Examining the relationship between Vitamin A intake and weight management

Introduction: Treatments of retinoic acid, a metabolite of vitamin A (VA) are shown to induce hyperlipidemia in humans and animals, which may influence adiposity. To understand the role of VA in weight management, two studies, one in animals examining effects of VA combined with high-fat diet (HFD) on body mass (BM) gain and the second in humans comparing dietary VA between participants who were overweight/obese and who had and had not lost 10% of body weight by consuming a hypocaloric, low-fat diet, were conducted.

Methods: Male Sprague Dawley rats were fed a HFD containing sufficient VA (HF-VAS) or a HFD deficient in VA (HF-VAD) for eight weeks. BM, liver mass, white adipose mass, brown adipose mass and plasma glucose were measured. The groups were compared with student's t-test. For the second experiment, participants (51.9 ± 8.8 yrs, 35.0 + 4.5 kg/m², 94.7% white, 59.6% female, 100% non-hispanic) in a lifestyle intervention were categorized as successful weight losers (loss of > 10% body weight) or unsuccessful weight losers (loss of < 10% body weight) after 6 months of treatment on a hypocaloric, low-fat diet. Dietary intake, assessed by three, 24-hour dietary recalls was collected at 6 months. Dietary VA was compared between the groups using analysis of covariance.

Results: In the animal study, significant differences were detected in end day BM, liver mass and white adipose mass between the HF-VAS and HFD-VAD groups. No significant difference was detected in dietary VA consumed between participants who had successful 10% weight loss and those who did not have successful weight loss at 6 months.

Conclusion: Results from the animal experiment indicate that VA plays a role in adiposity in subjects consuming an obesogenic diet. No difference was detected in VA intake between subjects who successfully lost 10% weight and those who have not. This indicates dietary VA is not related to successful weight loss on a hypocaloric, low-fat diet. Additional studies are needed to understand the role VA plays in obesity development. Also, further investigation on how VA intake while consuming a hypocaloric low fat diet may affect weight loss is needed.