bones, cartilage, hard garnishes, nut pieces, and toothpicks — all of which can be concealed in otherwise appropriate food.

Level 6 vs Level 5: Prescribing Decision

The Level 5 (Minced and Moist) versus Level 6 (Soft and Bite-Sized) decision is one of the most frequent clinical prescribing choices in dysphagia management.

Prescribe Level 5 when:

The patient lacks the tongue strength or coordination to manage 1.5 cm pieces
The patient has a history of pocketing food or missing oral clearance on larger pieces
Instrumental assessment shows residue or aspiration with structured food pieces
The patient fatigues rapidly — Level 5’s smaller pieces require less total oral processing per bite

Prescribe Level 6 when:

The patient can manage bite-sized pieces with intact oral control
Tongue-palate pressure is sufficient to break soft food without jaw movement
The patient has progressed successfully from Level 5 with supervised trials
Quality of life and mealtime participation are clinical priorities and risk assessment supports the step-up

As with all IDDSI level decisions, prescribing should be based on clinical assessment — ideally including SLP review and where indicated, instrumental evaluation. Level 6 is not appropriate simply because a patient “seems to eat well” at the bedside without structured assessment.

Summary

IDDSI Level 6 (Soft and Bite-Sized) defines foods that are soft enough to yield under the side of a table knife, served in pieces of maximum 1.5 cm. It is the closest-to-normal modified texture level and offers significantly greater mealtime participation than lower levels. Verification uses the knife cut test. Foods must be soft, moist, and cohesive — not firm, fragmented, or of mixed texture. The prescribing decision between Level 5 and Level 6 should be grounded in clinical assessment of oral processing capacity, swallow safety on structured pieces, and fatigue profile.