Wouldn’t it be wonderful if there were a delicious diet that could greatly reduce your risk for getting the flu? Because even though flu vaccines are helpful, they are not 100% effective. For example, the flu vaccine for 2016 seem to reduce flu risk by 23%. Fortunately, most other years, the vaccine has been more effective. In other words, individuals may need to fortify their immune system with additional means. In this blog, we examine the foods that help to optimized the immune system.
A good diet can help reduce your risk for influenza! When the flu season hits, eat a vegetarian diet. Why? A well-balanced, healthful vegetarian diet does improve immunity to viruses by helping to double the activity of natural killer cells (special immune cells that destroy viruses and cancer cells).1 One study of nearly 12,000 adults who adhere to diets high in any plant foods, as well as healthy plant foods, have a lower risk of hospitalization with infections, including respiratory infections.2 Of course, a high sugar plant-based diet with frequent consumption of refined grains, suppresses certain aspects of the immune system and fuels inflammation.
Eat Only Plant-Based Whole Foods!
A fiber-rich diet of whole plant foods also reduces your chances of getting influenza! A high-fiber diet blunts harmful, excessive immune responses in the lungs while boosting antiviral immunity by activating T cells.3 Additionally, soluble fiber transforms the personality of immune cells. They go from being pro-inflammatory, angry cells to anti-inflammatory, healing cells that enable us to recover faster from infection.4 Bring on the apples, oats, and beans. Meat substitutes generally are high in sodium and fat, but very low in fiber. Juices have minimal fiber. Definitely not a winning combination for preventive medicine! Sugar is an immune suppressant of influenza.
The typical western diet suppresses the immune system. A high fat diet slows antibody production and suppresses the immune system in general. When the total fat is decreased from 30% to 25% of the total calories, T and B-lymphocyte activity increases significantly. Reduction of fat intake from 32% to 22% of the total calories can also improve the activity of the natural killer cells.5,6 Extreme restriction of dietary fats reduces immune efficiency and encourages inflammation. When fighting influenza, the body makes plenty of inflammatory chemicals; therefore, essential fatty acids are necessary to prevent this inflammation from getting out of control. It is extremely difficult to get sufficient omega-3 if your fat intake is less than 15% of your total calories.
Enjoy Fresh or Frozen Fruits and Vegetables!
Eating foods rich in antioxidants gives the immune system an extra boost. Vitamin C helps the body’s anti-viral immune responses at the early onset of influenza virus infection. Studies showed that vitamin E-induced enhancement of immune function was associated with significant improvement in resistance to influenza infection in aged mice. These studies also showed a reduced risk of acquiring upper respiratory infections in nursing home residents.7,8 Almonds, peanuts, hazelnuts, spinach, and broccoli are good sources of vitamin E. If you are taking a little extra vitamin C, don’t forget to take vitamin E as well.
Use Garlic, Onions, and Cruciferous Veggies
Both antioxidant vitamins and antioxidant phytochemicals help to inhibit the proliferation of influenza viruses and reduce flu’s severe complications.9 Glutathione, resveratrol, and quercetin are among the anti-viral and anti-influenza phytochemicals. Where can you find these? Garlic, onions, cruciferous vegetables, tomatoes, and avocados are rich in glutathione. Grapes and blueberries contain resveratrol. Onions are very high in quercetin.
Don’t think swallowing a vitamin pill provides all the antioxidants you need. You need healthful plant foods to furnish you with a variety of anti-oxidant and anti-inflammatory phytochemicals. Remember, too much of the one antioxidant vitamin with marginal intakes of the other, actually creates more free radicals in the body, a condition we don’t want.
