Life Extension Magazine®

Wife looking after husband that is sick from a virus

Prevent Viruses from Taking Hold and Reduce Recovery Time

During post-flu recovery older adults are at increased risk for pneumonia, bacterial infections, and death. French oak wood extract has been shown to markedly speed post-flu recovery, reduces fatigue, and improves sleep patterns.

Scientifically reviewed by: Dr. Cristina Matthewman, Ph.D., Neuroscience, in August 2023. Written by: Stephanie Riser.

According to Centers for Disease Control and Prevention during the 2017-2018 flu season, an estimated of 810,000 people were hospitalized due to influenza and close to 61,000 died from influenza-related complications. 1

The annual flu is a threat to the entire population. People over 65 are especially vulnerable because of age-related weakening of their immune systems.

Contracting a flu virus further weakens immune functions,2 and may lead to serious complications like bacterial pneumonia or sepsis in these vulnerable populations.

The best ways of protecting against the flu is prevention with vaccination and to attack it with an arsenal of anti-viral compounds that can alleviate symptoms and further complications.

Tamiflu® is nearly a 20-year old drug that is effective if taken within 24-48 hours after onset of flu symptoms. Flu viruses, however, can mutate and become resistant to antiviral drugs like Tamiflu.

What you need to know

  • Influenza can have a devastating impact on older adults.
  • Adults over 65 are at an increased risk of suffering from flu complications such as pneumonia, sinus problems, organ failure, and even death.
  • French oak wood extract has been shown to speed recovery from the flu.
  • In a preliminary study, the addition of oak wood extract to standard management improved fatigue and recovery rates for weakness, sleep, concentration, and attention.
  • Speeding recovery helps reduce the likelihood of suffering from potentially deadly complications.

A new antiviral drug called Xofluza™ has been recently FDA-approved. Xofluza works via a different mechanism than Tamiflu.4 What's critical with either drug is having it available as soon as flu symptoms manifest.

This is true for the arsenal of nutrients (like zinc lozenges and garlic) and drugs (like cimetidine) that Life Extension® has long urged readers to initiate as soon as a common cold or flu symptom manifests.

For those unable to prevent a full-blown flu infection, scientists have identified a botanical extract that may help speed recovery from the flu.

Faster recovery can allow one to avoid more serious complications that accompany the flu.

Unleashing the Nuclear Bomb

Life Extension recommends early and aggressive action at the first sign of flu symptoms: if you develop flu symptoms, it is critical that you act quickly to halt the rapid replication and spreading of viruses occurring in your body. Go to the nearest health food store or pharmacy and purchase:5

  1. Zinc Lozenges: Completely dissolve in mouth one lozenge containing 18.75 mg of zinc acetate every two waking hours. Do not exceed 8 lozenges daily, and do not use for more than three consecutive days. (You can also keep zinc acetate lozenges on hand in case cold/flu symptoms manifest.)
  2. Garlic: Take 9,000-18, 000 mg of a high-allicin garlic supplement each day until symptoms subside. Take with food to minimize stomach irritation. Some people prefer using aged garlic extract (Kyolic®) in the high dose of around 3,600-7,200 mg a day.
  3. Tamiflu: 75 mg twice daily. This is a prescription drug and is only effective for certain flu viruses. Generic name for Tamiflu is oseltamivir.
  4. Vitamin D: If you do not already maintain a blood level of 25-hydroxyvitamin D over 50 ng/mL, then take 50,000 IU of vitamin D the first day and continue for 3 more days. Slowly reduce the dose to around 5,000 IU vitamin D daily. If you already take around 5,000 IU of vitamin D daily, then you probably do not need to increase your intake.
  5. Cimetidine: Take 800-1,200 mg daily in divided doses. Cimetidine is a heartburn drug that has potent immune enhancing properties. (It is sold in pharmacies over-the-counter.)
  6. Melatonin: 3 to 50 mg at bedtime.

Do not delay implementing the above regimen. Once a flu virus infects too many cells, it replicates out of control and strategies like zinc lozenges will not be effective. Treatment must be initiated as soon as symptoms manifest!

The Critical Post-Flu Period

Man sick in bed

If you've ever suffered from the flu, you know that the infection phase is only the first part of the process.

The typical symptoms are usually abrupt and include fever that can last 3-4 days. Once the infection passes, the recovery period can take twice that long.6

The flu leaves your body in a weakened state that can impact your energy, sleep, concentration, and overall quality of life for weeks.

It's like the aftermath of a hurricane.

Besides producing symptoms such as weakness, fatigue, and cough, the recovery period leaves your immune system in a weakened, vulnerable state.

As researchers searched for a natural way to shorten the post-flu recovery period, they looked at one of the strongest, most resilient plants around: the oak tree.

Hope from the Oak

Image of Germs

Certain species of oak trees are prized for their strength and durability. They can live for centuries. Even after they are cut down for lumber, their wood remains solid and resistant to decay.7

An oak tree's resilience is due in part to producing a wide array of protective plant compounds called flavonoids.

In particular, oak trees contain roburins. These unique tannins are found only in oak trees, where they provide powerful chemical stress-fighting properties.8

Roburins can offer protection for humans as well, especially when it comes to improving energy and fighting fatigue.

Previous studies have shown that French oak wood can help manage weakness and fatigue in chronic fatigue syndrome and moderate liver failure in conjunction with standard care.9,10,11 With this in mind, researchers wanted to find out if French oak wood extract added to the standard management could exert similar fatigue-fighting, energy-boosting effects in older adults struggling to recover from influenza.12

Xofluza™: A Newly Approved Flu Medication

Almost 20 years ago, the drug Tamiflu® (oseltamivir) was approved for use, helping to reduce the duration of symptoms of the flu.

