Circulating fatty acids (FA) are associated with a multitude of chronic diseases. However, a major gap in establishing such relationships is the lack of accepted fatty acid reference ranges representing healthy individuals. Data on validated FA reference ranges would provide a better understanding of study baseline measures and aid in the evaluation and interpretation of pharmaceutical or dietary interventions. Reference ranges for plasma FA levels have been reported in a few small studies and on a limited number of FA. Therefore, we determined the average and percentiles of a broad set of 61 FA (C14 - C24:1) from plasma total lipids from an ethnically diverse population of healthy young Canadian males and females (Total n = 826). Plasma concentrations of some of the major FA ranged from 0.3 to 4.1 mmol/L for palmitic acid, 0.1 to 1.0 mmol/L for stearic acid, 0.03 to 3.2 mmol/L for oleic acid, 0.2 to 5.0 mmol/L for linoleic acid (LA), 12.0 to 186.9 μmol/L for α-linolenic acid, and 7.2 to 237.5 μmol/L for docosahexaenoic acid (DHA). Males had significantly higher plasma concentrations of γ-linolenic acid (GLA) and n-3 docosapentaenoic acid and lower concentrations of palmitoleic acid, LA and DHA than females. Comparison of FA concentrations between Caucasians, East Asians and South Asians revealed that South Asians had significantly lower levels of palmitoleic acid (p < 0.01) and oleic acid (p = 0.01) while East Asians had lower levels of GLA (p = 0.02) and dihomo-γ-linolenic acid (p = 0.03). Overall, these data provide a comprehensive set of quantitative values that profiles a small cohort of Canadians which highlights the utility of establishing validated FA reference ranges that may be used to understand how deficient, suboptimal, or excess amounts of a given FA may be associated with chronic disease.

Proponents of consumer genetic tests claim that the information can positively impact health behaviors and aid in chronic disease prevention. However, the effects of disclosing genetic information on dietary intake behavior are not clear. A double-blinded, parallel group, 2∶1 online randomized controlled trial was conducted to determine the short- and long-term effects of disclosing nutrition-related genetic information for personalized nutrition on dietary intakes of caffeine, vitamin C, added sugars, and sodium. Participants were healthy men and women aged 20–35 years (n = 138). The intervention group (n = 92) received personalized DNA-based dietary advice for 12-months and the control group (n = 46) received general dietary recommendations with no genetic information for 12-months. Food frequency questionnaires were collected at baseline and 3- and 12-months after the intervention to assess dietary intakes. General linear models were used to compare changes in intakes between those receiving general dietary advice and those receiving DNA-based dietary advice. Compared to the control group, no significant changes to dietary intakes of the nutrients were observed at 3-months. At 12-months, participants in the intervention group who possessed a risk version of the ACE gene, and were advised to limit their sodium intake, significantly reduced their sodium intake (mg/day) compared to the control group (−287.3±114.1 vs. 129.8±118.2, p = 0.008). Those who had the non-risk version of ACE did not significantly change their sodium intake compared to the control group (12-months: −244.2±150.2, p = 0.11). Among those with the risk version of the ACE gene, the proportion who met the targeted recommendation of 1500 mg/day increased from 19% at baseline to 34% after 12 months (p = 0.06). These findings demonstrate that disclosing genetic information for personalized nutrition results in greater changes in intake for some dietary components compared to general population-based dietary advice. ClinicalTrials.gov NCT01353014

