Vitamin A

1. Vitamin A: Information

  1. Vitamin A (see also: functions and 7 days or recipes for 100%+ intake for RDA/RDI; nutrient requirement standards)
  2. Vitamin A (additional info)
  3. Oregon State University, Linus Pauling Institute: Vitamin A (Prescription for Health; Micronutrients for Health)
  4. Understanding Vitamin A Units
  5. SONA: Suggested Optimal Daily Nutritional Allowances for Vitamin A
  6. The Vitamin A Story: Lifting the Shadow of Death -- Chapter 7: Rise of the "Anti-infective Vitamin," Shemba, R.D.
  7. Vitamin A -- Tolerance Extends Longevity
  8. Vitamin A -- The Scarlet Nutrient
  9. Vitamin A
  10. Note: As mentioned on some of the above links, high doses of vitamin A are not recommended during pregnancy, or for women hoping to become pregnant soon (there is some debate whether caution is needed, but it is commonly recommended). Also, plant-based precursors to vitamin A called carotenoids are not associated with the concerns for vitamin A from animal sources, such has high amounts of vitamin A from liver. A related video on vitamin A's forms, health effects, and uses in health promotion is included below.

Video: Andrew Saul, PhD, editor of

2. Vitamin A: Food Sources

  1. Vitamin A (inexpensive, readily available, nutrient-dense foods)
  2. Vitamin A food sources
  3. USDA: Food Data Central: Vitamin A food sources
  4. USDA National Nutrient Database, Release 28: Vitamin A
  5. Nutrient Search: Look up top food source of three nutrients at once, such as vitamin A, vitamin C and zinc
  6. Vitamin A

3. Vitamin A: Nutrient Guidelines

  1. Vitamin A: Consumers, Health professionals
  2. Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Vitamins
  3. Dietary Reference Intakes (DRIs): Tolerable Upper Intake Levels, Vitamins
  4. U.S. National Library of Medicine, Vitamin A
  5. Daily Values

4. Vitamin A: Average Nutrient Intake

  1. USDA Food Supply Reports: Chart of Vitamin and Mineral Intake, 100 Years
  2. Average Vitamin A Intake

5. Vitamin A: Conditions Associated with Deficiency

  1. list
  2. Oregon State University, Linus Pauling Institute list

6. Vitamin A Research Studies

6.1 Highlighted Studies

  1. Revealing the targets and mechanisms of vitamin A in the treatment of COVID-19:
  2. Over 95 percent of the USA population falls into the moderate or high risk category of the carotenoid health index (less then optimal health due to low levels of carotenoids, many of which are precursors to vitamin A):

6.2 Immune System

  1. Vitamin A and immune system function:
  2. Vitamin A as "anti-infective" therapy, 1920 - 1940:
  3. A review of micronutrients and the immune system -- working in harmony to reduce the risk of infection:
  4. Vitamin effects on the immune system: vitamins A and D take centre stage:
  5. Over 95 percent of the USA population falls into the moderate or high risk category of the carotenoid health index (less then optimal health due to low levels of carotenoids, many of which are precursors to vitamin A):
  6. Vitamin D, cod liver oil [which is high in vitamins A, D, and omega 3 fats], sunshine, and phototherapy: Safe, effective and forgotten tools for treating and curing tuberculosis infections - A comprehensive review:
  7. Vitamin D, cod liver oil [which is high in vitamins A, D, and omega 3 fats], reduce the incidence of viral respiratory infections:
  8. Development of a rapid, simple assay of plasma total carotenoids:

6.3 Coronavirus/Covid-19

  1. Revealing the targets and mechanisms of vitamin A in the treatment of COVID-19:
  2. Vitamin A and Covid-19:
  3. Low intake of carotenoids and vitamin A associated with viral infections and pneumonia

6.4 Cancer

  1. Nutrition and cancer: a review of the evidence for an anti-cancer diet:

6.5 Cardiovascular Disease

  1. Dietary carotenoids and risk of coronary artery disease in women:

6.6 Longevity

  1. Carotenoids and longevity:

6.7 Optimal Intake Level

(1) Extended quote from Textbook of Natural Medicine, 2006, by Michael Murray, N.D. and Joseph Pizzorno, N.D, and 100+ contributing authors, with 10,000+ medical references cited. The below section of the book was written by Alexander Schauss, PhD, FACN.

The Development of Suggested Optimum Nutrient Intakes

As a result of numerous epidemiologic, clinical, and experimental studies, it is now possible to create SONI [Suggested Optimal Nutrient Intake] levels for vitamins, minerals, and trace elements essential to health.

Nearly 20 years ago [now, in 2021, 30 years ago], an effort was made by Drs. Cheraskin and Ringsdorf at the University of Alabama School of Medicine in Birmingham to establish optimum nutrient intake levels. Their prospective study of the intake levels of vitamins and minerals in humans spanned 15 years. They examined the dietary intake and physiologic levels of nutrients in more than 13,500 subjects, male and female, living in six diverse regions of the United States. The results of their multimillion dollar study was compiled into 153 volumes containing more than 49,000 pages of data.

Only a small but significant portion of their findings were ever released. A series of some 100 research papers were published during a 20-year span ending in the early 1990s, but it seems that their work has been neglected because it is rarely cited in the literature. Cheraskin and Ringdorf’s research, with the assistance of specialists in various disciplines, investigated the health status of study participants through a time-consuming evaluation of each person’s health status over a 15-year period. Each subject completed the following tests and procedures:

  1. The 195-item Cornell Medical Index health Questionnaire (CMI)
  2. Physical and anthropometric measurements
  3. Dental examination
  4. Eye examination
  5. Cardiac function tests, including an electroencephalogram (EEG)
  6. Glucose tolerance test (GTT)
  7. Panel of 50 blood chemistry analyses
  8. A comprehensive study of the diet, including a study of food intake over 7 days

This study attempted to find evidence whether there existed an “ideal” combination of macronutrients, micronutrients, carbohydrates, protein, and fat that would suggest which nutrients contributed to health and longevity, and at what level. The hypothesis of the study was that relatively symptomless and disease-free individuals are healthier than those with clinical symptoms and signs and that this difference was due to the intake of nutrients from the diet and/or dietary supplementation. Of course, any study, even one involving some 13,500 subjects studied prospectively in six diverse geological regions over 15 years has inherent weaknesses and shortcomings. But it remains the only study of its nature that made its findings available to researchers to analyze and mine for data on what optimal nutrient levels in humans living in a Western culture might be.

Cheraskin and Ringsdorf's 15-year study of 13,500 subjects found that the healthiest individuals, meaning those with the fewest clinical symptoms and signs over the life of the study, were those who had consumed dietary supplements and eaten a diet nutritionally dense in nutrients relative to calorie intake.

Added note: For Vitamin A, the Suggested Optimal Nutritional Intake was 1750 to 2000 RAE (for females and males, 19 years and older), 222 to 250% higher than the current RDA figures of 700 to 900 RAE, and about 300% higher than the average intakes of 580 to 649 RAE1.

6.8 Addititonal Studies on Vitamin A

  1. list