Since the release of Tamiflu, no new antiviral medications with a novel mechanism of action had been approved.

In October of 2018, the U.S. Food & Drug Administration announced the approval of Xofluza™ (baloxavir marboxil) for the treatment of acute uncomplicated influenza in patients 12 years of age and older.13

Xofluza™ represents an entirely new type of antiviral medication. Tamiflu and others like it blocked the final step of virus reproduction, preventing already formed viruses from infecting more cells.14

In contrast, Xofluza™ works at an earlier step in the development of new viruses. It blocks the production of viral mRNA, which is necessary to begin to build the new virus particles in the first place.

Two randomized trials of Xofluza have already been completed demonstrating clinical benefit in the management of flu. When given within the first 48 hours of flu symptoms, a single dose of Xofluza reduced the duration of symptoms to a similar extent as Tamiflu.13

However, the new drug also reduced the duration of viral shedding, or release of virus from the body, which can infect other people, to a greater extent than Tamiflu. This means that Xofluza may help prevent the spread of the flu virus more effectively than previous antiviral medications.14

Xofluza is now a treatment option for individuals 12 years of age and older if started within 48 hours of symptom onset. However, the FDA has cautioned that Xofluza or any other antiviral treatment should not be considered a substitute for yearly flu vaccination, which is an established strategy to help control the spread of the flu virus.13  Not everyone agrees on the FDA’s position regarding flu vaccines.

Faster Recovery from the Flu

Researchers studied 38 people aged 65-75 who had the flu.15

Three days after the acute flu symptoms ended, subjects were divided into two groups: control group continued with standard flu recovery care alone, such as fluids and rest and the supplement group took an additional French oak wood extract (300 mg/day).

After 10 days and 3 weeks follow-up, subjects taking French oak wood extract showed significantly greater improvements on all recovery parameters compared with the control group. These included:12

  • Reduced weakness and heart rate
  • Improved attention
  • Sleep patterns
  • Normalized recovery after effort
  • Improved alterations in working/concentration

The subjects taking French oak wood extract also demonstrated improvements in objective parameters versus control group, such as: 12

  • Higher oxygen saturation levels (a measure of how well oxygen gets from the lungs to the tissues via the blood),
  • Higher hematocrit (which measures what percentage of your blood is made up of oxygen-carrying red blood cells), and
  • Lower concentrations of plasma free radicals (a measure of chemical stress).

These improved biomarkers may explain the improvements in fatigue, cognition/attention, and recovery experienced by the French oak wood extract group versus control group. The more red blood cells and the more oxygen they carry, the better the functioning of all tissues in the body.

The French oak wood extract group also sharply improved their edema (swelling) scores compared with control subjects. Reduced swelling is yet another important indicator of a faster recovery.

Faster Functional Improvement

Woman sick at work

The "Karnofsky score" was included as part of the evaluation. This score assesses patients based on their functional impairment, which gives a better picture of the participants' experience during recovery. 15

At the beginning of the recovery period, both groups had almost identical impairment scores of about 67 (indicating impairment in conducting normal activity or do active work). This makes sense, as the flu can leave a person in such a weakened state that simple tasks like fixing breakfast or walking to the mailbox can lead to serious weakening and energy loss.

Ten days later, the group taking French oak wood extract had a significantly greater improvement than at the beginning of the study, reaching a Karnofsky score of 96.6 (indicating close to normal, no complains or evidence of disease). .

Even after three weeks, the control group, which also showed improvement, did not score as high as the French oak wood extract group did after just 10 days.

Simply put, the individuals taking the French oak wood extract recovered much faster and were able to more quickly resume normal activities.

Ultimately, improving recovery from the flu is more than just a major step in comfort. It has critical implications in fending off more serious, potentially life-threatening ancillary infections.


Man holding head and stomach

Recovery from the flu often lasts longer than the illness itself. For some, slow or incomplete recovery can mean worsening health, with the onset of pneumonia and other complications.

French oak wood extract speeds post-flu recovery. This would potentially allow older adults to get back to their favorite activities faster, while reducing the likelihood of suffering from deadly complications.

Even more important is starting the antiviral protocol described at the beginning of this article as soon as any flu symptom manifests.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.


  1. Available at: Accessed November 9, 2018.
  2. Available at: Accessed November 8, 2018.
  3. Available at: Accesed January 3, 2020.
  4. Available at: Accessed November 13, 2018.
  5. Available at: Accessed January 3. 2020.
  6. Available at: Accessed November 1, 2018.
  7. Available at: Accessed January 3, 2020.
  8. Available at: Accessed November 8, 2018.
  9. Belcaro G, Cornelli U, Luzzi R, et al. Improved management of primary chronic fatigue syndrome with the supplement French oak wood extract (Robuvit(R)): a pilot, registry evaluation. Panminerva Med. 2014 Mar;56(1):63-72.
  10. Belcaro G, Cornelli U, Luzzi R, et al. Robuvit(R) (Quercus robur extract) supplementation in subjects with chronic fatigue syndrome and increased oxidative stress. A pilot registry study. J Neurosurg Sci. 2015 Jun;59(2):105-17.
  11. Belcaro G, Gizzi G, Hu S, et al. Robuvit(R) (French oak wood extract) in the management of functional, temporary hepatic damage. A registry, pilot study. Minerva Med. 2014 Feb;105(1):41-50.
  12. Ippolito E, Belcaro G, Luzzi R, et al. Robuvit(R): improvement of fatigue in medical convalescence. J Sports Med Phys Fitness. 2018 May;58(5):678-83.
  13. Available at: Accessed November 13, 2018.
  14. Kikuchi T, Watanabe A. Baloxavir heralds a new era in influenza virus biology. Respir Investig. 2019 Jan;57(1):1-2.
  15. Available at: Accessed November 2, 2018.