Nutrition Joins the Fight against COVID-19

With the incidence of COVID-19 on the rise worldwide there are many questions on everyone’s minds….. What can I do to decrease my risk of catching the coronavirus?   Is wearing a mask and social distancing enough to protect me?  What else can I do?  How can I “boost” my immune system?  Can diet, vitamin and mineral supplements prevent or treat COVID-19?

These are all great questions and as a Registered Dietitian Nutritionist I am asked these questions every day.  Yes, there is a lot you can do to be more proactive, take control of your health and prevent or treat diseases such as COVID-19. 

What is COVID-19?  COVID-19 a respiratory disease caused by a new coronavirus called SARS-CoV-2. 

Who is at highest risk?  COVID-19 can affect all groups of people; however, the elderly and those with underlying medical conditions are at the greatest risk.  Conditions that lead to worse outcomes from COVID-19 include obesity, type 2 diabetes and those with a compromised immune system.   

Can vitamins and minerals help?  While research is needed to answer this question, there are several nutrients that have potential benefit.  Clinical trials are underway that suggest supplementation with Vitamin D, Zinc and Vitamin C may be helpful.   


Vitamin D is critical to ensure our immune systems are functioning properly.  Low levels of 25-hydroxyvitamin D (active form of Vitamin D) are common with older age, lack of sun exposure, corticosteroid use and darker skin.  Preliminary studies suggest that people with lower levels of Vitamin D are more likely to test positive for the coronavirus and have more severe symptoms of COVID-19.   

Some medical professionals are recommending that their patients at risk for COVID-19 start taking a daily Vitamin D supplement to raise their 25-hydroxyvitamin D blood level to reduce their risk of infection. The Institute of Medicine states a blood level less than 30 nmol/L is considered a deficiency; 30 – 50 nmol/L is inadequate; greater than 50 nmol/L is adequate.  Higher levels exceeding 125 nmol/L can be harmful. Ask your physician to test your 25-hydroxyvitamin D level.  If it is low your physician can prescribe the proper dosage of Vitamin D for you.

Dosage: I recommend taking a basic daily multi-vitamin and mineral supplement containing 100% RDA for Vitamin D. The recommended daily dosage for children and adults 1 – 70 years old is 600 IU (15 mcg) per day; over 70 years old, 800 IU (20 mcg) per day. It is considered safe to take up to 2,000 IU (50 mcg) of Vitamin D per day.

CAUTION: Excess Vitamin D supplementation is not helpful and may be actually harmful.  It can overstimulate the immune system and increase the risk of respiratory infections which would be damaging in COVID-19 patients.


Zinc is a mineral that is well known for its importance in our immune systems.  Zinc plays a role in antibody and white blood cell production and fighting infections.  It reduces the number of days someone has a cold and other respiratory tract infections.  People who are deficient in zinc are more susceptible to colds, flu and other viruses.  Elderly people are more commonly deficient in zinc due to poor absorption.  Research indicates that increasing levels of intracellular zinc inhibits coronavirus replication in SARS-CoV-1.  Zinc is currently being researched for the treatment of COVID-19 caused by SARS-CoV-2.  Zinc has been used by many physicians in combination with hydroxychloroquine and azithromycin (Zithromax).

Dosage: I recommend taking a basic daily multi-vitamin and mineral supplement containing 100 – 300% RDA for zinc.  The recommended daily dosage for children is 3 – 11 mg and 8 – 11 mg for adults.    

CAUTION: Daily dosage from supplements should not exceed 40 mg per day without discussing with your physician and/or Dietitian.  Zinc lozenges generally exceed 40 mg; they should not be used for longer than a week or so.  Excessive intake of zinc can cause a copper deficiency and impair absorption of some antibiotics.

Vitamin C

Ascorbic Acid (Vitamin C) is an antioxidant that impacts the overall health of the immune system.  Vitamin C improves the function of white blood cells that fight infections.  A deficiency of Vitamin C may lower resistance to the common cold which is a rhinovirus.  Vitamin C deficiency also increases your susceptibility to a variety of chronic diseases.

High doses of Vitamin C may help people who are critically ill and on ventilators with COVID-19.  Several studies found that a dose of 1,000 – 6,000 mg of Vitamin C (by mouth or intravenously) shortened the time on ventilation by 25%.  High doses of intravenous Vitamin C are currently being tested in COVID-19 patients in the United States and China. 

Dosage:  I recommend taking a basic daily multi-vitamin and mineral supplement containing 100 – 300% RDA for Vitamin C.  The recommended daily dosage for children is 15 – 75 mg and 45 – 90 mg for adults.

An additional Vitamin C supplement may be needed to achieve optimum immune function.  Many healthcare providers suggest higher doses of Vitamin C, 500 mg per day or 500 mg twice per day.   

CAUTION: High doses of Vitamin C may cause gastric distress, diarrhea, increase risk of kidney stones and reduce the effectiveness of certain medications. The dosage of Vitamin C that is considered safe varies with age; 650 mg for 1 – 8 year old; 1,200 mg for 9 – 13 year old; 1,800 mg for 14 – 18 year old; and 2,000 mg for those 19 years and older.  If you choose to exceed these doses, discuss with your physician and/or Dietitian. 

Can the foods I eat have an impact on COVID-19Yes!  The average diet in America is unhealthy and lacking important nutrients needed for a normal functioning immune system.  It is high in saturated fats, trans fat, white refined carbohydrates and sugars.  It is low in fiber, healthy unsaturated fats, antioxidants, vitamins and minerals.   This poor diet contributes to obesity and type 2 diabetes; people in both these groups are at high risk for severe COVID-19.      

In addition to contributing to obesity and type 2 diabetes, the average diet in America has a negative impact on the immune system.  Saturated and trans fats activate the innate immune system leading to chronic inflammation.  The adaptive immune system is inhibited leading to B cell immunodepression resulting in impaired defense against viruses such as the coronavirus.  

The foods you eat have a major impact on susceptibility to COVID-19 and your body’s ability to recover.  I recommend that individuals follow an “anti-inflammatory diet” which avoids saturated fats, trans fat, white refined carbohydrates and sugar.  Consume “real food” such as fresh whole foods, fruits and vegetables, whole grains, lean meats and unsaturated fats.


We often forget the power of our own immune system in protecting us from deadly invaders. Our bodies have the ability to fight viruses and diseases such as COVID-19.  However, the immune system has to be functioning at its optimum level to protect us.  It is our responsibility to nourish our immune system so it can do its job properly.  Diet and supplements have a role in our fight against COVID-19. 


Author: Elizabeth Sauls, MS, RDN