Orange juice is often demonized for being high in sugar, but it’s far more than that. A humble glass of orange juice is an incredible source of cancer-fighting nutrients, especially certain unique polyphenols. Naringenin and naringin are the main bioactive polyphenols found in citrus fruits, and their effects range from lowering inflammation to increasing the metabolic rate, to preventing cancer.
Numerous studies have demonstrated that naringenin has anti-inflammatory, anti-infective, antioxidant, anticancer, antimutagenic, antifibrotic, neuroprotective, antidiabetic, DNA protective, liver protective, hypolipidaemic, antidepressant, antihypertension, antiproliferative, antispasmodic, choleretic, antiatherosclerotic, and expectorant effects with low toxicity and widespread availability.
Naringenin and naringin have been shown to inhibit cell proliferation, induce apoptosis, suppress cytokine and growth factor production, arrest the cancer cell cycle, and promote autophagy. They modulate vascular and metabolic pathways by targeting enzymes such as adenosine deaminase (involved in purine metabolism) and cyclic nucleotide phosphodiesterases. It inhibits COX-1, a key enzyme involved in colorectal cancer cell progression.
In-vitro studies have demonstrated that naringenin has cytotoxic and growth-inhibitory effects on a variety of cancer cell lines, including breast, stomach, liver, cervical, pancreatic, colon, and leukemia. It helps to protect against DNA damage and inhibits cancer cell proliferation by blocking the synthesis of polyamines, (molecules essential for the regulation of protein, DNA, and RNA synthesis.) It also disrupts the DNA-protein interactions in cancer cells, which are crucial for maintaining normal cellular functions.
Naringenin causes cell cycle arrest in cancer cells by inhibiting cyclin and cyclin-dependent kinase (CDK). It increases caspase, cytochrome c, and BAX (a major promoter of cell death), and the downregulation of BCL2 in mitochondria. By decreasing vascular endothelial growth factor and downregulating the TGF-pathway, it decreases the metastasis and invasion of cancer.
Naringenin and metabolism.
Naringenin is not only a powerful tool against cancer, but is also extremely beneficial for improving metabolism. Researchers are investigating the potential of naringenin to improve metabolic dysregulation. A number of studies have shown that naringenin has lipid-lowering, insulin sensitizing, antihypertensive, and anti-inflammatory properties, all contributing to its beneficial effects on metabolism.
Naringenin increases the body’s oxygen consumption rate, gene expression of uncoupling protein 1, (UCP1) glucose transporter type 4, and carnitine palmitoyltransferase 1β, (CPT1β) and activates PPARα and PPARγ, all of which increase the metabolic rate.
In animal models, a supplement of citrus flavonoids, including naringenin, prevents hepatic steatosis, dyslipidemia, and increases insulin sensitivity through the inhibition of hepatic fatty acid synthesis. Recent studies have shown that naringenin reduces diet-induces weight gain while improving glucose and lipid metabolism. When mice were fed a high-fat obesogenic diet supplemented with naringenin, they demonstrated an increase in energy expenditure and activation of brown fat. (PMID:3167063)
Naringenin and other flavonoids have been shown to blunt the inflammatory response in metabolically important tissues including the liver, adipose tissue, kidneys, and aorta.
Food sources of naringenin
Including foods rich in these flavonoids is clearly one of the best things that you can do to improve your health and prevent cancer. Orange juice is not the only source of these protective flavonoids, though fresh orange juice is one of the richest and most concentrated sources. Other sources include whole oranges, grapefruit, and grapefruit juice, bergamots, tart cherries, tomatoes, lemons, limes, rosemary, coca, and marmalade. Making drinks and foods with citrus peels can be another way to include these beneficial compounds in the diet.