Better Body Clinical Nutrition


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Cod Liver Oil Basics and Recommendations – Part 4

Wednesday, October 25, 2023 3:15 PM

Our recommended brands of cod liver oil (COMING IN FUTURE POST) will provide with the above recommended dosages for cod liver oil about 500-1000 IU vitamin D for children, 1000-2000 IU vitamin D for adults, 2000-4000 IU vitamin D for pregnant and nursing women and up to 9000-18,000 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. 

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. 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 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. Optimal serum vitamin D levels should be in the range of 30-50 ng/mL