慢性腎臓病患者のたんぱく質摂取量と血中尿素窒素の関連に食物繊維摂取量が影響する可能性 ー慢性腎臓病患者274名の解析から、より柔軟で持続可能な食事療法への手がかりー

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2026-10-13 東京科学大学

東京科学大学の研究チームは、慢性腎臓病患者274人のデータを解析し、食事から摂取するたんぱく質の量と、血中尿素窒素(BUN)濃度との関係に、食物繊維の摂取量が影響する可能性を示した。BUNは、たんぱく質の代謝で生じる尿素に由来し、腎機能が低下すると血中濃度が上昇しやすい。このため、慢性腎臓病の食事療法では、病状や栄養状態に応じたたんぱく質摂取量の管理が重要となる。解析では、全体として、たんぱく質の摂取量が多いほどBUN濃度が高い傾向が認められた。一方、食物繊維の摂取量が多い群では、この関連が明確には認められなかった。食物繊維が腸内細菌による尿毒素産生や尿素の排泄に関与する可能性が背景にある。ただし、本研究は一時点のデータを用いた観察研究であり、食物繊維を増やすことでBUNが低下することを証明したものではない。今後、長期的な追跡研究を通じて、腎機能や栄養状態に配慮した、より柔軟で継続可能な食事療法につながる知見が期待される。

慢性腎臓病患者のたんぱく質摂取量と血中尿素窒素の関連に食物繊維摂取量が影響する可能性 ー慢性腎臓病患者274名の解析から、より柔軟で持続可能な食事療法への手がかりー
図1. 本研究で検証した関連性

<関連情報>

食物繊維は慢性腎臓病患者におけるタンパク質摂取量とBUN値の関連性を弱める Dietary Fiber Attenuates the Association between Protein Intake and BUN in Patients with CKD

Nobuhisa Morimoto,Tamami Fujiki,Shintaro Mandai,Fumiaki Ando,Takayasu Mori,Koichiro Susa,Shotaro Naito,Eisei Sohara,Tatsuhiko Anzai,Kunihiko Takahashi,Wataru Akita,Akihito Ohta,Shinichi Uchida,Soichiro Iimori
Kidney360  Published:August 21, 2026
DOI:10.34067/KID.0000001350

Abstgract

Background:
While greater protein intake may contribute to BUN levels in patients with CKD, few studies have investigated whether dietary fiber modifies the association. We aimed to examine the effect modification of the association between protein intake and BUN by dietary fiber in patients with non-dialysis-dependent CKD.

Methods:
We included 274 patients (median age 72 years; 34% women) at three hospitals in Japan. Food group and nutrient intakes were estimated using a validated diet history questionnaire. We compared food group intake by dietary fiber tertiles. Multiple linear regression assessed the association between protein intake and BUN, adjusting for potential confounders. We performed stratified analyses by dietary fiber tertiles and interaction analyses.

Results:
The median (interquartile range) BUN was 24 (19–37) mg/dL, and the mean (standard deviation (SD)) estimated glomerular filtration rate was 33 (16) mL/min/1.73m2. The mean (SD) protein and fiber intakes were 39 (8) and 6.5 (2.2) g/1000 kcal/day, respectively. Patients with higher fiber intake had greater intake of fruits, vegetables, fish, and eggs than those with lower fiber intake. Protein intake was positively associated with natural log-transformed BUN (regression coefficient (β) = 0.05, 95% CI: 0.01 to 0.08, for one SD increase in protein intake). The association appeared stronger in the low-fiber (β = 0.08, 95% CI: 0.02 to 0.14) and medium-fiber groups (β = 0.08, 95% CI: 0.02 to 0.13), whereas it was not significant in the high-fiber group (β = 0.01, 95% CI: -0.03 to 0.06) (P for interaction = 0.10).

Conclusions:
The positive association between protein intake and BUN was attenuated in patients with high fiber intake, who had higher intakes of fruits, vegetables, fish, and eggs. Further studies are warranted to examine whether more liberal protein restriction is feasible in BUN management by increasing dietary fiber.

医療・健康
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