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I have been researching fish oil supplementation, and one thing that concerns me is that fish oil may contain Vitamin A, which is fat soluble. Hypervitamintosis A can occur if too much Vitamin A is ingested.

For example, this article mentions this as a possibility.

I have performed multiple searches, using different terms, and have found only one web page that claims fish oil does not contain Vitamin A, but it has not a single reference, nor does it say how they reached their conclusion. I learned long ago not to believe the first thing I read, especially when it is not substantiated by any data, even when it's the first result in a search.

On average, how much Vitamin A is contained in 1g of fish oil (not cod liver oil)? I have performed multiple searches, and asked two doctors, one nurse, and have not found the answer.

BTW, out of caution, I'll mention that certain oils, such as cod liver oil, can contain high levels of Vitamin A, and are not advised during pregnancy. But for this question, I am only asking about regular fish oil, which is manufactured from the body of the fish, as opposed to the liver.

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  • I asked google how much vitamin A is in fish oil. The answer in the very first hit is virtually none.
    – Carey Gregory ♦
    May 10, 2019 at 0:35
  • @CareyGregory Yes, after much searching that is the only reference I could find also. However, a single web page without any references is not a good answer.
    – RockPaperLz- Mask it or Casket
    May 10, 2019 at 1:17
  • I agree that a single web site isn't good evidence, but the graphic provided by google at the very top of the search results showing fish oil contains no vitamin A is based on USDA data.
    – Carey Gregory ♦
    May 10, 2019 at 1:43
  • To prevent problems, I think it's very important for everyone to understand that the link provided by Carey Gregory is for "herring fish oil", which could be appropriate for this question. However, any blanket statements that fish oil contains "virtually no" Vitamin A is reckless. Fish oil made from the liver of the fish contains high levels of Vitamin A and can potentially be hazardous to people who are pregnant. That's off-topic for this question, but worth mentioning so no one gets the wrong idea.
    – RockPaperLz- Mask it or Casket
    May 10, 2019 at 1:52
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    Don't worry about fish oil as far as Vitamin A is concerned. There may be other reasons to be concerned about fish oil. With fish liver oil, like cod liver oil, the Vitamin A content is listed on the supplement. With all due respect, I think you are overreacting to the danger of Vitamin A. The answer regarding supplementation is "it depends", on such things as age, medical condition, whether pregnant or not, medications taken and so on.
    – Gordon
    May 10, 2019 at 4:00

2 Answers 2

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According to USDA Food Composition Database, 1 gram (or even 100 grams) of fish oil from sardines, herring, salmon and menhaden contains 0 (zero) μg vitamin A.

Tolerable Upper Intake Levels for Vitamin A (The National Academic Press, 2001)

Acute toxicity is characterized by nausea, vomiting, headache, increased cerebrospinal fluid pressure, vertigo, blurred vision, muscular incoordination..., and bulging fontanel in infants. These are usually transient effects involving single or short-term large doses of greater than or equal to 150,000 μg in adults and proportionately less in children.

Chronic toxicity is usually associated with ingestion of large doses greater than or equal to 30,000 μg/day for months or years.

According to other sources, such as Canada Nutrient File (you need to click "generate nutrient profile") and NutritionData, there is also no vitamin A in fish oil. Not sure how much these databases are different from the USDA one, but you can see there are also no other vitamins and minerals in fish oil; or according to National Center for Complementary and Integrative Health: "fish oil supplements are the nonvitamin/nonmineral natural products..."

More sources about vitamin A in fish oil:

  • Drugs.com does not even mention vitamin A in fish oil.
  • Drugbank mentions that vitamin A and some other vitamins can be added to some fish oil supplements.

More about vitamin A toxicity:

Office of Dietary Supplements by NIH.gov mentions some (unreliable) observational studies in which vitamin A in doses as low as 1,500 μg/day have been "associated" with side effects.

According to Linus Pauling Institute, long-term consumption of vitamin A in doses 8,000-10,000 μg/day vitamin A could be toxic.

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  • That's a great concise answer, Jan. Thank you! Before Carey pointed out the USDA Database, I didn't have a single good reference. I still haven't found any evidence to corroborate the USDA's claims (not suggesting they are wrong, but it's stronger to have corroborating evidence). If you find evidence that corroborates their values, please do update your answer.
    – RockPaperLz- Mask it or Casket
    May 10, 2019 at 8:52
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    OK, one thing I can tell you, some other sources mention significantly lower (but still high) amounts of vit A that can cause toxicity. For vit A in supplements, I'll check few other sources.
    – Jan
    May 10, 2019 at 8:54
  • Thanks Jan. If you want to post those sources as well, I will definitely read them. If you have time to summarize them like you did for the NAP reference, then everyone will benefit.
    – RockPaperLz- Mask it or Casket
    May 10, 2019 at 8:57
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Vitamin A is an important Vitamin in my opinion. See, importance for Children 6-59 months https://www.who.int/elena/titles/vitamina_children/en/

So age is a consideration. Here is the Pauling Institute article on Vitamin A, Oregon State Univ. https://lpi.oregonstate.edu/mic/vitamins/vitamin-A This article also discusses the osteoporosis risk.

How well people convert Beta carotene to Vitamin A is also an issue. Should the government continue to allow beta carotene to stand for Vitamin A in our foodstuffs? Stay tuned.

I would not advise a heavy smoker to ingest too much beta carotene. https://www.ncbi.nlm.nih.gov/m/pubmed/20155614/

If the fish oil supplements contained a significant amount of pre-formed Vitamin A, then believe me it would be listed on the bottle because there is a bit of hysteria about "hypervitamintosis A" at present.

(Some young people in America get the idea that if a little preformed Vitamin A helps acne, then a lot of it could help even more, and they may take a lot of the vitamin, without medical supervision, day after day, and this could potentially be a problem.)

The answer regarding supplementation is "it depends", on such things as age, medical condition, whether pregnant or not, medications taken and so on. Work with your doctor to find the right level of Vitamin A for you.

Back to fish oil Omega 3 type supplements, I never know whether the oil could be rancid, or whether it could contain an unhealthy level of heavy metals. They can offer health benefits for the right person, particularly if they become a member at a company like Consumer Labs, and follow the information about the good and bad products in this category. Always inform your doctor of the supplements you are taking.

NB Article: Vitamin A and the retina. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3738993/#!po=0.454545 Type 2 Diabetes: https://www.sciencedaily.com/releases/2017/06/170613111649.htm

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