| Vitamin A, Vitamin D, and Cod Liver Oil: Some Clarifications |
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| Written by Sally Fallon and Mary G. Enig, PhD |
| 2005-Feb-26 |
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Read this page in: French Several visitors to our website have noted inconsistencies in various statements about vitamin A, vitamin D and cod liver oil. These issues revolve around questions of dosage and safety. Vitamin A DosageWe have pointed out that concerns about vitamin A toxicity are exaggerated. While some forms of synthetic vitamin A found in supplements can be toxic at only moderately high doses, fat-soluble vitamin A naturally found in foods like cod liver oil, liver, and butterfat is safe at up to ten times the doses of water-soluble, solidified, and emulsified vitamin A found in some supplements that produce toxicity.(1) Additionally, the vitamin D found in cod liver oil and butterfat from pasture-raised animals protects against vitamin A toxicity, and allows one to consume a much higher amount of vitamin A before it becomes toxic.(1-3) Liver from land mammals is high in vitamin A but low in vitamin D, and should therefore be consumed with other vitamin D-rich foods such as lard or bacon from pasture-raised pigs, egg yolks, and oily fish, or during months in which UV-B light is sufficient to provide one with adequate vitamin D. As a general guideline, we recommend the following doses of vitamin A from cod liver oil, along with a nutrient-dense diet that contains other vitamin A-rich foods:
Individuals under stress or wishing to use cod liver oil to treat a disease condition may take much larger doses, even up to 90,000 IU vitamin A per day, for a period of several weeks. Vitamin DThe recommended dosages for cod liver oil provide about 500 IU vitamin D for children, 1000 IU vitamin D for adults, 2000 IU vitamin D for pregnant and nursing women and up to 9000 IU for those taking large amounts of cod liver oil to deal with stress and disease. In 1997, the Food and Nutrition Board of the US Institute of Medicine set the tolerable upper intake level (TUIL) for vitamin D at 2000 IU per day. However, the vitamin D content experts on the Upper Limits Panel objected to this limit, and several prominent vitamin D researchers have called for an upward revision of the limit. Experiments show that even during the winter with a low vitamin D intake, humans will exhaust stores of vitamin D at a rate of 3000-4000 IU per day, an amount that many people require to maintain optimal levels of the vitamin in the blood. Extensive exposure to summer sun at mid latitudes naturally produces levels of vitamin D in the blood equivalent to what is attained by supplementing with a continued daily dose of 10,000 IU, suggesting humans are designed to tolerate such large amounts of vitamin D.(4) If you are a lifeguard or spend a lot of time in the sun, you do not need to take supplemental vitamin D; however you still need to consume adequate vitamin A. Animal studies show that even moderate amounts of vitamin D increase the body's need for vitamin A, whether the vitamin D is provided in the diet or by UV light (2,5). So, if you cut back or eliminate cod liver oil in the summer, be sure to consume plenty of oily fish, liver, butterfat and egg yolks from grass-fed hens to ensure adequate vitamin A. For a discussion of Vitamin D Toxicity, see http://www.vitamindcouncil.org/vitaminDToxicity.shtml This does not mean we do not recommend that some individuals have their vitamin D levels tested. Such testing can be very useful in determining vitamin D status and the effectiveness of cod liver oil or vitamin D supplements. Cod Liver OilAs of June 2007, we recommend the following brands of cod liver oil: In Stores: Garden of Life, regular dose cod liver oil; Nordic Naturals Vitamin D Cod Liver Oil (not Nordic Naturals Regular Cod Liver Oil) Online/Mail Order:
In Europe:
In Australia:
In New Zealand, Carolyn Searle C.B.P., Natural Health, Fax/Phone: 0064-3-382-8866, Email: thrive (at) xnet.co.nz. Green Pasture fermented cod liver oil, High Vit CLO and Butter oil, all in liquid and capsules. In Canada
In Hong Kong, Leung Chun Sun, email: tcleuncsc (at) yahoo.com.hk, carries Green Pasture Cod Liver Oil. Note that 1 scant teaspoon of regular dose cod liver oil provides about 5,000 IU vitamin A while 1 scant teaspoon of high-vitamin cod liver oil provides over 11,000 IU vitamin A. This extra vitamin A helps to protect the polyunsaturated fatty acids from becoming oxidized after they are incorporated into the cell membrane.(6) High-vitamin cod liver oil also contains a higher proportion of vitamin D than does regular-dose cod liver oil, which is necessary to balance the vitamin A. Some of the brands recommended in various articles on our website we no longer endorse because the manufacturer is removing vitamin A out of concerns of toxicity. An adequate dose of vitamin A-reduced cod liver oil may supply more unsaturated fatty acids than is considered safe. Some brands of cod liver oil contain very little vitamin D compared to vitamin A. The ration of A to D in cod liver oil should be 10 to 1 or less. (In one popular brand, the ratio of A to D is almost 100 to 1.) Vitamin A and vitamin D work synergistically and without the vitamin D, the vitamin A could be toxic. Warning: Many brands of cod liver oil are processed to remove all the vitamins A and D and then have synthetic vitamins A and D added back in. These products should be completely avoided as the synthetic versions of A and D are toxic. For those living in Canada or overseas, where our recommended brands are not available, be sure to contact the manufacturer and inquire whether the A and D in their cod liver oil is naturally occurring or synthetic. Please read these December 2008 Cod Liver Oil updates: References
About the Authors
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Sally Fallon Morell is the author of Nourishing Traditions: The Cookbook that Challenges Politically Correct Nutrition and the Diet Dictocrats (with Mary G. Enig, PhD), a well-researched, thought-provoking guide to traditional foods with a startling message: Animal fats and cholesterol are not villains but vital factors in the diet, necessary for normal growth, proper function of the brain and nervous system, protection from disease and optimum energy levels. She joined forces with Enig again to write Eat Fat, Lose Fat, and has authored numerous articles on the subject of diet and health. The President of the Weston A. Price Foundation and founder of 
Mary G. Enig, PhD is an expert of international renown in the field of lipid biochemistry. She has headed a number of studies on the content and effects of trans fatty acids in America and Israel, and has successfully challenged government assertions that dietary animal fat causes cancer and heart disease. Recent scientific and media attention on the possible adverse health effects of trans fatty acids has brought increased attention to her work. She is a licensed nutritionist, certified by the Certification Board for Nutrition Specialists, a qualified expert witness, nutrition consultant to individuals, industry and state and federal governments, contributing editor to a number of scientific publications, Fellow of the American College of Nutrition and President of the Maryland Nutritionists Association. She is the author of over 60 technical papers and presentations, as well as a popular lecturer. Dr. Enig is currently working on the exploratory development of an adjunct therapy for AIDS using complete medium chain saturated fatty acids from whole foods. She is Vice-President of the Weston A Price Foundation and Scientific Editor of Wise Traditions as well as the author of Know Your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils, and Cholesterol, Bethesda Press, May 2000. She is the mother of three healthy children brought up on whole foods including butter, cream, eggs and meat.
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