ABSTRACT
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 B12, 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/m2, completed an eight-week low energy diet (LED). Serum concentration of folate, retinol, B12, 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 B12, 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 B12 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 B12 and D. Baseline adiposity was inversely associated with folate and retinol, and positively associated with markers of inflammation. TRIAL REGISTRATION: Ethical Committee of Copenhagen as no. H-4-2013-135, NCT01561131.
ABSTRACT
BACKGROUND: Potatoes have been related to increased risks of obesity, type 2 diabetes (T2D), and cardiovascular disease (CVD) mainly because of their high glycemic index. OBJECTIVE: We conducted a systematic review to evaluate the relation between intake of potatoes and risks of obesity, T2D, and CVD in apparently healthy adults. DESIGN: MEDLINE, Embase, the Web of Science, and the Cochrane Central Register of Controlled Trials were searched for intervention and prospective observational studies that investigated adults without any known illnesses at baseline, recorded intake of potatoes, and measured adiposity (body weight, body mass index, or waist circumference), cases of T2D, cases of cardiovascular events, or risk markers thereof. RESULTS: In total, 13 studies were deemed eligible; 5 studies were related to obesity, 7 studies were related to T2D, and one study was related to CVD. Only observational studies were identified; there were 3 studies with moderate, 9 studies with serious, and one study with critical risk of bias. The association between potatoes (not including french fries) and adiposity was neutral in 2 studies and was positive in 2 studies. French fries were positively associated with adiposity in 3 of 3 studies. For T2D, 2 studies showed a positive association, whereas 5 studies showed no or a negative association with intake of potatoes and T2D. French fries were positively associated with T2D in 3 of 3 studies that distinguished this relation. For CVD, no association was observed. CONCLUSIONS: The identified studies do not provide convincing evidence to suggest an association between intake of potatoes and risks of obesity, T2D, or CVD. French fries may be associated with increased risks of obesity and T2D although confounding may be present. In this systematic review, only observational studies were identified. These findings underline the need for long-term randomized controlled trials. This trial was registered at the PROSPERO International prospective register of systematic reviews (www.crd.york.ac.uk/PROSPERO/) as CRD42015026491.