Nutrition • 18 Sep 2020

Nutrition and Immunity

By uci_admin

Nutrition and Immunity

By Karen Lindsay, PhD, RDN

Samueli Early-Career Endowed Chair

Assistant Professor, UCI School of Medicine, Department of Pediatrics

Diet and nutritional status play a critical role in determining immune health. There are many modifiable nutrition factors that influence our resistance to and ability to recover from an infection.

Firstly, our waist circumference is a good indicator of our metabolic health and, in turn, our susceptibility to severe infections. Carrying excess abdominal weight is a major factor predicting poor outcomes in patients with COVID-19.1 Healthy eating and regular exercise will help improve our immunity by reducing inflammation. A healthy waist circumference is <35 inches for women and <40 inches for men.

Consuming a variety of vegetables and fruit provides vitamins, minerals and phytonutrients which the body needs to support detoxification, reduce inflammation, and strengthen the immune system against infection. Aiming to “eat the rainbow” of fruit and vegetables will ensure we benefit from the complete range of protective factors that they provide.

Adequate high-quality protein provides the amino acid building blocks for the immune cells to mount an appropriate attack on invading pathogens (viruses, bacteria) and reduce the risk of severe side effects if we do fall ill. Additionally, many protein-rich foods contain the immune-boosting mineral zinc.2 Consuming approximately two 4 ounce servings of protein rich foods per day will support immune functioning.

Many herbs and spices have potent anti-inflammatory and immune-boosting properties,3 such as ginger, turmeric, garlic, oregano, rosemary and chili pepper. Many plant foods and tea (especially green tea) contain flavanoids that have anti-viral properties. Quercetin, a flavonoid found in onions, capers, dill, oregano and broccoli, may be particularly beneficial for fighting viruses that affect the respiratory tract.4

Lastly, the foods we avoid can be just as important as those we consume. Consuming sugary (e.g. candy, soda, cookies) and processed starchy foods (e.g. white bread, fries, pastries) lead to elevated blood sugar levels that suppresses the immune system and increases risk of severe viral reactions.5 Since these foods provide no nutritional value, they are best avoided to protect our immune and metabolic health.


  1. Huang Y, Lu Y, Huang YM, et al. Obesity in patients with COVID-19: a systematic review and meta-analysis. Metabolism. 2020;113:154378. doi:10.1016/j.metabol.2020.154378
  2. Gammoh NZ, Rink L. Zinc in Infection and Inflammation. Nutrients. 2017;9(6):624. Published 2017 Jun 17. doi:10.3390/nu9060624
  3. Serafini M, Peluso I. Functional Foods for Health: The Interrelated Antioxidant and Anti-Inflammatory Role of Fruits, Vegetables, Herbs, Spices and Cocoa in Humans. Curr Pharm Des. 2016;22(44):6701-6715. doi:10.2174/1381612823666161123094235
  4. Somerville VS, Braakhuis AJ, Hopkins WG. Effect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis. Adv Nutr. 2016;7(3):488-497. Published 2016 May 16. doi:10.3945/an.115.010538
  5. Bode B, Garrett V, Messler J, McFarland R, Crowe J, Booth R, Klonoff DC. Glycemic Characteristics and Clinical Outcomes of COVID-19 Patients Hospitalized in the United States. J Diabetes Sci Technol. 2020 Jul;14(4):813-821. doi: 10.1177/1932296820924469.
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