Polyphenols and Pigments in Fish Oil

  June 29, 2017

Ever since Green Pasture began making fermented cod liver oil (FCLO), we have observed that our product is uniquely stable; another way of saying this is that our product has some sort of abilities to resist oxidation.

About two years ago, Dr. Martin Grootveld, an expert bioanalytical chemist, tested our FCLO for oxidative stability. Dr. Grootveld shared a comment in the aftermath of his tests that spurred a concerted effort on our part to better understand our FCLO’s distinctive natural antioxidant system.

“We've also recently performed some heating experiments on your oil, and found that this process (which readily induces and/or perpetuates the generation of lipid oxidation products in many commercially available vegetable oils) generates little or none of these toxic agents in your oil.”

        —Dr. Martin Grootveld, BSc, PhD, FIBMS, CBiol, FSB, FRSC

The following article by Dr. Subramaniam Sathivel explains that a major reason for our fermented cod liver oil’s notable oxidative stability has to do with the ocean’s natural antioxidant system brought forward through the base of the marine food chain.

Findings of European researchers (Clayton et al., 2015; Clayton & Ladi, 2015) provide a partial explanation for Dr. Grootveld’s observation that our FCLO is highly resistant to the lipid oxidation that plagues commercial vegetable oils. Clayton et al. (2015) have reported that lipophilic (lipid-attracting) polyphenols are common bioactive antioxidant compounds in traditional or minimally processed fish oils. According to Clayton et al., these lipophilic polyphenols “likely contribute to the health benefits of oily fish."

In fact, extensive industrial processing may have the effect of reducing the lipophilic polyphenol content in fish oils as well as removing other valuable antioxidant compounds and pigments. As mentioned by Clayton et al. (2015) “the trace ingredients in fish (such as the polyphenols) that likely played a critical role in conferring their original health benefits.”

Dr. Sathivel’s paper elegantly describes the influential relationship between the base of the marine food chain and Green Pasture’s naturally extracted and minimally processed FCLO. I want to thank Dr. Sathivel for sharing his scientific knowledge and experience with Green Pasture and our wider community.    


Clayton, P.R., Sage, L.C., & Eide, O. (2015). Fish oil, polyphenols, and physical performance. Sport Science. No. 4(82), pp. 2–7.

Clayton, P.R. & Ladi, S. (2015). From alga to omega; have we reached peak (fish) oil?. Journal of the Royal Society of Medicine, Vol. 108(9) 351–357.

Photo source :  


Polyphenols and Pigments in Fish Oil

By Dr. Subramaniam Sathivel

Polyphenols are found in terrestrial plant and marine macroalgae (seaweeds). Examples of terrestrial plant based polyphenols include gallic acids or flavones. Marine-based polyphenols are called phlorotannins. There are almost 150 phlorotannins that have been identified from various macroalgae. Arnold and Targett (2002) have suggested that these phlorotannins are formed biosynthetically through the acetate malonate pathway, which is known as the polyketide pathway.

According to third party laboratory results, Green Pasture Product’s cod liver oil contains polyphenols (Table 1), which most likely derive from a cod’s food chain. Phaeophyta (brown algae) species (Fucus distichus, Saccharina latissima, Saccharina groenlandica, and Alaria marginata), Rhodophyta (red algae) species (Porphyra fallax), and Chlorophyta (green algae) species (Ulva lactuca) are commonly found in Alaskan coastal areas (Kellogg et al., 2015). There are a number of small fishes that eat macroalgae. These small fish are often called algae eaters.

Table 1: Green Pasture’s Fermented Cod Liver Oil Analysis

Sample ID

Total Phenol Analysis (TPA) mg Galic eq/kg Oil









Cod fish are an ocean predator that eat small fish, including algae eaters. Green Pasture’s cod liver oil is produced from Pacific cod. The company uses a specific fermentation technique to extract the cod liver oil; they do not use harsh chemicals or heat treatments. Therefore, the extracted oil is able to retain natural bioactive compounds such as polyphenols. The polyphenol content present in their cod liver oil reduces or prevents lipid oxidation (polyphenols are known their antioxidant properties).

Phlorotannins in macroalgae contain bioactive properties that are anti-inflammatory (Sugiura et al., 2013), neuroprotective (Yoon, Chung, Kim, & Choi, 2008), and antioxidative (Zou et al., 2008). Phlorotannins from brown algae have anti-diabetic effects including a-glucosidase and a-amylase inhibitory effects; glucose uptake effect in skeletal muscle; improvement of insulin sensitivity in type 2 diabetics; and a protective effect against diabetes complication (Hong Lee and Jin Jeon, 2013).

