Natural Strategies for Flu Prevention

In the United States, the death rate from flu and its complications varies. In some years, relatively few die (3,000). In other years, it can be much higher (up to 49,000 or more annual deaths). The CDC calculated that up to 575,000 people may have died from H1N1 swine flu in 2009 in the USA. As of November 2025,  the CDC has stated a new mutated version of the flu virus (subclade K) has emerged. So, this year’s vaccine is not as effective in preventing the flu.

Not 100% Effective!

You hear it every fall before the flu season begins. The typical medical advice is to wash your hands frequently, avoid crowds, and get your flu vaccine. Because flu viruses mutate often, it is advisable to get one’s annual flu shot. Once vaccinated, it takes about two weeks for antibodies to develop in the body and provide protection against influenza virus infection. Flu vaccination–even of moderate efficacy–can also significantly reduce the risk of more serious flu outcomes, like hospitalizations and deaths.

Flu vaccines are helpful but not foolproof. Here is the point that the media often miss: flu vaccines are not 100% effective. They may be only 50 to 79 % effective in blocking the infection. For example, during the 2012-2013 flu season, the flu vaccine’s effectiveness was estimated to be just 56% across all age groups reviewed by the CDC. In individuals aged 65 or older, the flu vaccine’s effectiveness for that particular season was only 9%. Flu vaccines are the most effective in healthy, young adults.¹

The CDC enumerates, “How well the flu vaccine works can vary widely from season to season. The vaccine’s effectiveness can also vary depending on who is getting vaccinated. At least two factors play an important role in determining the likelihood that the vaccine will protect a person from full illness: 1) characteristics of the person being vaccinated, such as their age and health, and 2) the similarity or “match” between the flu viruses that the vaccine is designed to protect against and the flu viruses spreading in the community.”² Obesity, chronic or acute stress, perceived stress, loneliness, and social isolation reduce antibody response to the flu vaccine.

Flu Defenses Simplified

To strengthen your defense against flu viruses, you need more protection—regardless of your vaccination status. This article will explain simple lifestyle measures that support two key immune cells: killer T-lymphocytes and natural killer cells (NK cells), which actively destroy viruses and cancer cells. Memory B- and T-lymphocytes enable a faster immune response after past exposure to the virus. Antibodies play an important role as well.

Cultivate a Positive Attitude

Replace negative thoughts with positive interventions. Major depression reduces NK cells’ effectiveness. A persistent negative outlook erodes both the ability of the NK cells and killer T-lymphocytes to destroy viruses and cancer cells. The emotions and reactive thinking common in depression—helplessness, loneliness, hopelessness, lack of social support, and unhealthy suppression of these feelings—not only depress the mind but also the immune system.

Some Stresses Might Help!

Chronic and acute stresses decrease the number and function of natural killer cells. Stress reduces their ability to make interferon, a chemical that substantially decreases viral replication. However, problem-solving techniques and coping skills improve NK activity in stressed individuals. When individuals, for example, are exposed to a big stressor (i.e. taking a medical school exam), if they have high emotional stability and low anxiety,  stress actually improves NK cell activity.³ On the other hand, the same stress can result in a significant decline in NK cells if the individual possesses high anxiety and low emotional stability.  Fortunately, realistic optimism, self-confidence, trust, and faith improve the natural killer cells’ job performance.⁴ When you have been exposed to a virus or your immune system is down, sip some immune-boosting tea and take time to count your blessings.

One caveat here: since chronic stress, acute stress, or even perceived stress reduces the antibody response from the flu vaccine, if you are going to get a flu shot, don’t get it until you are rested and more relaxed.

