Dietary Fiber, Genetic Variations of Gut Microbiota-derived Short-chain Fatty Acids, and Bone Health in UK Biobank

Abstract

Context: Dietary fiber intake may relate to bone health.

Objective: To investigate whether dietary fiber intake is associated with bone mineral density (BMD), and the modification effect of genetic variations related to gut microbiota-derived short-chain fatty acids (SCFAs).

Design: The associations of dietary fiber intake with estimated BMD derived from heel ultrasound and fractures were assessed in 224 630 and 384 134 participants from the UK Biobank.

Setting: UK Biobank.

Main outcome measures: Estimated BMD derived from heel ultrasound.

Results: Higher dietary fiber intake (per standard deviation) was significantly associated with higher heel-BMD (β [standard error] = 0.0047 [0.0003], P = 1.10 × 10-54). Similarly significant associations were observed for all the fiber subtypes including cereal, fruit (dried and raw), and vegetable (cooked and raw) (all P < .05). A positive association was found in both women and men but more marked among men except for dietary fiber in cooked vegetables (all Pinteraction < .05). A protective association was found between dietary fiber intake and hip fracture (hazard ratio, 95% confidence interval: 0.94, 0.89-0.99; P = 3.0 × 10-2). In addition, the association between dietary fiber and heel BMD was modified by genetically determined SCFA propionate production (Pinteraction = 5.1 × 10-3). The protective association between dietary fiber and heel BMD was more pronounced among participants with lower genetically determined propionate production.

Conclusions: Our results indicate that greater intakes of total dietary fiber and subtypes from various food sources are associated with higher heel-BMD. Participants with lower genetically determined propionate production may benefit more from taking more dietary fiber.

Keywords: bone mineral density; dietary fiber; short-chain fatty acids.

Figure 1.

Effect of SCFA PGS on the association of dietary fiber (1 SD) with heel-BMD. Values were expressed as adjusted least square means ± SE for heel-BMD. P values were adjusted for age, sex, the Townsend Deprivation Index, physical activity (MET-minutes/week), smoking status (never, previous, current), alcohol intake (never, previous, current), body mass index, dietary calcium intake, dietary vitamin D intake, and total energy intake. T1, T2, and T3 refer to tertiles of SCFA PGS. Low, average and high indicate different levels of dietary fiber intake. We used the raw value of the heel-BMD.

Figure 2.

Association of dietary fiber intake (1 SD) and bone health stratified by potential confounders. Multivariable model was mutually adjusted for age, sex, the Townsend Deprivation Index, physical activity (MET-minutes/week), smoking status (never, previous, current), drinking status (never, previous, current), BMI, dietary calcium intake, dietary vitamin D intake, and total energy intake.