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

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Synopsis

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

Vitamin D has garnered scientific interest for its potential role in preventing and mitigating influenza (the flu). Several observational studies have noted that individuals with low serum vitamin D levels seem to be at increased risk for respiratory tract infections, including influenza. Vitamin D is known to modulate the innate and adaptive immune responses, enhance the pathogen-fighting effects of monocytes and macrophages, and decrease inflammation. This immunomodulatory effect led researchers to hypothesize that vitamin D supplementation might reduce the incidence or severity of influenza infections.

Randomized controlled trials (RCTs) and meta-analyses have provided mixed results. Some studies suggest that vitamin D supplementation can reduce the risk of acute respiratory infections, particularly in individuals who are deficient or have low baseline vitamin D levels. For instance, a 2017 meta-analysis published in BMJ concluded that vitamin D supplementation was safe and protected against acute respiratory tract infections overall, especially in those who were deficient. However, specific evidence for influenza prevention or treatment is less robust. Some RCTs found no significant reduction in laboratory-confirmed influenza with vitamin D supplementation.

In summary, vitamin D’s use for influenza is primarily justified by plausible biological mechanisms and supportive (though inconsistent) clinical evidence. It is not an established therapy for flu, but maintaining sufficient vitamin D levels may contribute to general immune health and potentially lower risk of some respiratory infections. Further well-designed trials are needed to clarify its role specifically in influenza prevention and treatment.

More about vitamin D
More about Influenza

Other health conditions supported by vitamin D

Acne
Allergies (food)
Allergies (respiratory)
Alzheimer's Disease
Amenorrhea
Anemia
Anorexia
Apathy
Arrhythmia
Arteriosclerosis
Arthritis
Asthma
Autism
Autoimmune Disorders
Backache
Birth Defects (prevention)
Body Building
Broken Bones
Calcium Deficiency
Cancer (natural therapy for)
Cancer (prevention)
Cancer Treatment (reducing side effects)
Cardiovascular Disease
Celiac Disease
Chronic Obstructive Pulmonary Disorder
Colds (antiviral)
Colds (general)
Colds (prevention)
Colds (with fever)
Concentration (poor)
Concussions
Confusion
Congestive Heart Failure
Contagious Diseases
Convalescence
Convulsions
Cramps (menstrual)
Cramps and Spasms
Crohn's Disease
Cystic Breast Disease
Cystic Fibrosis
Dandruff
Debility
Dementia
Depression
Dermatitis
Diabetes
Diabetic Retinopathy
Erectile Dysfunction
Estrogen (low)
Fatigue
Fibroids (uterine)
Fibromyalgia Syndrome
Fibrosis
Grave's Disease
Grief and Sadness
Hair (loss or thinning)
Hair Care (general)
Hashimoto's Disease
Headache (cluster)
Heart (weakness)
Hypertension
Hypothyroid
Infection
Infection (bacterial)
Infection (viral)
Infertility
Inflammation
Inflammatory Bowel Disorders
Influenza
Injuries
Irritable Bowel Syndrome
Itching
Knees (weak)
Leaky Gut Syndrome
Leprosy
Lesions
Leukemia
Lou Gehrig's Disease
Lupus
Lymphoma
Melanoma
Memory and Brain Function
Menopause
Menstrual Irregularity
Mental Illness
Metabolic Syndrome
Migraine
Miscarriage (prevention)
Mood Swings
Multiple Sclerosis
Muscle Tone (lack of)
Muscular Dystrophy
Myasthenia Gravis
Nephritis
Nerve Damage
Nervous Exhaustion
Numbness
Nursing
Obsessive Compulsive Disorder
Oral Surgery
Osteoporosis
Pain (general remedies for)
Pancreatitis
Paralysis
Parkinson's Disease
Peripheral Neuropathy
PMS (general)
PMS Type D
PMS Type H
PMS Type P
PMS Type S
Pneumonia
Polyps
Post Partum Depression
Post Partum Weakness
Pregnancy (herbs and supplements for)
Progesterone (low)
Prostatitis
Psoriasis
Rheumatoid Arthritis
Schizophrenia
Sciatica
Seasonal Affective Disorder
Senility
Tuberculosis