Vitamin D Combats Influenza

Before the flu season begins, find out your vitamin D status. A study involving 18,883 participants, 12 years and older, found that people with the lowest blood level of vitamin D reported having significantly more recent colds or flu. The analysis adjusted for demographics and clinical factors (season, body mass index, smoking history, asthma, and chronic obstructive pulmonary disease).⁵ Vitamin D helps to activate your inactive immune responses. Your body produces natural antibiotic-like compounds called antimicrobial peptides in the white blood cells. Bioactive vitamin D dramatically increases the activity of these antimicrobial compounds found in white blood cells and epithelial cells of the respiratory tract.⁶

Unfortunately, nutritional epidemiologists estimate that as many as 50% of North Americans and Europeans have an insufficient amount of vitamin D. To solve this problem, get at least 20 minutes of sunlight a day and consider taking a vitamin D supplement, especially if you are indoors most of the day, are elderly, or have dark skin, as these factors substantially increase your risk for vitamin D deficiency.

Moderate Exercise Helps

Hong Kong researchers discovered that individuals who never or seldom exercise increased their risk of dying from influenza by 5½ to 8 times. In contrast, those who exercised frequently decreased their risk by 4 to nearly 6½ times.⁷  Moderate exercise also helps to slow down the aging of the immune system. Cardiovascular exercise significantly improves the efficacy of the flu vaccine in sedentary, elderly individuals even 24 weeks after the shot is given.⁸ Consistent moderate and vigorous exercise has been linked to a 31% reduction in communicable diseases and a 37% decrease in mortality rate from infectious disease.⁹

Exhaustive Exercise Increases the Risk

Strenuous, exhaustive exercise, however, decreases the number of natural killers and T-lymphocytes. Their activity is depressed for several days.¹⁰ Heavy exertion increases an athlete’s risk of upper respiratory tract infection (URTI) because of negative changes in immune function and elevation of the stress hormones, epinephrine and cortisol.¹¹

Practice Temperance

Temperance is abstinence from all injurious agents and harmful habits, and the moderate use of all good substances and activities. Alcohol suppresses natural killer cell activity.

Partial sleep deprivation temporarily reduces natural killer cell activity. Even a modest sleep deprivation for part of the night can reduce the killing ability of the natural killer cells by almost 30%¹² and promote inflammation. Sleep deprivation can also reduce the effectiveness of flu vaccines.

Nutritional Strategies

Win While You Lose!

Obesity promotes dysfunction in the immune system.  In a controlled study, obese rats have an eight times greater mortality rate from influenza than lean rats.¹³  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.¹⁴   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.¹⁵. Wise calorie restriction slows down the aging of T-lymphocytes and improves their efficiency.  Another caveat here: Because very rapid weight loss can adversely impact natural killer cells, it is usually better to lose weight gradually and steadily.

Avoid the Western-Type Diet

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 natural killer cells.^16,17

To reduce your risk of influenza, avoid junk foods and avoid extreme restriction of dietary fats. Sugar is an immunosuppressant. Essential fatty acids—especially linoleic and omega-3s—are necessary from your diet to control inflammation when your body is fighting the flu. It is extremely difficult, if not impossible, to obtain sufficient linoleic and omega-3s if your fat intake is less than 15% of total calories. Chia seeds, flaxseeds, walnuts, whole organic soybeans, and leafy greens provide good amounts of omega-3 fats.

Antioxidant Boost

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 time of influenza virus infection. If you are taking a little extra vitamin C, don’t forget vitamin E as well. Studies show that vitamin E-induced enhancement of immune functions was associated with significant improvement in resistance to influenza infection in aged mice. There also was a reduced risk of acquiring upper respiratory infections in nursing home residents.¹⁸, ¹⁹

Both antioxidant vitamins and antioxidant phytochemicals help to inhibit the proliferation of influenza viruses and reduce flu’s severe complications.²⁰ 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, kale, broccoli, and cherry tomatoes are 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 one antioxidant vitamin with marginal intakes of another actually creates more free radicals in the body; a condition we don’t want.

Vegetarians, Take Note

The Atherosclerosis Risk in Communities (ARIC) Study showed that healthy plant-based diets are linked to lower hospitalizations from respiratory infections.²¹ In this study, healthy plant-food diets included considerable whole grains, fruits, vegetables, nuts, and legumes.

