Vitamin C

Research Library

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Vitamin C is a water-soluble vitamin found in abundance in foods such as peppers, citrus fruits, broccoli and strawberries. Most animals can synthesize vitamin C endogenously, but humans cannot. Vitamin C is known for its antioxidant properties and ability to fight free radicals. A free radical can be thought of as an “unhealthy” molecule and can harm cells. As cells become damaged, this is what can cause health problems. Many factors can cause free radicals, such as stress, diet, pollution and other environmental factors.

In the 1700s, scurvy was a common problem for sailors on long trips out at sea, causing symptoms such as bleeding gums, poor wound-healing, depression, seizures, and other symptoms leading to death. In 1747, a Scottish Naval surgeon, James Lind, discovered citrus fruits, high in vitamin C, can prevent scurvy. Today scurvy is relatively rare in the United States, but can be a problem in malnourished populations around the world.

Immune system

Vitamin C, also known as ascorbic acid, is a potent antioxidant, which supports the body's defense mechanism against free radicals.

Diving into our immune system a little more - immunity can be broken down into innate immunity and adaptive immunity. Innate immunity is our first line of defense - physical barriers, chemical barriers and cellular defenses. Adaptive immunity, also known as acquired immunity, is our second line of defense (think antibodies). Vitamin C can contribute to immune functioning by supporting our various cellular functions (both innate and adaptive). Neutrophils are a part of the innate immune system and are the body’s primary defenders against invading pathogens.

One study showed the link between Vitamin C and neutrophils. This study was over the course of eight weeks and had 35 participants who consumed two Gold kiwifruit a day, which was estimated to be approximately 259 mg of Vitamin C. Plasma vitamin C levels were monitored weekly and rose to saturation after one week of supplementation. Neutrophil vitamin C levels were measured at week four (baseline) and saw a significant increase at week eight (supplementation interval)(1).

  1. Enhanced Human Neutrophil Vitamin C Status, Chemotaxis and Oxidant Generation Following Dietary Supplementation with Vitamin C-Rich SunGold Kiwifruit.

    Bozonet SM, Carr AC, Pullar JM and Vissers MCM, Nutrients, 2015

Nutrition Gaps

Vitamin C is an essential micronutrient for humans and we don’t produce it in the body. Therefore, it’s important to obtain it through your diet and supplementation.

Support your healthy eating patterns by adding this beneficial nutrient. Fruits and vegetables are loaded with key nutrients such as dietary fiber, potassium and choline - they are also packed with Vitamin C. If your plate isn’t too colorful everyday, you may want to consider supplementation to help with your vitamin C intake.

  1. Vitamin C - Health Professional Fact Sheet

    Office of Dietary Supplements, National Institutes of Health, 2016

Supports seasonal sinus and lung issues

Flavonoids are a group of natural plant compounds that appear in plant leaves and fruit skin. These compounds are not produced by the human body and therefore must be obtained through diet or supplementation. Examples of flavonoids include quercetin, rutin, and hesperidin. Quercetin is commonly found in red wine, tea, kale, and broccoli, whereas the major sources of Rutin include buckwheat, Japanese pagoda, and eucalyptus. Hesperidin, a citrus bioflavonoid, is primarily derived from citrus fruits such as oranges.

Flavonoids mediate inflammatory responses. Flavonoids protect against cellular injury by preventing macrophage activation and inhibition of NF-kB. NF-kB is a group of proteins that help control many functions in a cell, including cell growth and survival. Macrophages release pro-inflammatory cytokines, which are proteins that control the growth and activity of other immune system cells. Flavonoids modulate macrophage activation keeping the immune system in balance.

A systematic review of 14 studies evaluated the efficacy of dietary flavonoids on immune function in healthy adults. One study observed the correlation of missed workdays and flavonoid supplementation. The study found a noticeable reduction of missed work days in the group of participants who had flavonoid supplementation in comparison to the control group. In two studies, significant reductions in symptoms with flavonoid intervention was reported when compared with control intervention.

  1. Quercetin

    TRC Natural Medicines Database, Food, Herbs & Supplements- Professional, 2021

  2. Hesperidin

    TRC Natural Medicines Database, Food, Herbs & Supplements- Professional, 2021

  3. Rutin

    TRC Natural Medicines Database, Food, Herbs & Supplements- Professional, 2021

  4. Chemistry and Biological Activities of Flavonoids- An Overview

    Kumar and Pandey, The Scientific World Journal, 2013

  5. Effect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis

    Somerville et al, American Society for Nutrition. Adv Nutr 7:488–97, 2016

  6. Structure-Activity Association of Flavonoids in Lung Diseases

    Lago et al, Molecules 19, 3570-3595, 2014