Abstract
Numerous health benefits are attributed to the n-3 long-chain PUFA (n-3 LCPUFA); EPA and DHA. A systematic literature review was conducted to investigate factors, other than diet, that are associated with the n-3 LCPUFA levels. The inclusion criteria were papers written in English, carried out in adult non-pregnant humans, n-3 LCPUFA measured in blood or tissue, data from cross-sectional studies, or baseline data from intervention studies. The search revealed 5076 unique articles of which seventy were included in the qualitative synthesis. Three main groups of factors potentially associated with n-3 LCPUFA levels were identified: (1) unmodifiable factors (sex, genetics, age), (2) modifiable factors (body size, physical activity, alcohol, smoking) and (3) bioavailability factors (chemically bound form of supplements, krill oil v. fish oil, and conversion of plant-derived α-linolenic acid (ALA) to n-3 LCPUFA). Results showed that factors positively associated with n-3 LCPUFA levels were age, female sex (women younger than 50 years), wine consumption and the TAG form. Factors negatively associated with n-3 LCPUFA levels were genetics, BMI (if erythrocyte EPA and DHA levels are <5·6 %) and smoking. The evidence for girth, physical activity and krill oil v. fish oil associated with n-3 LCPUFA levels is inconclusive. There is also evidence that higher ALA consumption leads to increased levels of EPA but not DHA. In conclusion, sex, age, BMI, alcohol consumption, smoking and the form of n-3 LCPUFA are all factors that need to be taken into account in n-3 LCPUFA research.
Highlights
N-3 long-chain PUFA (LCPUFA) have been shown to be important for neurological development in very early pregnancy[3], during later pregnancy and lactation[4] and cardiovascular health[5,6] and there is emerging evidence for mental health[7]
It is well established that diet and supplementation with n-3 LCPUFA have the largest impact on n-3 LCPUFA levels[10]; research has indicated that factors other than diet play a role[11]
Titles and abstracts which suggested the study identified one or more factors that are associated with the n-3 LCPUFA levels were selected and screened for eligibility
Summary
N-3 LCPUFA have been shown to be important for neurological development in very early pregnancy[3], during later pregnancy and lactation[4] and cardiovascular health[5,6] and there is emerging evidence for mental health[7]. N-3 LCPUFA are important precursors of the eicosanoids, resulting in reduced blood clotting and increased blood flow[8]. It is well established that diet and supplementation with n-3 LCPUFA have the largest impact on n-3 LCPUFA levels[10]; research has indicated that factors other than diet play a role[11]. As researchers may not be aware of the many non-dietary factors associated with the n-3 LCPUFA levels
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