TABLE 2.
Within-pair percentage difference in geometric means of plasma oxidative stress biomarker concentrations per 1-unit within-pair difference in the Mediterranean diet score (MDS)1
| Outcome | Monozygotic ( dizygotic (n = 297)2 |
P for interaction with zygosity | |
|---|---|---|---|
| Within-pair difference (95% CI)3 | P | ||
| % | |||
| Model 14 | |||
| GSH (μmol/L) | −0.6 (−6.5, 5.7) | 0.85 | 0.92 |
| GSSG (μmol/L) | −9.2 (−16.9, −0.7) | 0.03 | 0.78 |
| GSH/GSSG | 9.5 (2.2, 17.4) | 0.01 | 0.77 |
| aEh GSH/GSSG (mV) | 0.8 (−0.1, 1.7) | 0.07 | 0.94 |
| Model 25 | |||
| GSH (μmol/L) | −1.3 (−7.1, 5.0) | 0.68 | 0.76 |
| GSSG (μmol/L) | −10.1 (−17.7, −1.8) | 0.02 | 0.62 |
| GSH/GSSG | 10.1 (2.7, 18.0) | 0.007 | 0.78 |
| aEh GSH/GSSG (mV) | 0.8 (−0.1, 1.7) | 0.09 | 0.77 |
GSH, glutathione; GSSG, glutathione disulfide; GSH/GSSG, ratio of GSH to GSSG; aEh GSH/GSSG, absolute value of redox potential for the GSH/GSSG couple.
Includes 138 twin pairs and 21 unpaired twins.
Values are within-pair percentage differences in geometric means (95% CI) calculated from the β coefficient given a 1-unit within-pair difference in the MDS. A negative within-pair percentage difference indicates that the twin with the higher score has a lower biomarker concentration than his co-twin, whereas a positive value indicates that the twin with the higher score has a higher biomarker concentration. Linear mixed models included the MDS and covariates as fixed effects and the twin pair as a random effect, accounting for clustering within a pair, and allowed for different correlations in monozygotic and dizygotic pairs in the pooled samples.
Controlled for zygosity and nutritional factors, including total energy intake (continuous), egg and potato consumption (continuous), oxidative stress–related nutritional factors [supplements containing fish oil (yes or no), vitamins and minerals (ordinal), magnitude of habitual removal of visible fat on meat (ordinal), frequency of consumption of punches and fruit drinks (ordinal), frequency of consumption of fried food, and types of cooking oils (ordinal)].
Adjusted for the same variables as for model 1 plus age (continuous), education (continuous), marital status (yes or no), current smoking (yes or no), waist-to-hip ratio (continuous), physical activity (continuous), depressive symptom score (continuous), plasma glucose (continuous), systolic blood pressure (continuous), LDL cholesterol (continuous), ratio of HDL cholesterol to triacylglycerols (continuous), and use of statins (yes or no) and aspirin (yes or no).