Why is Cod Liver Oil Good For You? Side Effects & Safety Data

Cod liver oil is a favorite all-around health supplement, but how safe is it? Analyses suggest that fermented cod liver oil may be rancid. Some data also suggest that large doses of regular cod liver oil can cause vitamin A overdose and vitamin E deficiency. Get the study details in this particular post.

Cod Liver Oil Side Effects & Precautions

A high consumption of cod liver oil was associated with some health risks. Because the link was frequently found in cohort studies, this does not automatically mean that cod liver oil caused these conditions.

But, caution is advised, particularly in sensitive populations (children, pregnant women, the elderly, and critically-ill).

Additionally, cod liver oil supplements haven’t been accepted by the FDA for medical use. Supplements generally lack strong clinical research. Regulations set manufacturing criteria for them but do not ensure that they’re safe or effective. Speak with your physician before supplementing.

DHA: Benefits, Side Effects, Dosage, and Interactions

1) Vitamin A vitamin Ratio Imbalance

Some researchers oppose using cod liver oil because of the risk of vitamin A overdose with vitamin D deficiency. Although this ratio imbalance can explain the discrepancy between information on cod liver oil’s influence on bone mineral density, the vitamin A content in cod liver oil has been recently decreased by 75% in Norway.

2) Thyroid Cancer Concerns

A study of 60,000 Norwegians associated the use of fish and cod liver oil with a greater incidence of thyroid cancer. Since thyroid gland tissues are allergic to vitamin D, the improper proportion of vitamin A vitamin D is a possible variable.

3) High Blood Pressure During Pregnancy

An analysis of 549 pregnant girls associated marginally higher intakes of those omega-3 fatty acids found in cod liver oil (more than 0.87 g/day or 1 tsp/5 mL of cod liver oil) in the early phases of pregnancy with an increased incidence of high blood pressure. The dosage associated with the lowest risk was 0.10 — 0.87 g/day (or 0.6-5.0 mL of cod liver oil).

4) Bone Weakness

A Study of over 3,000 girls in Norway associated cod liver oil consumption throughout childhood with reduced bone mineral density. The authors speculated that a drop in vitamin A levels in cod liver oil may prevent this impact, as higher vitamin A level increases the probability of bone fractures.

However, Multiple studies came to opposite findings. This may be due to a recent reduction in vitamin A levels in cod liver oil, which might help restore the equilibrium between vitamin A and vitamin D.

Limited studies suggested an association between cod liver oil intake and pregnancy complications, including thyroid cancer, and bone fatigue. More study is needed.

5) Potentially Increased Bleeding Time

The impacts of cod liver oil on blood clotting are inconclusive. Some research found this oil increased bleeding time, while some didn’t observe this impact.

High levels of cod liver oil may boost the risk of excessive bleeding, vitamin A overdose, and vitamin D deficiency. However, the data remain inconclusive and security seems to vary among products based on their vitamin levels.

Medication Interactions

To help avoid interactions, your doctor should handle all your medications carefully. Make sure to tell your doctor about all drugs, vitamins, or herbs you’re taking. Talk to your healthcare provider to discover how cod liver oil might interact with something else you’re taking.

Cod liver oil could interact with these drugs and supplements:

  • Blood thinners: Cod liver oil may increase bleeding time therefore that it may be dangerous to consume with blood-thinning drugs.
  • Vitamin E: Excess levels of cod liver oil may lead to vitamin E deficiency.

The Dosage of Cod Liver Oil Determines Its Security

Doses Used Safely

Cod liver oil is more likely safe when taken appropriately by mouth.

The next daily doses are safely Utilized in clinical trials:

  • 10 mL for up to 24 weeks
  • 15 mL for 16 months
  • 20 mL to 30 mL for two weeks to 8 weeks

Vitamin RDAs and Tolerable Upper Intakes

Since cod liver oil is a source of vitamins D and A, the recommended daily allowances (RDAs) of these vitamins should not be exceeded. The amount of cod liver oil, that amounts to may change from one product to another.

