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Suppression

Cod liver oil

Category: Medicines - non plants

Type

Voluntary

Introduction and description

 

Cod liver oil is a nutritional supplement derived from liver of cod fish.

As with most fish oils, it has high levels of the omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Cod liver oil also contains vitamin A and vitamin D.

It has historically been taken because of its vitamin A and vitamin D content. “It was once commonly given to children, because vitamin D has been shown to prevent rickets and other symptoms of vitamin D deficiency”.

 

Vitamin D is a vitamin that is principally obtained from sunshine as it is made by the skin when we go out in the sun. 

Children in Western society whose hobbies do not involve playing outside, as well as adults who work indoors all the time or who work shifts, still get Vitamin D deficiency, but sadly these days it is hardly ever diagnosed or talked about. 

In many doctor’s surgeries you have to insist on a test to find out if you are deficient, it is not given as a matter of course even if the symptoms match those of vitamin D deficency.

Even in sunny countries there is a  problem as more and more children take to the indoors.  The female muslim world has a particular problem, as the clothes girls and women have to wear permanently exclude them from any sun.

 

Several studies indicate a high prevalence of vitamin D deficiency among young populations.

Information about the vitamin D status in young adult populations from the Middle East is scarce. The vitamin D status can be expected to be influenced by highly different factors between various countries in Europe, the Middle East and Asia.

The aim of this study was to determine the prevalence of vitamin D deficiency in young Qatari children below 16 years of age.
Of the total number of 458 children surveyed, 228 (49.8%) were males and 230 (50.2%) females. The prevalence of vitamin D deficiency among the studied Qatari children was (68.8%), mostly in the age group (11-16) years (61.6%). Vitamin D deficiency was more common among girls (51.4%) than boys (48.6%). Exposure to sunlight was limited in both groups; but even lower in vitamin D deficient children (57.5%) than in normal children (70.6%). ….. Rickets, fractures, gastroenteritis and delayed milestones were all significantly higher in vitamin D deficient children.
The present study revealed that the prevalence of vitamin D deficiency is high in Qatari children and more common in Qatari girls. In the young population in Qatar, vitamin D deficiency appears to result from a combination of limitations in sunlight exposure and a low oral intake of vitamin D.
PMID:  19179999

 

If you glance at the entry for Vitamin D, you will be able to see that the other main source of Vitamin D besides the sun, is fish.  And in the very long list of fishes that provide Vitamin D, at the top of the list is Cod liver oil.  Of all the sources it is by far the highest, furthermore, it tends to be quite a convenient source.  Although I am no believer in supplements, as it is too easy to overdose, Cod liver oil capsules are the one exception.  If you work, are Vitamin D deficient and busy, getting fish into your diet at the level needed to correct the deficiency is not easy, but taking a small capsule with the oil in it is.

In essence, therefore, we might think of cod liver oil as a food rather than a medicine.  But then all the best medicines are food.

A Bit of History

 

Cod liver oil was traditionally manufactured by filling a wooden barrel with fresh cod livers and seawater and allowing the mixture to ferment for up to a year before removing the oil. Modern cod liver oil is made by cooking the whole cod body tissues of fatty fish during the manufacture of fish meal.

There has been some concern recently about cod stocks in general in certain parts of the world where environmental pollution is high. 

The risk of exposure to environmental toxins such as mercury, polychlorinated biphenyls (PCBs), dioxins, and other contaminants, in fish is of major concern in those who care about such things. 

It is worth adding, however, that according to  research, as long as the capsules are from reliable sources, the risk is low.

 

..Large amounts of fish consumption may result in adverse experiences due to the potential presence of environmental toxins such as mercury, polychlorinated biphenyls, dioxins, and other contaminants. The risks of exposure to environmental toxins and hypervitaminosis with fish consumption are substantially reduced through purification processes used to develop selected concentrated fish oil supplements and prescription preparations. Thus, in choosing which fish oil therapies to recommend, clinicians should be aware of available information to best assess their relative safety, which includes the US Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) advisory statement regarding fish consumption, the meaning of certain labeling (such as "verification" through the US Pharmacopeia) and the differences in FDA regulatory requirements between nonprescription fish oil supplements and prescription fish oil preparations, and how all of this is important to the optimal treatment of patients.  PMID:  17368277

Medicinal uses

There are any number of claims made for cod liver oil.  It helps with heart disease, multiple sclerosis, acne, boils, rheumatoid arthritis, even cancer.......

