International Journal of
Clinical Images and Medical Reviews
Mini Review

Importance of maintaining and improving immune function by diet, nutrition and exercise
before specific vaccinations and therapeutic drugs for COVID-19
Katsuhiko SUZUKI
Faculty of Sport Sciences, Waseda University, Japan.
Mini Review
In March 2021, vaccination against COVID-19 had just started in Japan. At that time, there were no sufficient therapeutic agents otherthan conventional anti-inflammatory steroids. However, only half ayear later, the vaccination rate of the Japanese people against COVID-19 exceeded 70% and specific medicines using specific antibodies
came into use, resulting in a drastic decrease in the number of infected people in Japan. This experience made us realize once again howamazing the immune system is. Before relying on vaccinations andtherapeutic drugs, it is very important to enhance the immune systemin our daily life, and for this purpose, the role of nutrition and exercise
is very important and cannot be neglected. Maintaining and improv-

lack of physical activity are all risks for lowering immune function.
Therefore, avoiding stress, promoting proper sleep, moderate exercise,and intake of fruits and vegetables were recommended [1]. Supplements such as vitamins C and D, omega-3 fatty acids, and zinc werealso thought to be useful in maintaining immune function when fresh
foods were not available. Lifestyle-related diseases such as obesity anddiabetes lower the immune system [2]. In addition to aerobic exercise, resistance exercise is also effective in preventing these diseases,
and exercise using an online program was recommended during theCOVID-19 pandemic. In particular, a simple method of respiratory
muscle training was introduced in order to prevent respiratory failure
in COVID-19 [1].

ing immune function is important not only for the frail elderly andOn the other hand, mild dietary restriction is known to increase life

diseased people, but also for the healthy general population. In theexpectancy, improve insulin sensitivity, reduce oxidative stress and in-case of the COVID-19 pandemic, not only countermeasures against

flammation, and decrease mortality from cancer and cardiovascular

the pathogen, but also various measures to enhance immune functiondiseases [3]. As for immune function, previous studies have reported

were taken. The author has also been involved in logistical support

that it can be improved by fasting for three days. However, exercise

activities with the cooperation of researchers and medical backup bothand training under fasting conditions may not only cause exhaustion

inside and outside Japan and describe some of the experience/findings

and dehydration, but may also lead to oxidative stress, inflammation,

here.

muscle damage, fatigue and an immunocompromised state. For theseFirst, researchers in Iran and the UK, where the damage caused byCOVID-19 was serious in the early 2020, proposed measures focusing on exercise and nutrition, and international guidelines were published online in August 2020 [1], so I introduced its contents as a corresponding author. As people refrained from going out, there werefewer opportunities for exercise, physical activity and training, andthere were concerns about the decline in physical fitness and immune
function. In order to prevent infection, it is essential to wear masks,
wash hands and ventilate rooms in daily life, but it was also necessary

reasons, the following points of caution for training during the monthlong fasting period (Ramadan), which is a religious event for Muslims,
were presented: intensity, duration and frequency of exercise, recommended timing of food intake and nutrient requirements [3]. In thesame way, the importance of hydration was also pointed out to prevent dehydration and related disorders [3-6]. In order to maintain theimmune system, it is important for the organism to exercise without
excessive stress, and to consume nutrition, water, and rest accordingly[3-5].

to take care not to weaken the immune system. Psychological stress

Furthermore, the importance of exercise and nutrition has begun todue to restrictions on going out, overeating, unbalanced diet, and abe verified in COVID-19 patients. First of all, a case report was pre-*Corresponding Author: Katsuhiko SUZUKI, Faculty of Sport Sciences,Waseda University, Japan.
Email address: katsu.suzu@waseda.jp
Received: Nov 11, 2021 Accepted: Dec 31, 2021 Published: Jan 05, 2022.

Volume 1 | Issue 1 | 2022

Citation: Katsuhiko SUZUKI. Importance of maintaining and improving
immune function by diet, nutrition and exercise before specific vaccinations
and therapeutic drugs for COVID-19. Int Clin Img and Med Rev. 2022; 1(1):1013.

