Don’t believe the claims made for nutritional products that are supposed to boost your immunity and protect you from infections, unless you suffer from a specific medical condition or deficiency that can be corrected by that product. The current evidence shows that you are at increased risk for infection with, and severity of, COVID-19 if you have a medical condition that interferes with your immune system such as diabetes, high blood pressure, obesity, heart disease, liver disease, kidney disease, and so forth.

Correctable Risk Factors for COVID-19 that Everyone Should Check
Vitamin D. Blood levels of hydroxy vitamin D should be above 30 ng/mL. A review of 40 studies showed that adequate vitamin D reduced the frequency and severity of COVID-19 infections and hospital admissions, and lowered the death rate (BMJ, Oct 5, 2020;371:m3872). Another review of 86 papers showed the benefits of vitamin D for all aspects of COVID-19 infections (Front Public Health, Sept 10, 2020;8:513). Several studies show that vitamin D deficiency has been associated with increased death rate from COVID-19 (Scientific Reports, Nov 19, 2020;10:20191; Eur J of Endo, medRxiv, May 7, 2020; JAMA Netw Open, Sept 3, 2020;3(9):e2019722).

Vitamin B12 should be above 300 pg/mL.

Blood sugar should be below 145 mg/dL one hour after eating a meal. A study from Wuhan, China showed that non-diabetic COVID-19 patients with high blood sugar levels on admission to the hospital were more than twice as likely to die within a month and four times more likely to suffer the most serious complications caused by the disease (Diabetologia, July 10, 2020). The authors concluded that on admission for COVID-19, a fasting blood glucose level higher than 125 mg/dL (7.0 mmol/l) is an independent predictor of death within 28 days in patients with COVID-19 without a previous diagnosis of diabetes. A study from the U.S. also showed an increased death rate for COVID-19 patients admitted to hospitals with high blood sugar levels (J Diabetes Sci Technol, May 9, 2020). Several previous studies show that diabetics are at markedly increased risk for dying from heart attacks, strokes, cancer and infections (Lancet, 2018;391(10138):2430–2440), and people who have high blood sugar levels on admission to a hospital for pneumonia are at increased risk for dying in the hospital (BMJ, 2012;344:e3397).

Overweight. You are considered to be overweight if you can pinch more than two inches of fat underneath your skin near your belly button. A review of 4,103 patients found that obesity and its resultant inflammation, heart disease and diabetes are the most common conditions found in patients requiring hospitalization with COVID-19 (Physician’s Weekly, published online April 14, 2020). Another study of 3,615 patients found that in patients under 60 years of age, being obese more than doubled the chance of needing to be hospitalized (Clinical Infectious Diseases, April 9, 2020). Other studies show that obesity (body mass index [BMI] greater than 30) is a major risk factor for dying from COVID-19 (Lancet, April 1, 2020), and the more you weigh, the more likely you are to need to be put on a ventilator which markedly increases your chance of dying (Obesity, April 9, 2020). Obesity leads to an overactive immune system called inflammation (Adv Nutr, 2016;7:66-77) that interferes with the body’s ability to kill invading germs (Epidemiology, July 2015;26(4):580-589). Obesity-related chronic inflammation prevents your immune system from producing cells and cytokines to kill invading viruses (Environ Toxicol Pharmacol, 2015;40(3):924-930).

Other conditions that increase risk for severe infection with COVID-19 include:
• Cancer
• Chronic kidney disease
• Chronic lung disease
• Dementia or other neurological conditions
• Diabetes
• Heart disease
• Hemoglobin blood disorders such as sickle cell disease (SCD) or thalassemia
• HIV infection
• Prolonged use of corticosteroids or other immune suppressants
• Liver disease
• Pregnancy
• Smoking (current or former)
• Organ or blood stem cell transplant
• Stroke
• Substance use disorders
• Advanced age. More than 80 percent of COVID-19 deaths occur in people over age 65, and more than 95 percent are in people over the age of 45.

My Recommendations
People with any of the conditions listed above should get vaccinated as soon as possible to minimize their risk for infection with COVID-19. Nutritional supplements on the market today cannot be expected to help protect you from COVID-19 or other infections unless you suffer from specific deficiencies that can be corrected. Your doctor can draw blood tests for vitamin B12 and vitamin D levels to see if you are deficient in these vitamins. You can also help to strengthen your immune system by eating an anti-inflammatory diet, exercising regularly, not smoking, avoiding overweight, and following your doctor’s instructions for treating any medical condition you may have.