Fruits and vegetables have a lot more to offer the immune system than just their vitamins and minerals. The phytonutrients, antioxidants, fibers, oils and acids in fruits and vegetables, which are responsible for their various flavors and colors, are also responsible for their many health, healing and immune- modulating properties. These bioactive compounds are used by the body to directly combat inflammation and infections and support detoxification and immune cell function through a multitude of mechanisms, many of which have yet to be fully understood.
Oranges and Yellows
Due to their vitamin-C content, citrus fruits such as oranges and lemons have been touted as cure-alls for the cold and flu. Although vitamin C is integral to proper immune function, citrus fruits have a lot more to offer than just one vitamin. Research published in the “Journal of Agricultural and Food Chemistry” confirms that over 8,000 flavonoids have been identified with many coming from citrus. Some of the most well-studied flavonoid compounds in citrus, such as quercetin, rutin, hesperidin, apigenin and tangeretin, have all shown some ability to target immune malfunctions such as excessive inflammation and cancer development.
Compounds in cranberry juice have been shown to be beneficial for the prevention and treatment of urinary tract infections while also decreasing the use of antibiotics in the elderly. Goji berries, also known as wolfberries, are red berries from China that have immune-regulating properties as evidenced by a 2009 study from “Journal of Medicinal Food”, which showed daily consumption of goji juice increased immune cells called lymphocytes and antibodies called immunoglobulin G when compared to a placebo. Lycopene is the most potent antioxidant in tomatoes and the same pigment molecule that gives red bell peppers and watermelon their red color . However, there are also many additional compounds in tomatoes and tomato products that can protect the DNA of immune cells from oxidative damage and therefore promote proper immune function.
Blues and Purples
Exercise benefits the skeletal system and the cardiovascular system, but strenuous exercise increases inflammation and oxidative stress in the body, which can put a strain on the immune system. Blueberries are full of potent antioxidants called anthocyanins, which help to counter exercise-induced stresses on the immune system by increasing anti-inflammatory compounds and natural killer cells – immune cells which help fight infections. Purple grapes are also full of similar anthocyanin antioxidants, and regular consumption of 100-percent grape juice can increase antioxidant status as well as circulating levels of immune cells called gamma delta T cells in the intestines and lungs. The importance of gamma delta T cells is just starting to be fully appreciated as experiments have shown that they act both as a first line of defense against certain pathogens and also link the innate and adaptive branches of the immune system.
Greens and Whites
Cancer is one of the ultimate immune disorders as cancerous cells need to evade multiple immune defenses and checkpoints in order to become malignant and spread. Regular consumption of cruciferous vegetable such as broccoli, cabbage and cauliflower have beneficial effects on several types of cancer through their powerful anticarcinogenic agents such as sulforaphane, isothiocyanates and indoles. Leafy green vegetables such as spinach and kale are rich in vitamin A, vitamins C, chlorophyll, antioxidants and essential fatty acids, which have immunostimulatory and immunoprotective effects while the sulfur-rich molecules in garlic known as allyl compounds work on numerous immune pathways by being antibacterial, antifungal, antiviral and anticarcinogenic.
Articles For Your Diet
- American Journal of Clinical Nutrition: Health Effects of Vegetables and Fruit: Assessing Mechanisms of Action in Human Experimental Studies
- Journal of Agricultural and Food Chemistry: Update on Uses and Properties of Citrus Flavonoids: New Findings in Anticancer, Cardiovascular, and Anti-inflammatory Activity
- Clinical Infectious Diseases: Nutritional Strategies to Boost Immunity and Prevent Infection in Elderly Individuals
- Journal of Medicinal Food: Immunomodulatory Effects of a Standardized Lycium barbarum Fruit Juice in Chinese Oder Healthy Human Subjects.
- British Journal of Nutrition: Daily Intake of a Formulated Tomato Drink Affects Carotenoid Plasma and Lymphocyte Concentrations and Improves Cellular Antioxidant Protection
- European Journal of Nutrition: Spinach and Tomato Consumption Increases Lymphocyte DNA Resistance to Oxidative Stress but this is Not Related to Cell Carotenoid Concentrations
- Applied Physiology, Nutrition and Metabolism: Effect of Blueberry Ingestion on Natural Killer Cell Counts, Oxidative Stress, and Inflammation Prior to and After 2.5 h of Running
- Journal of Medicinal Food: Regular Consumption of Concord Grape Juice Benefits Human Immunity.
- The Journal of Nutrition: Grape Consumption Supports Immunity in Animals and Humans.
- Oncology Research: TLR4 Signaling Promotes Immune Escape of Human Colon Cancer Cells by Inducing Immunosuppressive Cytokines and Apoptosis Resistance
- Annals of Oncology: Cruciferous Vegetables and Cancer Risk in a Network of Case-Control Studies.
- Bioscience, Biotechnology and Biochemistry: Immunostimulatory in Vitro and in Vivo Effects of a Water-Soluble Extract from Kale.
- European Journal of Nutrition: Impact of Spinach Consumption on DNA Stability in Peripheral Lymphocytes and on Biochemical Blood Parameters: Results of a Human Intervention Trial.
- Environmental and Molecular Mutagenesis: Biological Properties of Garlic and Garlic-Derived Organosulfur Compounds
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