Cod Liver Oil: Is it as good as you really think?

Hello my welcome reader,

Originally, I set out to discuss the new craze of graviola (sour sop) juice and its 'cancer killer' ability. The science behind this claim and whether it is anything but desperation but that will have to wait for a later post as a friend of mine recommended I take cod liver oil capsules to ease the clicking in my ankles as well as gaining a plentiful list of benefits associated with the supplement (first table below). Anybody who knows me will know my ankles click ALOT, walking, going upstairs sometimes just standing and bam but I digress.  Nevertheless, this got me wondering, if it really was that good, what have I been doing with my life? And so I took the time to look into the high street products and the initial websites saying just how incredible cod liver oil (CLO) is. But before long I stumbled upon a web page or two suggesting all is not quite as good as it seems. Whatever is?

What is CLO? Where does it come from? Why do you care?

CLO is exactly what it sounds like, oil extracted (or pressed) from the liver of the Atlantic cod (Gadus morhua). For many years CLO has been made by storing cod livers in barrels filled with seawater and left to ferment for approximately a year. Nowadays, there are multiple methods including alkali refining, bleaching, winterization, and deoderization. these remove the precious vitamins and most high street products are sold with synthetic vitamins added however it is possible to restore natural vitamin volume with additional expense. The use of oily fish as medicine has been suggested as early as Hippocrates. The first documented use of CLO as a medicinal substance was recorded in 1789, by 1824 CLO was used to cure rickets and by the 1930's the benefits were firmly established and every kid on the block was taking the capsules as a daily supplement.

The benefits of CLO lie in the ingredients of omega-3 long-chain polyunsaturated fatty acids, vitamin D and A. As a result, in addition to the reduced risk of heart disease, cancer, diabetes and Alzheimer's (4 biggest killers around) CLO could offer the benefits listed below:

So why bother writing a post on this, case closed CLO is a miracle right?

The very dangerous needle in the otherwise healthy hay...

It must be said that there is very little in the way of quality control with regards to CLO and this in itself causes a problem, it means companies can add or take anything from the product. The aforementioned deoderization process leaves little vitamin A + D typically replaced by synthetic substitutes. This is disgusting as an idea that you may not know what you are eating...and yet in the 21st century this stimulates a response along the lines of  'That is bad....but is that not the same with everything we eat unless we make it ourselves?' (my mind wonders again, save it for another post). Furthermore, the toxins in the seas and therefore in the fish, and the fish's liver and in our CLO capsules is on the increase.

However, the main problem stand hand in hand with the benefits associated with the ingredients of vitamin D (vit D) and A (vit A). Vit D comes in five different forms D1-D5, this blog and most nutritional guidelines refer to D2+D3. Without getting too wordy hypovitaminosis D (vit D deficiency) is common in northern climates such as the UK, USA due to the lack of sun and westernised diet. Gordon et al., (2004) conducted a study in Boston observing 24.1% of 307 healthy US adolescents proved to be vit D deficient, of which 14.6% were severely deficient. 42% of the subjects were vit D insufficient. Vit A on the other hand is available in a vast list of veg, some fruit and eggs among other things. As a result, disparity exists with too much vit A and not enough vit D. This fact is made worse by the discovery of a synergistic relationship between vit A + D. Johansson & Melhus (2001) observed a decreased positive effect of vit D with the intake of vit A but the ratios were quite extreme (1:7500 micrograms of vit D:A) however, as little as 3000 international units of vit A has been shown to thwart the disease preventing effects of vit D. How much is 3000 international units? It does depend on the source of vit A but it can be not that much (as little as 900 micrograms), the table below shows the typical values of high street products:

The intelligent readers will have spotted that these products typically include greater volumes of vit A compared to vit D, as much as 800 micrograms. With a standard volume of 5 micrograms of vit D (a third of your RDA for male and female between 19-50 years old). Seven seas have begun to produce CLO capsules containing no vit A, this is a first and can only mean good things, assuming you achieve the correct amounts of vit A in your diet already. I must be clear that vit A is not the bad guy, he is just very common and easy to come by, vit D has a substantial effect on our health and is much rarer, as a consequence we must be careful not to attenuate any positive effects that may be offered by overshadowing with vit A. A meta-analysis of vit A toxicity identified CLO (with vit A) showed decreas in infections in third world countries and showed an increase in infections in developed countries, most likely a result of diet dichotomy. It must also be mentioned that to have too much vit D is speculated to decrease the many positive effects of vit A, but this is difficult to do (without supplements) and years could be spent talking about this product in much, much more detail however I feel you will leave with a little more consideration to the little things you put in your system.

To conclude...

CLO is not a straightforward miracle but does definitely hold potential to improve health. However with our westernized diets requiring less vit A, the poor quality control, toxins in the sea/fish alongside the damaging processes required to produce CLO it is understandable to question whether or not these supplements are anything but a very long game of Russian roulette. But do not be frightened! This is a brief overview for the general public, whether a 21st century health nut or not your well-being should be the number one concern and so use this as home base and look into it yourself.

Your very own health nut,

Chris

Sources:

Cannell, J.J., Vieth, R., Willett, W., Zasloff, M., Hathcock, J.N., White, J.H., Tanumihardjo, S.A., Larson-Meyer, D.E., Bischoff-Ferrari, H.A., Lamberg-Allardt, C.J., Lappe, J.M., Norman, A.W., Zitterman, A., Whiting, S.J., Grant, W.B., Hollis, B.W. & Giovannucci, E. (2008) Cod liver oil, vitamin A toxicity, frequent respiratory infections, and the vitamin D deficiency epidemic. The Annals of Otology, Rhinology, and Laryngology, 117(11): pp864-870.

Gordon, C.M., DePeter, K.C., Feldman, H.A., Grace, E. & Emans, S.J. (2004) Prevalence of vitamin D deficiency among healthy adolescents. Archives of Pediatrics & Adolescent Medicine, 158(6): pp531-537

Hypponen, E. & Power, C. (2007) Hypovitaminosis D in British adults at age 45 y: nationwide cohort study of dietary and lifestyle predictors. The American Journal of Clinical Nutrition, 85(3): pp860-868.

Ruth, A.G (1923) The history of cod liver oil as a remedy. The American Journal of Diseases of Children, 26(2): pp112-116.

http://www.westonaprice.org/blogs/cmasterjohn/new-evidence-of-synergy-between-vitamins-a-and-d-protection-against-autoimmune-diseases/

http://www.jabfm.org/content/18/5/445.1.full.pdf+html

http://articles.mercola.com/sites/articles/archive/2010/03/16/warning-new-proof-confirms-if-you-take-this-supplement-vitamin-d-will-not-work-as-well.aspx