Additionally, Plant-based diets have been associated with a lower risk and severity of COVID-19.^{22  23  24}

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.  Legumes and nuts have a considerable amount of zinc. One serving of chickpeas has 1.5 milligrams of zinc. A half-cup of oats provides 1.5 milligrams of zinc. A 4-ounce serving has 1.8 milligrams of zinc.

A vegetarian diet increases the risk for vitamin B-12 and vitamin D deficiency if not carefully planned. Both vitamins are essential to the proper function of the immune system.  Wise supplementation is needed.

Juicing

Freshly made 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,  certain fruit juices increase the blood glucose so quickly that they suppress the actions 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 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 the sudden surge of blood sugar like fruit juices do.

Water: Another Biologic Hero

In flu prevention the use of water should be emphasized. Drink at least 8 glasses of water, including herb tea, every day. Adequate hydration is essential for the immune system.

If you do not have circulatory or other serious medical problems, try a contrast shower. Alternate a hot spray for 1 ½ minutes with a cold spray for 20 seconds. Do this hot and cold exchange three times. This stimulates the circulation of the immune cells throughout your blood. An individual with circulatory or neurological conditions should consult with their doctors first before doing any hydrotherapy. Be sure to rest after this treatment. A hot foot bath is a wonderful immune enhancer if you know you have been exposed to the flu virus or your immune system is weak.

Helpful Herbs

Garlic

Raw crushed garlic provides several organosulfur compounds (allicin, diallyltrisulfide, and ajoene) that impart antiviral activities and boost immunity. Garlic has potent activity against many influenza viruses.²⁵ Individuals who have low blood platelets or take blood thinners should not take any medicinal amounts of garlic.

Elderberry

Elderberry has a potent direct antiviral effect against the flu virus. Compounds from elderberries can directly inhibit the flu virus’s entry and replication in human cells and can help strengthen a person’s immune response to the virus. Elderberry inhibits the early stages of infection by blocking essential viral proteins responsible for viral attachment and entry into the host cells. Elderberry also improves communication between the different components of the immune system.²⁶

Black Cumin

Black cumin (Nigella sativa) contains the phytochemical Thymoquinone. This compound helps fight the avian influenza virus. ²⁷

Ginger

The anti-inflammatory herb ginger may help. Test-tube research suggests that ginger extract has antiviral effects against avian influenza.²⁸ Compounds in ginger, such as gingerols and zingerone, have inhibited viral replication and prevented viruses from entering host cells.²⁹

Caveats:

Drugs and herbs can produce adverse effects if taken together. Consult with your pharmacist to make sure you can take herbs with your medicines. Consult your healthcare provider to ensure safe usage if you decide to supplement with extracts, tinctures, or other herbal products if you have a significant medical condition.

Conclusions:

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.