The RDAs of these two vitamins are:

  • Vitamin E: 900 mcg (3000 units of retinol) for men and 700 mcg (2333 components of retinol) for girls
  • Vitamin D: 15 mcg (600 units) for many adults around 70 Decades of age and 20 mcg (800 units) daily for older adults

Cod liver oil is also likely safe in children, and breastfeeding and pregnant girls if vitamin A and D intakes are within the RDAs.

Clinical Trials report safely using 2.5 mL of cod liver oil every day in children aged 6 months to 1 year and 5 mL daily in children aged 1 year to 5 years for 5 months.

According To a clinical trial, a daily dose of 10 mL of cod liver oil (containing vitamin A 1170 mcg and vitamin D) by mouth was protected from week 17 of pregnancy, through delivery, and or 3 weeks through breastfeeding.

Taking Doses of cod liver oil which contains over the Tolerable Upper Intake Levels (ULs) of vitamins D and A is probably dangerous. This will amount to:

  • Vitamin A: 3000 mcg (10,000 components of retinol) daily for girls and 2800 mcg (9333 components of retinol) daily for adolescents aged 14 years to 18 years.
  • Vitamin D: 100 mcg (4000 units) every day for everyone 9 years of age and elderly

Additionally, higher cod liver oil doses (20-40 mL per day) have been connected with prolonged bleeding time in healthy volunteers. Larger trials should explore this further.

Vitamin And D RDAs shouldn’t be exceeded with cod liver oil nutritional supplements in any people. Check the label and consult your healthcare provider if unsure.

Is Fermented Cod Liver Oil Safe?

Fermented vs. Extra Virgin Cod Liver Oil

Fermented And extra virgin equally refer to the method of extracting the oil in the livers. Fermented cod liver oil is expressed from fermenting cod livers and amassing the extruded oil. Extra virgin cod liver oil is extracted from raw epithelial liver without using heat.

While many tout Fermented cod liver oil as superior to non-fermented oil others assert fermented cod liver isn’t fermented at all but decomposed (and is, thus, rancid and maybe even putrefied). Neither of those claims has been substantiated. Fermented cod liver oil has not been extensively studied, unlike non-fermented cod liver oil.

There is no consensus On whether fermentation of oil can happen, whether fermented cod liver oil is rancid, and how to most accurately test for the rancidity of fermented cod liver oil.

It’s uncertain what fermented cod liver oil is. Manufacturers claim to create it by extracting petroleum from fermented cod livers, but others assert these products aren’t fermented although putrefied and rancid. Unbiased, high-quality analyses and research haven’t been completed.

The Importance of Quality Testing

If You decide to supplement, it is important to purchase cod liver oil from trusted brands. Manufacturers of high-quality cod liver oil supplements provide detailed third-party evaluation results on parameters such as vitamins and fatty acid content, dioxins and PCBs, and heavy metals. Information about the rancidity and oxidation by-products of this supplement must also be made accessible.

A scandal in 2015 attracted attention to a popular brand called Green Pastures which didn’t meet those standards, misleading customers, and possibly putting them at a significant health hazard.

This came as a surprise, as proponents previously claimed that Green Pastures made the only really”conventional” fermented cod liver oil. It quickly became a favorite in the paleo community, despite its own definitely bad, burning taste and dark color.

Dr. Kaayla Daniel Detailed the outcomes of her individual”underground” evaluation of Green Pastures Fermented Cod Liver Oil (commonly branded as Blue Ice). Due to the nature of the experiment, her outcomes have not been printed in science fiction but are available online. She claims to have conducted an impartial scientific analysis in her search for the truth behind popular fermented noodle oil asserts.

On the other hand, there is no way to know how she controlled for Some variables as part of her investigations, who did the analyses (this is indicated as confidential data), and also how precise and adequate the selected tests were to identify certain cod liver oil quality parameters.

In 2015, Dr. Kaayla Daniel ran a “covert” analysis of Green Pastures Fermented Cod Liver Oil, implying that its contents don’t match the label. Although informative, her analysis has major constraints and her results have not been published in peer-reviewed journals.

With this in mind, let’s take a peek at what she discovered.

The Green Pastures Fermented Cod Liver Oil Scandal

Here is we’ll intention to sum up the 100-page record which particulars Dr. Kaayla Daniel’s investigations.

Fermented or Not?

