Evidence supporting the use of: Vitamin C
For the health condition: Influenza

Links: Go back one page, Tool main page, Ingredients list, Health conditions list, Body systems list

Synopsis

Source of validity: Scientific
Rating (out of 5): 2

Vitamin C (ascorbic acid) has a long history of being used to support immune function and treat or prevent respiratory infections, including influenza. The rationale stems from its role as an antioxidant and its involvement in immune cell function. Early enthusiasm was driven by Nobel laureate Linus Pauling in the 1970s, who promoted high-dose vitamin C for the prevention and treatment of the common cold and influenza. This popularized its traditional use, but also spurred scientific investigation.

Modern clinical evidence, however, is mixed and generally does not support a strong effect. Meta-analyses and randomized controlled trials have shown that vitamin C supplementation does not significantly reduce the incidence of influenza or upper respiratory tract infections in the general population. Some studies suggest a modest reduction in symptom duration or severity, particularly in individuals exposed to extreme physical stress or with low baseline vitamin C levels. For the average person, the effect is minimal or absent.

Guidelines from reputable organizations, such as the CDC and WHO, do not recommend vitamin C as a treatment or preventive measure for influenza. Nonetheless, vitamin C continues to be used due to its safety profile, accessibility, and lingering public perception of benefit. In summary, while there is some scientific basis for a small benefit in certain populations, the overall clinical evidence for vitamin C as a treatment or preventative for influenza is weak, justifying a low evidence rating.

More about vitamin C
More about Influenza

Other health conditions supported by vitamin C

Abrasions
Abscesses
Acne
Acquired Immune Deficiency Syndrome
Addictions (general remedies for)
Addison's Disease
Adrenal Fatigue
Age Spots
Aging (prevention)
Alcoholism
Allergies (food)
Allergies (respiratory)
Alzheimer's Disease
Anal Fistula or Fissure
Anemia
Antibiotics (alternatives to)
Antibiotics (side effects of)
Anxiety
Arteriosclerosis
Arthritis
Asthma
Athletic and Exercise Aids
Autism
Autoimmune Disorders
Bell's Palsy
Bites and Stings
Bladder Infection
Bleeding (external)
Bleeding (internal)
Blood Poisoning
Boils
Bronchitis
Bruises (healing)
Bruises (prevention)
Burns and Scalds
Cancer (natural therapy for)
Cancer (prevention)
Cancer Treatment (reducing side effects)
Canker Sores
Capillary Weakness
Carbuncles
Cardiovascular Disease
Cartilage Damage
Cataracts
Cervical Dysplasia
Chemical Poisoning
Chemotherapy (reducing side effects)
Chicken Pox
Cholesterol (high)
Chronic Obstructive Pulmonary Disorder
Cold Sores
Colds (antiviral)
Colds (decongestant)
Colds (general)
Colds (prevention)
Colds (with fever)
Colon (atonic)
Congestion
Congestion (bronchial)
Congestion (lungs)
Congestion (sinus)
Conjunctivitis
Contagious Diseases
Convalescence
Copper Toxicity
Cough (dry)
Cough (general)
Cuts
Cystic Breast Disease
Cystic Fibrosis
Debility
Dementia
Denture Sores
Depression
Diabetes
Diabetic Retinopathy
Environmental Pollution
Epstein Barr Virus
Eye Problems
Eyesight (poor)
Fatigue
Fatty Liver Disease
Free Radical Damage
Gall Stones
Gastritis
Gingivitis
Glaucoma
Gonorrhea
Gout
Hair (loss or thinning)
Hair Care (general)
Heart (weakness)
Heavy Metal Poisoning
Hemorrhoids
Hepatitis
Herpes
Hot Flashes
Hypertension
Infection
Infection (bacterial)
Infection (viral)
Infertility
Inflammation
Inflammatory Bowel Disorders
Influenza
Injuries
Knees (weak)
Laryngitis
Lead Poisoning
Lesions
Leucorrhea
Leukemia
Ligaments (torn or injured)
Liver Detoxification
Lyme Disease
Macular Degeneration
Mastitis
Measles
Memory and Brain Function
Menorrhagia
Menstrual Irregularity
Menstruation (scant)
Metabolic Syndrome
Mononucleosis
Mumps
Nose Bleeds
Oral Surgery
Osteoporosis
Pancreatitis
PMS (general)
PMS Type C
PMS Type H
Pneumonia
Post Partum Weakness
Pregnancy (herbs and supplements for)
Progesterone (low)
Prolapsed Uterus
Prostatitis
Radiation Sickness
Rashes and Hives
Restless Leg Syndrome
Rheumatoid Arthritis
Rhinitis
Rhinitis, Allergic
Rosacea
Scars / Scar Tissue
Schizophrenia
Scratches and Abrasions
Scurvy
Shingles
Shock
Sinus Infection
Skin (infections)
Skin Care (general)
Sore Throat
Spider Veins
Spinal Disks
Sprains
Strep Throat
Stretch Marks
Sunburn
Surgery (healing from)
Surgery (preparation for)
Teeth (loose)
Tendonitis
Thrush
Tickle in Throat
Tonsillitis
Tooth Extraction
Toxemia
Triglycerides (high)
Tuberculosis
Ulcerations (external)
Ulcers
Uric Acid Retention
Urinary Tract Infections
Vaginitis
Varicose Veins
Warts
Wounds and Sores
Wrinkles

