Immune System Support

Detailed Nutrition Information

Vitamin C

Vitamin C behaves as an antioxidant by scavenging Reactive Oxidative Species (ROS) and works with powerful antioxidant enzymes in the body and with vitamins (e.g. glutathione, vitamin E).^2-4 Vitamin C is particularly important to the immune system as it stimulates the production and function of white blood cells and protects cells against ROS that are generated from activation of white blood cells as a result of infection and inflammatory stress.^3-4

Histamine is a compound released by cells in response to allergic and inflammatory reactions. It’s involved in the presentation of symptoms such as nasal stuffiness, runny nose, teary eyes, and coughing. Vitamin C is thought to have an anti-histamine effect,⁵ which could translate to beneficial effects on cold symptoms.^4,6

Results from some studies show that immune functions improve with increased vitamin C intake, while other studies show no effect. The inconsistency may be due to the use of adequately nourished study participants, or because leukocytes saturate with vitamin C at a lower intake than is required to saturate plasma (~100 mg/day).⁴

In a Cochrane review and meta-analysis combining 29 studies,⁷ prophylactic vitamin C supplementation reduced the incidence of colds by 52% in participants undergoing heavy physical stress (e.g., marathon runners, soldiers in subarctic conditions, skiers), while the effect was not significant in the pooled general community trials (RR 0.97 (0.94 to 1.00). Vitamin C supplements also reduced cold duration by 14% in children and 8% in adults, and reduced cold severity in 31 comparisons of 9,745 cold episodes. However, therapeutic trials were inconsistent in these effects. Participants in these studies were taking vitamin C supplements at doses of at least 200 mg/day, with many studies using doses of 1,000 mg/day and higher. Although the levels are significantly greater than the vitamin C amount found in an 8-ounce glass of OJ, these studies help support the importance of vitamin C in immune function.

Vitamin D

Vitamin D strongly modulates the immune system. Many immune cells express vitamin D–activating enzymes allowing them to convert vitamin D precursors to the active form of vitamin D.⁸  This promotes antibacterial responses to pathogens by modulating CD4+ T-cell functions and allows epithelial cells to mount an antibacterial response.⁸

Multiple studies have found associations between low vitamin D and increased risk of infections, including influenza and other respiratory infections and sepsis.⁸ Several meta-analyses have shown mixed results regarding the effectiveness of vitamin D supplementation and improved resistance to respiratory infection. However, many other studies showed positive benefits of vitamin D on respiratory infection, particularly in people with low vitamin D status.⁸

Fortified orange juice varieties often provide vitamin D along with calcium needed for strong bones.

Bioactive Plant Compounds

Many carotenoids found in orange juice, including beta-carotene, alpha-carotene and beta-cryptoxanthin, can form vitamin A in the body which is important for immune function.⁹ Vitamin A is necessary for epithelial cell health, gene expression and immune function.¹⁰ Carotenoids have shown to have antioxidant properties and help reduce inflammation, as well as aid in the immune system.^9,10 Hundreds of studies have shown carotenoids from foods (found in high amounts in fruits and vegetables) to be associated with lower risk of many diseases including macular degeneration, cardiovascular disease and many cancers including of the prostate, breast, cervix and lung.^9,11

Research supports the role of flavonoids in the immune system. In human clinical studies, hesperidin in orange juice exerted positive changes in antioxidant enzymes, altered white blood cell gene expression to anti-inflammatory profiles, and lowered oxidative stress biomarkers that protect against DNA damage and lipid peroxidation.^12,13 A systematic review of randomized controlled trials testing flavonoids’ effects on the respiratory and immune system function found that among those who consumed flavonoids, there was a 33% decrease in upper respiratory tract infections in comparison to those who did not consume flavonoids.¹⁴

The flavonoid hesperidin is highly concentrated in citrus and rarely found in other foods,¹⁵ making orange juice a unique source.

Consider including nutrient-rich Florida Orange Juice in your daily diet. Working to maintain a healthier immune system is also a great way to help you get through cold and flu season. Florida Orange Juice may also help keep you hydrated when you’re on your way to feeling better.