1https://ijcimr.org/
sented in which isometric exercise was prescribed to an overweight

6. Tominaga T, Ikemura T, Yada K, Kanda K, Sugama K, Ma S, Choi,

young female patient, which improved her respiratory function andW, Araya M, Huang J, Nakamura N, Suzuki K. The effects of beveragevital signs and may hasten her discharge from the hospital [7]. Then,intake after exhaustive exercise on organ damage, inflammation andthe importance of bioactive substances secreted from skeletal muscles

oxidative stress in healthy males. Antioxidants. 2021;10:866.

by exercise was discussed in view of the importance of rehabilitation[8]. In addition, a randomized controlled trial reported that patientswith high blood levels of vitamin D and zinc are less likely to become
seriously ill after being infected with COVID-19, and pointed out the7. Hekmatikar AHA, Shamsi MM, Ashkazari ZSZ, Suzuki K. Exercise
in an overweight patient with Covid-19: A case study. Int. J. Environ.
Res. Public Health. 2021;18:5882.

need to consume food components that enhance immune function on

8. Nobari H, Fashi M, Eskandari A, Pérez-Gómez J, Suzuki K. Poten-a regular basis [9].

tial improvement in rehabilitation quality of 2019 novel coronavirus

In COVID-19, preventive measures against infection are essential. For
this purpose, it is important to enhance individual immune function,by isometric training system; is there “muscle-lung cross-talk”? Int. J.
Environ. Res. Public Health. 2021;18:6304.

that is, resistance to infection, by improving lifestyle habits such as

9. Golabi S, Adelipour M, Mobarak S, Piri M, Seyedtabib M, Bagheridiet, nutrition [10-12] and moderate exercise [13-17]. The spread ofR, Suzuki K, Ashtary-Larky D, Maghsoudi F, Naghashpour M. The as-infection may continue to occur due to the emergence of new vari-sociation between vitamin D and zinc status and the progression ofant strains or drug resistance. Each time this occurs, the development

clinical symptoms among outpatients infected with SARS-CoV-2 andand improvement of vaccines and therapeutic agents are expected topotentially non-infected participants: A cross-sectional study. Nutri-progress, but before that, it is fundamentally important to maintainents. 2021;13:3368.

and improve immune function. The author has also been cooperatingwith COVID-19 countermeasures through support activities such asvaccination, healthcare visits to elderly facilities, and health checkups,
and reaffirmed the need for medical research activities that are use-10. Suzuki K. Recent progress in applicability of exercise immunology and inflammation research to sports nutrition. Nutrients.
2021;13:4299.

ful for early detection and early treatment for those in the front-line

11. Taherkhani S, Valaei K, Arazi H, Suzuki K. An overview of physi-positions.

cal exercise and antioxidant supplementation influences on skeletal

Acknowledgments
I thank the editorial staff , Dr. Llion Roberts and Aya Miki for editingof this manuscript.
Conflict of Interest
The author declares no conflict of interest.
References
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2. Suzuki K. Chronic inflammation as an immunological abnormality
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muscle oxidative stress. Antioxidants. 2021;10:1528.
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N, Alizadeh A, Samipoor F, Moslem A, Doaei S, Suzuki K. The effectof vitamin C on pathological parameters and survival duration of critically ill coronavirus disease 2019 patients: a randomized clinical trial.
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angiotensin system and immunomodulatory effects. Front. Physiol.

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16. Takahashi M, Miyashita M, Kawanishi N, Park JH, Hayashida H,Kim HS, Nakamura Y, Sakamoto S, Suzuki K. Low-volume exercise

4. Suzuki K, Tominaga T, Ruhee RT, Ma S. Characterization and mod-training attenuates oxidative stress and neutrophils activation in olderulation of systemic inflammatory response to exhaustive exercise inadults. Eur. J. Appl. Physiol. 2013;113:117-1126.

relation to oxidative stress. Antioxidants. 2020;9:401.

17. Radak Z, Torma F, Berkes I, Goto S, Mimura T, Posa A, Balogh L,

5. Lim CL, Suzuki K. Systemic inflammation mediates the ef-Boldogh I, Suzuki K, Higuchi M et al. Exercise effects on physiologicalfects of endotoxemia in the mechanisms of heat stroke. Biol. Med.

function during aging. Free Radic. Biol. Med. 2019;132:33-41.

2017;9:1000376.

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