Seaweeds are considered a source of bioactive compounds as they are able to produce a great variety of secondary metabolites with a broad spectrum of biological activities. They are an excellent source of vitamins such as A, B1, B12, C, D and E, riboflavin, niacin, pantothanic acid and folic acid as well as minerals such as Ca, P, Na, and K (Dhargalkar & Pereira, 2005). According to Garza (2005) and Turner and Bell (1973), Coastal Alaskan seaweed species provide a source of food for Native Americans/Alaska Natives (NA/AN). Seaweeds including, Porphyra (black seaweed), Palmaria (ribbon seaweed), Nereocystis (bull kelp), and Macrocystis (giant kelp) are important to Northwest tribes. For example, black seaweed and ribbon seaweed are considered important food and herring roe on Macrocystis is considered an important subsistence food (Garza, 2005).

Based on the color, seaweeds are named as (1) green algae (chlorophyta), (2) brown algae (phaeophyta) and (3) red algae (rhodophyta). The classification of the algae is mainly based on their chemical composition. Green algae contain chlorophyll a and b, beta-carotene and xanthophylls; chlorophyll a and b, beta-carotene and xanthophylls are greenish, yellowish, and yellowish or brownish pigments. Brown algae contains fucoxanthin, which is responsible for the color of brown seaweeds. Red algae pigments such as phycoerythrin and phycocyanin are responsible for the color of red seaweeds (Gupta and Abu-Ghannam, 2011).

As mentioned above, Green Pasture Products uses a minimal processing technology to extract cod liver oil from Pacific cod liver. There is a good possibility that pigments are present in the oil and, therefore, the color of the oil could vary from reddish to dark brown. Extensive purification of fish oil may remove the pigments and other bioactive and natural anti-oxidant compounds.



Arnold, T.M. & Targett, N.M. (2002). Marine tannins: the importance of a mechanistic framework for predicting ecological roles. J Chem Ecol, 28:1919–34.

Garza, D. (2005). Common edible seaweeds in the Gulf of Alaska. Alaska Sea Grant College Program, Fairbanks, AK.

Gupta, S. & Abu-Ghannam, N. (2011). Bioactive potential and possible health effects of edible brown seaweeds. Trends in Food Science & Technology, 22: 315-326.

Hong Lee, S. & Jin Jeon, Y. (2013). Anti-diabetic effects of brown algae derived phlorotannins, marine polyphenols through diverse mechanisms. Fitoterapia, 86: 129–136.

Kellogg, J., Esposito, D., & Grace, M.H. (2015). Komarnytsky,s and Lila A. M. Alaskan seaweeds lower inflammation in RAW264.7 macrophages and decrease lipid accumulation in 3T3-L1 adipocytes. Journal of Functional Foods, 15: 396–407.

Sugiura, Y., Tanaka, R., Katsuzaki, H., Imai, K., & Matsushita, T. (2013). The anti-inflammatory effects of phlorotannins from Eisenia arborea on mouse ear edema by inflammatory inducers. Journal of Functional Foods, 5: 2019–2023.

Turner, N. C., & Bell, M. A. M. (1973). The ethnobotany of the Southern Kwakiutl Indians of British Columbia. Economic Botany, 27: 257–310.

Yoon, N. Y., Chung, H. Y., Kim, H. R., & Choi, J. S. (2008). Acetyl- and butyrylcholinesterase inhibitory activities of sterols and phlorotannins from Ecklonia stolonifera. Fisheries Science, 74: 200–207.

Zou, Y., Qian, Z. J., Li, Y., Kim, M. M., Lee, S. H., & Kim, S. K. (2008). Antioxidant effects of phlorotannins isolated from Ishige okamurae in free radical mediated oxidative systems. Journal of Agricultural and Food Chemistry, 56: 7001–7009.

 Photo credit: Photo credit: CATXALOT via Visual hunt / CC BY


Subramaniam Sathivel, Ph.D. Professor of Food Processing Engineering

Dr. SathivelDr. Sathivel is the Professor of Food Engineer at the School Nutrition and Food Sciences and the Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center (LSUAC). Before joined LSUAC, Dr. Sathivel worked five years as an Assistant Professor of Seafood Processing and Engineering at the Fishery Industry Technology Center (FITC), University of Alaska Fairbanks, Alaska. He is responsible for the food process engineering laboratory at the LSUAC, where his projects include design and development of an adsorption technology to purify fish oils and fish protein, value added products, edible films and edible coatings. Dr. Sathivel has published 60 refereed articles, two popular articles, five book chapters, and six pro­ceedings. Dr. Sathivel has an equally respectable record of published abstracts and professional presentations, many of which were invited talks at international scientific meetings and conferences.


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