Enjoy Freshly Made Vegetable Juice
Fresh vegetable and fruit juices provide a variety of antioxidants and anti-inflammatory phytochemicals. It is generally better to use more vegetable juice than fruit juice. If you can tolerate it and are not on blood-thinning drugs, add fresh garlic, as it boosts the immune system. When taken alone, fruit juice ups the blood glucose so quickly that it suppresses the action of neutrophils. Although neutrophils do not seem to protect from viruses, they do destroy bacteria. Because both viral and bacterial pneumonias are possible complications of the influenza, it is best to emphasize freshly made vegetable juice if you want to go that route. Whole fruit, because it is packaged with fiber, does not provide a sudden surge of blood sugar like fruit juices do.
Win While You Lose!
Obesity promotes dysfunction in the immune system. In a controlled study obese rats had an eight times greater mortality rate from influenza than lean rats.10 Obesity also decreases the efficiency of natural killer cells. Diet-induced obesity impairs the ability of the memory-T cells to initiate a swifter immune response to destroy. The function of influenza-specific memory T cells is significantly reduced and ineffective in lungs of obese mice.11 The efficacy of the flu vaccine is much less in obese individuals than in lean persons.
Evidence suggests that inflammatory conditions in obesity may contribute to the suppressed efficacy of influenza vaccination.12 It is good to know that wise calorie restriction slows down the aging of T-lymphocytes and improves their efficiency. Another caveat here: Because very rapid weight loss can adversely affect natural killer cells, it is usually better to lose weight gradually and steadily.
Vegetarians, Take Note!
Zinc is a trace mineral that exerts antioxidant activity and is essential for all immune cells. Zinc deficiency reduces the efficiency of T-lymphocytes. While it is important to have sufficient zinc in your diet, too much zinc can actually inhibit the function of the immune system. How much do you need? About 11 to 15 milligrams a day for an adult. Taking more than 25 mgs a day can have adverse effects. Plant foods are not high in zinc. A half a cup of tofu provides 2 mgs. of zinc, one cup of oatmeal has 2.3mgs. of zinc, one-half cup of most legumes and one-fourth cup of nuts contain approximately 1 mg. of zinc. Vegetarians can be at risk for zinc deficiency if their diet is not carefully balanced to include zinc.
Vegetarians and vegans need to be sure that their vitamin B-12 and vitamin D levels are in a good range. Unless one eats foods fortified with these vitamins or gets them through supplementation, a person eating a vegan or vegetarian diet can develop serious deficiencies. Vitamin B-12 is important for white blood cell production. Vitamin D helps to activate your inactive immune responses. Your body produces natural antibiotic-like compounds called antimicrobial peptides in the white blood cells. Bio-active Vitamin D dramatically increases the activity of these antimicrobial compounds found in white blood cells and epithelial cells of the respiratory tract.
Water: Another Biologic Hero
In flu prevention the use of water should be emphasized. Drink at least eight glasses of water, including herb tea, every day. Adequate hydration is essential for the immune system.
Garlic enhances immune functions and has antibacterial, antifungal, and antiviral activities. Aged garlic improves natural killer activity and is extremely useful for preventing psychologically induced immune damage. Supplementation with an encapsulated aged garlic extract for 90 days has shown a reduction in severity of symptoms, the number of days of illness, and incidences of colds and flu.13 Garlic is a natural blood thinner and can lower high blood pressure, so large amounts of garlic should be avoid by individuals who are taking a blood thinner, have a bleeding disorder, or low blood pressure.
If you have been exposed to the flu virus, try this cocktail: 1 quart of water, 1 peeled garlic clove, and 1 lemon or grapefruit; blend all together and drink. Individuals who are taking blood thinners, have bleeding disorders, or low blood pressure should avoid using garlic medicinally.
Compounds from elderberries can directly inhibit the virus’s entry and replication in human cells, and can help strengthen a person’s immune response to the virus.14 Too many elderberries can produce diarrhea. In vitro studies indicate that curcumin from turmeric has manifested some anti-flu activities.15 It inhibits certain influenza viruses by at least four different mechanisms.16 Additionally, curcumin helps to balance the immune components. Since curcumin is fat-soluble take a little after eating a meal. Thyme is a natural herbal cough medicine. It reduces spasms in the bronchial tubes and improves the clearance of excess mucus in the respiratory tract.