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1. Vaccine Effectiveness for 2012-2013/Seasonal Influenza (flu), www.cdc.gov./flu/[↩]
2. www.cdc.gov/flu… How Well Does the Flu Vaccine Work?[↩]
3. Borella, P., et al, Emotional stability, anxiety, and natural killer activity under examination. Psychoneuroendocrinology, 24(6):13-17, 1979[↩]
4. Hall, E.J., Bolstering Your Immune System. The Journal of Health and Healing, 23(3):16-19.[↩]
5. Ginde, AA. Association between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey. Arch Intern Med. 2009; 169(4):384-390[↩]
6. Cannell J.J., et al, Epidemic influenza and vitamin D. Epidemiol Infect, 134(6):1129-40, 2006[↩]
7. Wong C.M., et al, Is exercise protective against influenza-associated mortality? PLoS ONE, 3(5):e2108, 200[↩]
8. Woods, JA. Cardiovascular exercise training extends influenza vaccine seroprotection in sedentary older adults: the immune function intervention trial. J Am Geriatr Society. 2009 Dec. 57(12):2183-9[↩]
9. Chastin S. Effects of Regular Physical Activity on the Immune System, Vaccination and Risk of Community-Acquired Infectious Disease in the General Population: Systematic Review and Meta-Analysis, Systematic Review  51, pages1673–1686 (2021). https://link.springer.com/article/10.1007/s40279-021-01466-1[↩]
10. Shek, P.N., Strenuous exercise and immunological changes; a multiple-time-point analysis of leukocytes subset CD4/CD8 ratio, immunoglobulin production and NK cell response. Int J Sports Med, 16(7):466-67, 1996[↩]
11. Nieman D.C. Exercise and resistance to infections. Cn J Physiol Pharmacol, 76(5):573-80, 1998[↩]
12. Irwin, M., et al, Partial Sleep Deprivation Reduces Natural Killer Cell Activity in Humans, www.psychosomaticmedicine.org/cgi/reprint/56/6/493.pdf[↩]
13. 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[↩]
14. Karlsson, EA, Diet-induced obesity impairs the T cell memory response to influenza virus infection. J Immunol. 2010 Mar 15; 184(6):3127-33[↩]
15. Park, HL. Obesity-induced chronic inflammation is associated with the reduced efficacy of influenza vaccine. Hum Vaccin Immunother. 2014 Mar 10; 10(5[↩]
16. Kelley, D.S., Dietary fat and human immune response. Inform.7:852-58, 1996[↩]
17. Blakenship, J., How much fat do we need? Journal of Health and Healing, 20(1):8-18[↩]
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[↩]
19. 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.[↩]
20. Unhide, N., Antioxidant therapy as a potential approach to severe influenza-associated complications, Molecules. 2011 Feb 28;16(3):2032-52[↩]
21. Kendrick KN, Kim H, Rebholz CM, Selvin E, Steffen LM, Juraschek SP. Plant-Based Diets and Risk of Hospitalization  with Respiratory Infection: Results from the Atherosclerosis Risk in Communities (ARIC) Study. Nutrients. 2023 Oct 5;15(19):4265. https://pmc.ncbi.nlm.nih.gov/articles/PMC10574784/ [↩]
22. Merino J., J et al. Diet quality and risk and severity of COVID-19: A prospective cohort study. Gut. 2021;70:2096–2104 [↩]
23. Kim H., et al. Plant-based diets, pescatarian diets and COVID-19 severity: A population-based case-control study in six countries. BMJ Nutr. Prev. Health. 2021;4:257–266.  https://pmc.ncbi.nlm.nih.gov/articles/PMC8219480/ [↩]
24. Acosta-Navarro JC, et al. Vegetarian and plant-based diets associated with lower incidence of COVID-19. BMJ Nutr Prev Health. 2024 Jan 9;7(1):4-13. https://pmc.ncbi.nlm.nih.gov/articles/PMC11221288/ [↩]
25. Meng Y., Lu D., Guo N., Zhang L., Zhou G. Anti-HCMV effect of garlic components. Virol. Sin. 1993;8:147–150.[↩]
26. University of Sydney. “Elderberry compounds could help minimize flu symptoms, study suggests.” ScienceDaily. ScienceDaily, 23 April 2019. <www.sciencedaily.com/releases/2019/04/190423133644.htm>.[↩]
27. Rahman, Md Mahbubur, et al. “Traditional foods with their constituents’ antiviral and immune system modulating properties.” Heliyon vol. 7,1 (2021): e05957. doi:10.1016/j.heliyon.2021.e05957[↩]
28. Rasool A. Anti-avian influenza virus H9N2 activity of aqueous extracts of Zingiber Officinalis (Ginger) and Allium sativum (Garlic) in chick embryos. Pak J Pharm Sci. 2017 Jul;30(4):1341-1344.[↩]
29. Arora, Rajesh et al. “Potential of Complementary and Alternative Medicine in Preventive Management of Novel H1N1 Flu (Swine Flu) Pandemic: Thwarting Potential Disasters in the Bud.” Evidence-based complementary and alternative medicine: eCAM vol. 2011 (2011): 586506. doi:10.1155/2011/586506[↩]