The objective of this study was to determine whether single nucleotide polymorphisms (SNPs) in the SCNN1A (3), SCNN1B (12), SCNN1G (6), and TRPV1 (10) genes affect salt taste perception. Participants were men (n = 28) and women (n = 67) from the Toronto Nutrigenomics and Health study aged 21–31 years. Taste thresholds were determined using a 3-alternative forced-choice staircase model with solutions ranging from 9×10⁻⁶ to 0.5mol/L. Suprathreshold taste sensitivity to 0.01–1.0mol/L salt solutions was assessed using general labeled magnitude scales. None of the SNPs in the SCNN1A and SCNN1G genes were significantly associated with either outcome. In the SCNN1B gene, 2 SNPs in intronic regions of the gene modified suprathreshold taste sensitivity (mean iAUC ± SE). Those homozygous for the A allele of the rs239345 (A>T) polymorphism and the T allele of the rs3785368 (C>T) polymorphism perceived salt solutions less intensely than carriers of the T or C alleles, respectively (rs239345: 70.82±12.16 vs. 96.95±3.75, P = 0.02; rs3785368: 57.43±19.85 vs. 95.57±3.66, P = 0.03) In the TRPV1 gene, the rs8065080 (C>T, Val585Ile) polymorphism modified suprathreshold taste sensitivity where carriers of the T allele were significantly more sensitive to salt solutions than the CC genotype (98.3±3.8 vs. 74.1±8.3, P = 0.008). Our findings show that variation in the TRPV1 and the SCNN1B genes may modify salt taste perception in humans.

Personal genetic information has become increasingly accessible to the public as a result of direct-to-consumer (DTC) genetic tests; however, concerns have been raised over their value and potential risks. We compared the effects of providing genotype-based dietary advice with general recommendations on behavioral outcomes using a randomized controlled study. Participants were men and women from the Toronto Nutrigenomics and Health Study between the ages of 20–35 years (n = 149) who completed a survey to assess their awareness of DTC genetic tests and nutrigenomics, as well as potential motivations for undergoing genetic testing. Participants were then randomized into an intervention (I) or control (C) group and were given either genotype-based personalized dietary advice or general dietary advice, respectively. A second survey was administered to assess the participants’ opinions of the dietary reports they received. A greater proportion of participants in the intervention group agreed that they understood the dietary advice they were given (93% (I) vs. 78% (C); p = 0.009). Participants in the intervention group were more likely to agree that the dietary recommendations they received would be useful when considering their diet (88% (I) vs. 72% (C); p = 0.02) and wanted to know more about the recommendations (95% (I) vs. 76% (C); p < 0.0001). Only 9% of participants in the intervention group reported feeling uneasy about learning their genetic information. These findings suggest that individuals find dietary recommendations based on genetics more understandable and more useful than general dietary advice. Very few feel uneasy about receiving their genetic information that relates to personalized nutrition.

Background/Aims: To determine whether variation in the TAS1R2 gene affects sucrose taste perception and sugar intake. Methods: Participants were men (n = 238) and women (n = 458) aged 20-29 years. A subset (n = 95) with body mass index (BMI) data available completed a sensory analysis study. A food frequency questionnaire assessed dietary intake, and eight polymorphisms were genotyped (rs12033832, rs12137730, rs35874116, rs3935570, rs4920564, rs4920566, rs7513755 and rs9701796). Sucrose taste thresholds were determined by staircase procedure (solutions: 9 × 10-6 to 0.5 mol/l). Suprathreshold sensitivity to 0.01-1.0 mol/l sucrose solutions was assessed using general Labeled Magnitude Scales. Results: A significant genotype-BMI interaction was observed for rs12033832 (G>A) for suprathreshold sensitivity (p = 0.01) and sugar intake (p = 0.003). Among participants with a BMI ≥25, G allele carriers had lower sensitivity ratings (mean incremental area under the taste sensitivity curve ± SE; GG/GA 54.4 ± 4.1 vs. AA 178.5 ± 66.6; p = 0.006), higher thresholds (GG/GA 9.3 ± 1.1 vs. AA 4.4 ± 4.3 mmol/l; p = 0.004) and consumed more sugars (GG/GA 130 ± 4 vs. AA 94 ± 13 g/day; p = 0.009). G allele carriers with a BMI <25 had lower thresholds (GG/GA 8.6 ± 0.5 vs. AA 16.7 ± 5.7 mmol/l; p = 0.02) and consumed less sugars (GG/GA 122 ± 2 vs. AA 145 ± 8 g/day; p = 0.004). Conclusion: The rs12033832 single nucleotide polymorphism in TAS1R2 is associated with sucrose taste and sugar intake, but the effect differs depending on BMI.