Products containing vitamin C

Nature's Sunshine Love and Peas (Sugar Free)
Nature's Sunshine Adrenal Support
Nature's Sunshine Bowel Detox
Nature's Sunshine Children's Elderberry Immune
Nature's Sunshine Children's MultiVitamin & Mineral
Nature's Sunshine Cortisol Formula (Nature's Cortisol Formula)
Nature's Sunshine Defense Maintenance
Nature's Sunshine Detox Basics (Best used by 7/31/25)
Nature's Sunshine Dieter's Cleanse
Nature's Sunshine Glandular System
Nature's Sunshine Grapine With Protectors (SynerPro)
Nature's Sunshine Hepatic System
Nature's Sunshine Iron (Chelated)
Nature's Sunshine Love and Peas
Nature's Sunshine Marine Collagen
Nature's Sunshine Marine Glo Collagen
Nature's Sunshine Master Gland Formula®
Nature's Sunshine Mega-Chel
Nature's Sunshine Milk Thistle Combination
Nature's Sunshine MultiVitamin & Mineral (SynerPro)
Nature's Sunshine MultiVitamin & Mineral (Time Release)
Nature's Sunshine Natural Changes
Nature's Sunshine Nature's Prenatal
Nature's Sunshine Nature's Harvest
Nature's Sunshine Nervous System (30 Day Program)
Nature's Sunshine Nutri-Calm
Nature's Sunshine Nutri-Calm
Nature's Sunshine Perfect Eyes
Nature's Sunshine Power Beets Pouch
Nature's Sunshine Power Beets To-Go Packs
Nature's Sunshine Power Greens
Nature's Sunshine Power Greens To-Go
Nature's Sunshine Skeletal Strength
Nature's Sunshine Solstic Twenty-Four
Nature's Sunshine Solstic Immune
Nature's Sunshine Solstic Revive
Nature's Sunshine Structural System (30 Day Program)
Nature's Sunshine Super Supplemental
Nature's Sunshine Super Supplemental (Without Iron)
Nature's Sunshine Super Trio
Nature's Sunshine Vari-Gone
Nature's Sunshine Vitamin C (1000 mg, Time Release)
Nature's Sunshine Vitamin C (1000 mg, Time Release)
Nature's Sunshine Vitamin C Ascorbates
Nature's Sunshine Chewable Vitamin C
Nature's Sunshine Citrus Bioflavonoids (Vitamin C)
Nature's Sunshine Zinc Lozenge