Frequently Asked Questions: Ear infections, cod liver oil, and selenium
- What is the difference between cod liver oil and fish oil?
- What company made the supplements used in this study?
- Why did the researchers use lemon-flavored cod liver oil?
- Is there a problem with the purity of cod liver oil?
- There are many brands of cod liver oil. Are they all basically the same?
- Is cod liver oil safe for children?
- It is difficult to find a vitamin/mineral preparation for children that contains selenium. Why is selenium important?
- The different preparations of cod liver oil and vitamin/minerals for children are confusing. Why can't Dr. Linday tell me exactly what my child should take?
- Were there any children with autistic spectrum disorders included in this research on ear infections?
- Is there any research concerning cod liver oil for children with autistic spectrum disorders?
- Are these supplements kosher?
What is the difference between cod liver oil and fish oil?
Both cod liver oil and fish oil contain omega-3 fatty acids, including EPA (eicosapentaenoic acid) and DHA (docosapentaenoic acid). The difference is that cod liver oil also contains vitamins A and D; fish oil does not contain these vitamins. Cod liver oil is made from the liver of the cod fish; fish oil can be made from the body of several different kinds of cold water fish.
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What company made the supplements used in this study?
J. R. Carlson Laboratories, Inc. (Arlington Heights, IL) donated the nutritional supplements used in the supplementation study; Dr. Linday has no other affiliation with Carlson laboratories. The supplements used in this study were Carlson’s lemon-flavored cod liver oil (manufactured by Peter Möller of Oslo, Norway), and Carlson’s Scooter Rabbit chewable vitamins and minerals.
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Why did the researchers use lemon-flavored cod liver oil?
Compliance is the process of getting people to take the supplements and/or medicines that have been prescribed for them. Taste can be important for compliance, especially for young children, who need to take liquids because they cannot swallow capsules. In preliminary work, Dr. Linday found that young children liked the lemon-flavored cod liver oil used in this study.
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Is there a problem with the purity of cod liver oil?
Over the years, our environment has become increasingly polluted. For example, from the 1930s to the 1970s, chemicals known as polychlorinated biphenyls (PCBs) and dioxins were widely used for industrial purposes. Although their use is now severely restricted, these chemicals last for a long time and they are therefore still present in our environment, including our oceans, where they can accumulate in fish. There are now strict criteria for the amount of these chemicals that are allowed in fish oil and cod liver oil to be consumed by people. The lemon-flavored cod liver oil we used in this research met these strict criteria. Read the product label and, if necessary, contact the manufacturer.
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There are many brands of cod liver oil. Are they all basically the same?
As discussed above, there are differences in flavor and purity, which are important considerations when choosing a cod liver oil preparation. In addition, preparations may also vary in the amount of vitamin A and vitamin D that they contain. For example, Carlson's lemon-flavored cod liver oil now contains 500-1200 IU (International Units) of vitamin A per teaspoon. However, the Carlson's lemon-flavored cod liver oil we used previously to perform this research contained 2000-2500 IU of vitamin A per teaspoon. Many other marketed cod liver oils contain 5000 IU of vitamin A per teaspoon. On the other hand, some preparations of emulsified cod liver oil contain 5000 IU of vitamin A per tablespoon.
Carlson's lemon-flavored cod liver oil currently contains 400 IU of vitamin D. However, cod liver oil preparations by other manufacturers have very little vitamin D. Again, read the product label and, if necessary, contact the manufacturer.
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Is cod liver oil safe for children?
Cod liver oil is safe when a preparation of sufficient purity is given in the correct amount and in the correct way. See the section on DOSING for additional information on this important question. Children with a history of fish allergy were excluded from this research.
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It is difficult to find a vitamin/mineral preparation for children that contains selenium. Why is selenium important?
Children have lower levels of plasma selenium than adults. Selenium is a trace metal that is an essential part of a free radical scavenging enzyme known as glutathione peroxidase, which is important in "cleaning up" free radicals. Free Radicals are molecules, or parts of molecules, that are highly reactive chemicals. Free radicals can damage lipid (fatty) membranes by a process known as lipid peroxidation; they can also damage proteins and DNA, and they are important in inflammation.
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The different preparations of cod liver oil and vitamin/minerals for children are confusing. Why can't Dr. Linday tell me exactly what my child should take?
Dr. Linday is a physician (medical doctor; M.D.). According to current medical practice, a physician may only prescribe for a person that he/she has examined. If a physician has not examined a patient, the physician may not prescribe a supplement or a medication for that patient whether by e-mail, telephone or regular mail; this is true even if the supplement is available in a health food store or the medication is available over-the-counter in a drugstore. Recently, some medications have become available over the Internet, but this is considered controversial.
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There were no children with autistic spectrum disorders included in this research on ear infections. Children with known medical problems who were taking regular medication, and children with developmental disorders or syndromes, were not eligible to enter these studies.
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Is there any research concerning cod liver oil for children with autistic spectrum disorders?
Dr. Mary Megson has experience treating children with autistic spectrum disorders with cod liver oil, and information is posted on her web site; (see the LINKS page).
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While we are not aware of any kosher improprieties in the nutritional supplements used in our research and discussed on this web site, these supplements are not certified as kosher. A cod fish has both fins and scales; the cod liver oil is manufactured in Norway to pharmaceutical standards. The label for Carlson's Scooter Rabbit chewable vitamins and minerals states that the inactive ingredients are "fructose, sorbitol, plant cellulose, magnesium stearate, vegetable stearin, citrus flavor." The label also states that the tablets are "Preservative -free. Natural color. Natural lemon flavor. Wheat-free. Yeast free."
Please give this information to your family's rabbi so that you may discuss this question with him/her. Please be aware that most prescription medicines are not certified as kosher.
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DISCLAIMER:
The information on this web site is provided for educational purposes only; it is a general reference for healthcare consumers and providers; it is not a prescription for any individual person. It is important that you consult your child’s qualified healthcare provider before implementing any of the research discussed on this web site.
Copyright © 2002, Linda A. Linday, M.D.. All rights reserved.
Revised: 06/24/10.
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