Effect of low energy diet for eight weeks to adults with overweight or obesity on folate, retinol, vitamin B12, D and E status and the degree of inflammation: a post hoc analysis of a randomized intervention trial

Background: Obesity is associated with vitamin insufficiency and low grade inflammation. The purpose of this study was to investigate the effect of weight loss on folate, retinol, vitamin B-12, D and E status and the degree of inflammation. Methods: Out of 110, 85 individuals (75% women) aged 39 +/- 11 years with a mean +/- SD BMI of 33 +/- 4 kg/m(2), completed an eight-week low energy diet (LED). Serum concentration of folate, retinol, B-12, D and E and C-reactive protein and homocysteine (Hcy) were measured at baseline and at end of the LED. Results: At baseline, 8% of the participants were deficient in folate, 13% in vitamin B-12, 2% in retinol, 28% in vitamin D (72% were insufficient in vitamin D), and none were deficient in vitamin E. At baseline, BMI was inversely associated with retinol (P < 0.05) as was total and abdominal fat percentage with folate (P < 0.05); further BMI and measures of adiposity were positively associated with CRP (P < 0.01) and Hcy (P < 0.05). Homocysteine was inversely associated with all vitamins but retinol (P < 0.001). After the LED, the participants lost a mean [95% confidence intervals] of 12.3 [-13.1,-11.6] kg. The serum concentration of folate, vitamin B-12 and D were increased (P < 0.001) after the LED whereas the concentration of retinol and vitamin E were reduced (P < 0.001). Conclusion: Eight-weeks LED resulted in 13% weight loss and an increase in the serum concentrations of folate, vitamin B-12 and D. Baseline adiposity was inversely associated with folate and retinol, and positively associated with markers of inflammation.