A Norwegian study of more than 68,000 women reported that female cancer patients who took daily cod liver oil supplements had significantly reduced mortality (25% for all cancers, 45% for lung cancer) compared to women who did not take such supplements.

 

But all these studies are actually meaningless, because all it proves is that they may well have been deficient in Vitamin D, deficient in Vitamin A and deficient in all the essential fatty acids that cod liver oil contains. 

In effect they were nutritionally deprived and possibly sun deprived.  Nutritional deprivation has all sorts of knock on effects and all the diseases above, plus a whole load more are a consequence.  The best claim I came across came from patients themselves.  The following comes from the eHealthme website.

Libido increased (increased sexual urge to have sex)  - On Aug, 15, 2014: 379 people reported to have side effects when taking Cod liver oil. Among them, 2 people (0.53%) have Libido Increased. They amount to 0.04% of all the 5,016 people who have Libido Increased on eHealthMe.

 Just in case you think this may be a sort of placebo effect, I suggest you have a look at the entry for Being naked in the sun.  Dionysos knew a thing or two about vitamin D and sun.  I assume that all the other people who have this side-effect, do not consider it to be something that is unwanted.

Chemical constituents

 The table below shows the chemical constituents of cod liver oil.  It is extremely important that you do not overdose.  You do not need 'high strength' cod liver oil, or cod liver oil with added vitamin A, or cod liver oil with added vitamin D or any other of the dangerous combinations that have started to appear in the so called 'health food' market.  All you need is simple cod liver oil.

The Recommended Dietary Allowance of vitamin A is 900 μg per day for adult men and 700 for women, while that for vitamin D is 15 μg per day. The "tolerable upper intake levels" are 3000 μg/day and 100 μg/day respectively, so people consuming cod liver oil as a source of omega-3 fatty acids should pay attention to how much vitamin A and vitamin D this adds to their diet.”

"Per tablespoon (13.6 g), cod liver oil contains 136% of the established daily Tolerable Upper Intake Level (UL) for Preformed Vitamin A (Retinol).  Vitamin A accumulates in the liver, and can reach harmful levels sufficient to cause hypervitaminosis A."

So a tablespoon is too much, which is why the capsule you buy are actually quite small, less than a teaspoon's worth.

USDA National Nutrient Database for Standard Reference  Release 27 Software v.2.0  Basic Report: 04589, Fish oil, cod liver  Nutrient values and weights are for edible portion

Nutrient

Unit

Value per 100 g

Water

g

0.00

Energy

kcal

902

Protein

g

0.00

Total lipid (fat)

g

100.00

Carbohydrate, by difference

g

0.00

Fiber, total dietary

g

0.0

Calcium, Ca

mg

0

Iron, Fe

mg

0.00

Magnesium, Mg

mg

0

Phosphorus, P

mg

0

Potassium, K

mg

0

Sodium, Na

mg

0

Zinc, Zn

mg

0.00

Vitamin C, total ascorbic acid

mg

0.0

Riboflavin

mg

0.000

Niacin

mg

0.000

Vitamin B-6

mg

0.000

Folate, DFE

µg

0

Vitamin B-12

µg

0.00

Vitamin A, RAE

µg

30000

Vitamin A, IU

IU

100000

Vitamin D (D2 + D3)

µg

250.0

Vitamin D

IU

10000

Fatty acids, total saturated

g

22.608

Fatty acids, total monounsaturated

g

46.711

Fatty acids, total polyunsaturated

g

22.541

Cholesterol

mg

570

 And the table shows it perfectly, Cod liver oil provides Vitamin A, Vitamin D and some essential fatty acids.  So if you are deficient in these, it is a medicine.  If you are not deficient it could become a poison.

 

 

References and further reading

Minerva Pediatr. 2009 Feb;61(1):15-22.  High prevalence of vitamin D deficiency in young children in a highly sunny humid country: a global health problem.  Bener A, Al-Ali M, Hoffmann GF.  Department of Medical Statistics and Epidemiology, Hamad General Hospital Hamad Medical Corporation, Doha, Qatar. abener@hmc.org.qa

Am J Cardiol. 2007 Mar 19;99(6A):35C-43C. Epub 2006 Nov 28.  Safety considerations with omega-3 fatty acid therapy.  Bays HE.  Louisville Metabolic and Atherosclerosis Research Center, Louisville, Kentucky 40213, USA. hbaysmd@aol.com

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