Centre for Advanced Sensory Science.
Institute of Physical Activity and Nutrition, School of Exercise and Nutrition Sciences.
Am J Clin Nutr. 2018 May 1;107(5):683-694. doi: 10.1093/ajcn/nqy022.
Individuals with impaired fat taste (FT) sensitivity have reduced satiety responses after consuming fatty foods, leading to increased dietary fat intake. Habitual consumption of dietary fat may modulate sensitivity to FT, with high consumption decreasing sensitivity [increasing fatty acid taste threshold (FATT)] and low consumption increasing sensitivity (decreasing FATT). However, some individuals may be less susceptible to diet-mediated changes in FATT due to variations in gene expression.
The objective of this study was to determine the effect of an 8-wk low-fat or high-fat diet on FATT while maintaining baseline weight (<2.0 kg variation) to assess heritability and to explore the effect of genetics on diet-mediated changes in FATT.
A co-twin randomized controlled trial including 44 pairs (mean ± SD age: 43.7 ± 15.4 y; 34 monozygotic, 10 dizygotic; 33 women, 10 men, 1 gender-discordant) was conducted. Twins within a pair were randomly allocated to an 8-wk low-fat (<20% of energy from fat) or high-fat (>35% of energy from fat) diet. FATT was assessed by a 3-alternate forced choice methodology and transformed to an ordinal scale (FT rank) at baseline and at 4 and 8 wk. Linear mixed models were fit to assess diet effect on FT rank and diet effect modification due to zygosity. A variance components model was fit to calculate baseline heritability.
There was a significant time × diet interaction for FT rank after the 8-wk trial (P < 0.001), with the same conclusions for the subset of participants maintaining baseline weight (low-fat; n = 32; high-fat: n = 35). There was no evidence of zygosity effect modification (interaction of time × diet × zygosity: P = 0.892). Heritability of baseline FT rank was 8%.
There appears to be little to no genetic contribution on heritability of FATT or diet-mediated changes to FATT. Rather, environment, specifically dietary fat intake, is the main influencer of FT sensitivity, regardless of body weight. This trial was registered with the Australian New Zealand Clinical Trials Registry at http://www.anzctr.org.au/ as ACTRN12613000466741.
味觉敏感度受损的个体在食用高脂肪食物后饱腹感反应降低，导致膳食脂肪摄入量增加。习惯性摄入膳食脂肪可能会调节对味觉敏感度的影响，高摄入量会降低敏感度[增加脂肪酸味觉阈值（FATT）]，低摄入量会增加敏感度（降低 FATT）。然而，由于基因表达的差异，一些个体可能对饮食介导的 FATT 变化不太敏感。
本研究的目的是在维持基线体重（<2.0 公斤变化）不变的情况下，确定 8 周低脂肪或高脂肪饮食对 FATT 的影响，以评估遗传率，并探讨遗传因素对饮食介导的 FATT 变化的影响。
一项包括 44 对双胞胎（平均年龄±标准差：43.7±15.4 岁；34 对同卵双胞胎，10 对异卵双胞胎；33 名女性，10 名男性，1 名性别不一致）的双胞胎随机对照试验。每对双胞胎随机分配到 8 周的低脂肪（<20%的能量来自脂肪）或高脂肪（>35%的能量来自脂肪）饮食。通过 3 种交替强迫选择方法评估 FATT，并在基线和 4 周和 8 周时转换为等级量表（FT 等级）。线性混合模型用于评估饮食对 FT 等级的影响以及由于同卵性造成的饮食影响修饰。方差分量模型用于计算基线遗传率。
在 8 周试验后，FT 等级有显著的时间×饮食交互作用（P<0.001），对于维持基线体重的参与者子集（低脂肪组：n=32；高脂肪组：n=35）也有相同的结论。没有证据表明同卵性有影响修饰作用（时间×饮食×同卵性的交互作用：P=0.892）。FT 等级的基线遗传率为 8%。
FATT 的遗传率或饮食对 FATT 的变化的遗传贡献似乎很小或没有。相反，环境，特别是膳食脂肪摄入量，是影响味觉敏感度的主要因素，而与体重无关。本试验在澳大利亚新西兰临床试验注册中心注册，网址为 http://www.anzctr.org.au/，注册号为 ACTRN12613000466741。