To start with, the analysis indicated that Green Pastures Fermented Cod Liver Oil likely wasn’t fermented in any way. This is why:

  • Lactic acid fermentation requires sugars and other carbohydrates, which cod liver oil does not include
  • The oil’s pH was only slightly acidic (5.2-5.8), less so than that of typical fermented foods (under 4.6)
  • It contained far less lactic acid bacteria which fresh, fermented foods (10 colony-forming components or CFU compared to 1-50 million CFU)
  • Considering that the oil probably was not fermented, it was not preserved either and is potentially dangerous (fermentation preserves food by creating an acidic environment that bacteria can not survive )
  • There’s not any evidence that the oil has been”fermented,” that is, preserved, in almost any other way (e.g. by sun-drying, algae, keeping the fish from the earth for a few days, or submerging it in brine)

Limited analyses suggest that Green Pastures Cod Liver Oil is not fermented.

Vitamin Levels and Rancidity

Next, Green Pastures Fermented Cod Liver contained significantly reduced levels of fat-soluble vitamins than cod liver oil should. Plus, the report indicates that it probably does not contain vitamin D2 but merely contains D3, which is typical of cod liver oil (unlike the company claimed).

Moreover, the product comprised very reduced levels of all sorts of vitamin K. Specifically, its vitamin K2 amounts have been 17-19 ng/g. That is in nanograms Per g, equivalent to approximately 1.7 micrograms/100 g. Chicken, which isn’t among the best K2 sources, contains about 14-32 micrograms/100g.

The supplement also had imperceptible CoQ10 levels.

The most concerning discovery? This product appeared to become rancid. Analyses revealed the following:

  • High peroxidase and free fatty acid levels in the oil imply extreme rancidity, which might be liable for its own “unpleasant” flavor (but more accurate tests are needed to verify this)
  • Average rancidity markers of this oil seem to be acceptable, but this kind of testing probably only can help identify short-term rancidity. This fermented cod liver oil, on the other hand, is supposed to become a product of”long-term fermentation”

These results should be taken with a grain of salt, however. As mentioned, free fatty acid and peroxide levels aren’t a true measure of rancidity in fish oils. More reliable and sensitive tests are wanted.

Another concerning fact is that the supplement appeared to contain about 3% trans fats. Cod liver oil, by all criteria, shouldn’t contain trans fats. This usually means that their product may have been adulterated with another, unknown oil (like processed vegetable oil).

Lastly, the information on the amounts of biogenic amines was contradictory.

Green Pastures Cod Liver Oil appeared to contain much lower levels of fat-soluble vitamins. Contradictory investigations suggested intense rancidity, but that is questionable since it is still unsure how long-term rancidity should be examined.

Is it Cod At All?

Dr. Kaayla Daniel’s analyses indicated that Green Pastures Fermented Cod Liver may not be made from cod at all. Its vitamin levels, omega-3 fatty acid ratio, and DNA profile carefully matched Alaskan pollock, not cod.

For Example, the arctic cod liver must contain far less EPA than DHA (the EPA: DHA ratio is usually 6:10 or 9:14). Analyses reported on the Green Pastures website and people of independent testing companies are near enough and purpose to an exceptionally high EPA to DHA ratio (13.5:6.5 and 16.2:7.4).

If this was not sufficient, Dr. Kaayla Daniel claims that according to DNA analysis showed, the liver is”100 percent Alaskan Pollock.”

One DNA study indicated that Green Pastures Cod Liver Oil can, in Actuality, be Alaskan pollock.

What Next?

Although valuable, this analysis opens more questions than it answers.

We Need more impartial, in-depth research regarding the safety of fresh and fermented cod liver oil. If it comes to fermented cod liver oil, high-quality scientific data are particularly lacking. Both lab-based and individual studies are required.


Raw cod liver oil is likely safe when taken by mouth at about 10 to 15 mL daily.

Higher doses of raw cod liver oil can lead to vitamin A overdose, vitamin D deficiency, and possibly excessive bleeding.

No Valid scientific data are available on fermented cod liver oil. Until sufficient studies are carried out, the security of fermented cod liver oil remains unknown.

In case you choose to supplement, be certain to talk with your health care provider and ask producers for quality certificates.