Dietary variables, correlation between

If this model is selected, one must then decide what variables to use for the ordinate and the abscissa. The parameters must be dose-sensitive, free of confounding variables, easily determined and preferably linear. We have evaluated this approach for estimating the bioavailability of calcium in mechanically deboned meat products (11). Typically, correlations between various bone parameters and dietary calcium are very high (r = 0.943 to 0.999). This is consistent with what others have found for similar parameters (46,47). These correlations are also similar to the those (r = 0.947 to 0.982) between the amount of calcium consumed and calcium retained (11) a good index procedure. 

Table I. Correlation Coefficients Between Dietary Variables...

To ascertain whether dietary food records were inaccurate because of associated mild cognitive deficits, blood levels of these nutrients were measured. Scores on the Halstead-Reitan Category Test were worse in subjects with lower blood levels of ascorbate, riboflavin, Bj2, and folate, while those on the Wexler Memory Test were correlated with ascorbate and Bj2 levels. These findings do not appear to be explained by age variation within the group, since there was no overall correlation between any nutritional variable and age per se. To correct for any effects of educational status and income level, analysis of covariance was performed it did not alter the degree or the statistical significance of the associations between performance on the cognitive tests and blood levels of the vitamins. 

Dietary fat also shows a positive correlation with age-adjusted mortality from cancer at certain other sites in the body, including the colon, rectum and prostate (Carroll Khor, 1975). It should be noted, however, that other dietary variables, such as caloric intake and intake of animal protein, show similar correlations. This simply reflects the fact that fat intake, caloric intake and animal protein intake in different countries each tend to be correlated with one another. One should therefore be wary of assuming that correlations between dietary variables and cancer mortality imply a causative relationship, unless there is other supporting evidence. 

Many studies have focused on the blood phenylalanine level in treated PKU. Factors such as timing of treatment initiation, lifetime level of metabolic control, and current dietary status, all have an impact. In most studies, if treatment is initially delayed past the first 3 months of life, a child performs less well than siblings with PKU who are treated earlier. If metabolic control is variable throughout childhood, the individual tends to have poorer mental processing skills, slower reaction time, diminished achievement, and lower IQ scores. One study has documented IQ loss in early treated adolescents with elevated phenylalanine levels (Beasley et al., 1994). By 18 years of age, 27% have an IQ less than 70. IQ is significantly related to the average phenylalanine control between birth and 14 years of age. The current blood phenylalanine level in an individual with PKU is also correlated with reaction time (Clarke et al., 1987 Schmidt et al., 1994) and is... 

---