Analysis of the omega-3 fatty acid content of South African fish oil supplements : a follow-up study : cardiovascular topics

Abstract

IntroductionGlobally the omega-3 (n-3) fatty acid supplement industry is expanding rapidly while consumers are becoming more aware of the health benefits of n-3 fatty acids. Our group conducted a survey in 2009 on 45 commercially available fish oil supplements on the South African market. The aim of the study was to determine the fatty acid composition and content of supplements for comparison with the claimed contents on the product label. The survey was repeated in 2012 on 63 supplements.MethodsSixty-three commercially available n-3 fatty acid supplements were analysed using gas–liquid chromatography to determine their fatty acid composition and content.ResultsThis analysis has shown an improvement in the accuracy of EPA content (44% in 2009) declared on supplement labels compared to the 2012 (52%) survey. It was also evident that a higher percentage of supplements (13% in 2009 vs 35% in 2012) contained DHA levels higher than declared. In 2009, 64% of supplements cost R2.01 to R5.00 or more to achieve a daily intake of 500 mg EPA + DHA, compared to 81% in 2012. Forty-four per cent of supplements were found to be in the early stages of rancidity [conjugated diene (CD) levels] compared to 73% in 2009. More than 80% of supplements had peroxide levels higher than the recommended content as specified by the Global Organisation for EPA and DHA Omega-3 (GOED). The majority (81%; n = 51) of the supplements under study in 2012 had a 1.1–1.5:1 EPA-to-DHA ratio or less, compared to 56% in 2009. Almost a third (32%) of the supplements in the 2012 survey contained ethyl esters (EE) or a combination of ethyl esters and triglycerides.ConclusionAlthough the results of the 2012 versus the 2009 analysis were encouraging in terms of the accuracy of EPA declared on the supplement labels, the high peroxide levels found in the supplement oils are of concern. High peroxide levels are associated with potential health implications. EE were present in some of the supplements, even though the safety of EE has not been confirmed in vulnerable groups such as pregnant women and children.

Oxidized fish oil in rat pregnancy causes high newborn mortality and increases maternal insulin resistance

“…In addition, 25% exceeded the recommended level of secondary oxidation products (aldehydes and ketones) (4). Similar results have been demonstrated in studies from North America (36,50) and Africa (48). This implies that most women taking fish oil during pregnancy are routinely exposed to oxidation products.…”

“…It represents an important proof of concept that supplementation with oxidized fish oil in pregnancy may be harmful. This is relevant as fish oil supplements are often oxidized at the time of purchase (4,36,48,50) and are commonly taken during pregnancy. Therefore, there is a pressing need for studies examining dose-response relationships between oxidized fish oil consumption and pregnancy outcomes.…”

Bioavailability ofn-3 fatty acids fromn-3-enriched foods and fish oil with different oxidative quality in healthy human subjects: a randomised single-meal cross-over study

“…Recent studies have reported elevated peroxide levels in commercialised fish oil capsules, which have led to some concern that regular consumption of oxidised marine oils may negatively affect human health ( 16 – 21 ) . In a previous study, we did not observe any changes in fasting plasma LC n -3 FA levels, lipids or several other oxidative stress markers after 7 weeks of consumption of oxidised compared with non-oxidised fish oil ( 22 ) .…”

South African seed oils are safe for human consumption

“…The CD content, peroxide value and fatty acid analysis was determined according to the methods described in previous publications. 11 …”