Grapefruit has been used in diets since the 1930’s. There are now a number of scientific research papers providing evidence for grapefruits ability to alter body composition, improve insulin resistance & act as an antioxidant.
How can we take advantage of grapefruit? Grapefruit has a number of nutritional benefits, it is a rich source of Vitamin C (100g serving > 20% RDV), contains the fiber pectin, the pink & red hue contains lycopene & Naringin both antioxidants. A study has shown grapefruit can also help lower cholesterol (1).
Weight loss
A study compared the difference in weight loss between groups when given grapefruit juice, fresh grapefruit or a placebo capsule. After 12 weeks, the fresh grapefruit group had lost 1.6 kg, the grapefruit juice group had lost 1.5 kg and the placebo group had lost 0.3 kg. The fresh grapefruit group lost significantly more weight than the placebo group (P < .05) (2).
– Fresh grapefruit and grapefruit juice showed very similar changes in weight loss between groups. In only drinking the juice the fiber benefits of the fruit are lost.
– The serving size was ½ a grape fruit or 240ml of grapefruit juice.
Insulin response, Angiogenesis & Antioxidant
The same study performed a secondary analysis which found, there was also a significant reduction in 2-hour post-glucose insulin level in the grapefruit group compared with placebo (2). Grapefruit contains the compound ‘Naringin’ which in animal studies has shown:
– Naringin has shown protective effects against cognitive dysfunction and oxidative damage in rats (3).
– Naringin is an inhibitor of vascular endothelial growth factor (VEGF) release, which causes angiogenesis (formation of new blood vessels) (4).
– Naringin reduced diabetes-induced neuropathy in rats (5).
These studies show the potential for grapefruit to have a protective influence on the nervous system (antioxidant). Also the potential to form new blood vessels assisting athletes achieve a more vascular look.
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References:
1. Platt R (2000). “Current concepts in optimum nutrition for cardiovascular disease”. Prev Cardiol 3 (2): 83–7.
2.Ken Fujioka, Frank Greenway, Judy Sheard, and Yu Ying. “The Effects of Grapefruit on Weight and Insulin Resistance: Relationship to the Metabolic Syndrome”. Journal of Medicinal Food. Spring 2006, 9(1): 49-54.
3. Kumar A, Dogra S, Prakash A (2010). “Protective Effect of Naringin, a Citrus Flavonoid, against Colchicine-Induced Cognitive Dysfunction and Oxidative Damage in Rats”. Journal of Medicinal Food 13 (4): 976–84
4. Schindler R, Mentlein R (2006). “Flavonoids and Vitamin E Reduce the Release of the Angiogenic Peptide Vascular Endothelial Growth Factor from Human Tumor Cells”. The Journal of Nutrition 136 (6): 1477–82.
5. Kandhare AD, Raygude KS, Ghosh P, Ghule AE, Bodhankar SL (2012). “Neuroprotective Effect of Naringin by Modulation of Endogenous Biomarkers in Streptozotocin Induced Painful Diabetic Neuropathy”. Fitoterapia 83 (4): 650–9.