One final caveat here: As important as diet is in flu prevention, no diet—however good—can substitute for sufficient sleep, regular exercise, a peaceful mind, frequent hand washing, and other hygienic practices. In conclusion, proper nutrition, water, good hygiene, exercise, temperance, exposure to sunlight, rest, fresh air, and a positive, trusting attitude, form a chain of optimal health. Your immune system is only as strong as your weakest link.
Works cited: (References below the photo)
Flu vaccine barely working this year, CDC says, Today.com-Jan 1! www.today.com/health/flu-vaccine-barely-working-year-cdc-says-1D80428360
- Malter M. Natural killer cells, vitamins, and other blood components of vegetarian and omnivorous men. Nutr and Cancer. 1989; 12:271-278.
- Kendrick, K., et al. Abstract P214: Plant-based Diets And Risk Of Hospitalization With Respiratory Infection: Results From The Atherosclerosis Risk In Communities (ARIC) Study. Circulation. 2022;145:AP214. https://www.ahajournals.org/doi/10.1161/circ.145.suppl_1.P214
- Cell Press. “A high-fiber diet protects mice against the flu virus.” ScienceDaily. ScienceDaily, 15 May 2018. www.sciencedaily.com/releases/2018/05/180515113805.htm.
- University of Illinois at Urbana-Champaign. “An apple a day? Study shows soluble fiber boosts immune system.” ScienceDaily. ScienceDaily, 17 March 2010. www.sciencedaily.com/releases/2010/03/100302171531.htm.
- Kelley, D.S., Dietary fat and human immune response. Inform.7:852-58, 1996.
- Blankenship, J., How much fat do we need? Journal of Health and Healing, 20(1):8-18.
- Han, S.N., Meydani, S.N., Antioxidants, cytokines, and influenza infection in aged mice and elderly humans. J Infect Dis 182 (Suppl 1):S74-80, 2000.
- Meydani S.N., Han S.N., Wu, D., Vitamin E and immune response in the aged: molecular mechanisms and clinical implications. Immunol Rev. 205:269-84, 2005.
- Unhide, N., Antioxidant therapy as a potential approach to severe influenza-associated complications, Molecules. 2011 Feb 28; 16(3):2032-52.
- Smith, Alexia G., doctorate dissertation: Obesity alters the immune response to the influenza virus infection—a mechanism for immune modulation, University of North Carolina, Chapel Hill, 2007.
- Karlsson, EA, Diet-induced obesity impairs the T cell memory response to influenza virus infection. J Immunol. 2010 Mar 15; 184(6):3127-33.
- Park, HL. Obesity-induced chronic inflammation is associated with the reduced efficacy of influenza vaccine. Hum Vaccin Immunother. 2014 Mar 10; 10(5).
- Haider Abdul-Lateef Mousa. Prevention and Treatment of Influenza, Influenza-Like Illness, and Common Cold by Herbal, Complementary, and Natural Therapies. J Evid Based Complementary Altern Med. 2017 Jan; 22(1): 166–174.
- Golnoosh Torabian, Peter Valtchev, Qayyum Adil, Fariba Dehghani. Anti-influenza activity of elderberry (Sambucus nigra). Journal of Functional Foods, 2019; 54: 353. DOI: 10.1016/j.jff.2019.01.031
- Chen Da-Yaun. Curcumin inhibits influenza virus infection and haemagglutination activity. Food Chemistry. Volume 119, Issue 4, 15 April 2010, Pages 1346-1351. www.sciencedirect.com/science/article/pii/S0308814609010553
- Kim M., et al., Elucidating the Effects of Curcumin against Influenza Using In Silico and In Vitro Approaches. Pharmaceuticals (Basel, Switzerland), 14(9), 880. https://doi.org/10.3390/ph14090880