Journal Name:
Cytokine
Article Title:
Inflammatory markers are not altered by an eight week dietary a-linolenic acid intervention in healthy abdominally obese adult males and females
Date Written:
2007
Volume:
38
Number:
0
Page:
101
Author(s):
Nelson, T.L.; Stevens, J.R.; Hickey, M.S.
Article:
Cardiovascular disease (CVD) is the number one cause of death among Americans. There are numerous factors that may increase the risk of CVD including: hypertension, excess weight (particularly abdominal fat), diabetes, smoking, hypercholesterolemia, physical inactivity as well as genetic factors. All of these factors may play a role in the development of atherosclerosis which is highly correlated with progression of CVD. Atherogenesisis is thought to be mediated by local and/or systemic production of pro inflammatory cytokines, and several systemic inflammatory markers have been related to an increased risk for CVD, including C-reactive protein (CRP), serum amyloid-A (SAA), interleukin-6 (IL-6) and tumor necrosis factor-a (TNF-a).
Increased levels of pro-inflammatory cytokines may result from a variety of influences including damage to the arterial wall, accumulation of body fat, as well as specific dietary factors. Accumulation of adipose tissue has been associated with higher levels of IL-6 and TNF-a. Different types of fatty acids have also been associated with pro-inflammatory states including the omega-6 (n-6) polyunsaturated fatty acids (PUFAs), which have been shown to increase the production of interleukin-1, TNF-a andIL-6. The omega-3 (n-3) PUFAs have shown to have anti-inflammatory effects and have been associated with lower levels of several inflammatory markers as well as lower risk for CVD. Not surprisingly, then-6/n-3 ratio has also been studied in association with inflammation and CVD risk, with a lower ratio being protective or more beneficial. There are two sources of n-3 fatty acids including plant based (i.e. canola and flaxseed oils) and animal based (i.e. fish oil).
The purpose of this study was to determine the effect of isocaloric changes in dietary omega-3 fatty acid intake on IL-6, CRP, SAA and TNF-a in abdominally overweight/obese, otherwise healthy, adult males and females. Subjects included healthy adult males and females (79% female, average age 38 years) with increased waist circumference (mean WC=99cm) and body mass index (mean BMI=29.8kg/m2) who were free of chronic disease, not taking medications, and sedentary. Control subjects (n =24) did not to alter their habitual diet and the ALA group (n =27) followed an enriched ALA diet by using flaxseed oil capsules (increasing ALA to 5% of total energy intake) and lowered their dietary fat consumption by a commensurate amount. Fasting blood samples were obtained before and after the 8-week intervention.
No significant effects of supplementing with 5% of calories (11g/day) from ALA on serum levels of IL-6, CRP, SAA, or TNF-a among abdominally obese, but otherwise healthy males and females. These results are contrary to several other studies showing that ALA supplementation decreases inflammatory makers. Many of these studies were very similar to the present study in terms of duration, amount of ALA given, changes in n-6/n-3 ratios, BMIs and exclusion criteria. The primary difference between the present study and those previously carried out were in the age (e.g. older) and clinical status of the populations (e.g. mostly hypercholesterolemic or dyslipidemic).
In this study, ALA concentrations increased 8 times in the plasma lipid fractions and 50% in the neutrophils. EPA concentrations increased 2.5 times in the plasma lipid fractions and neutrophil phospholipids. No changes in DHA in the various phospholipids were noted. *In conclusion, this well-controlled 8-week ALA intervention did not show any significant changes in IL-6, CRP, SAA, or TNF-a among abdominally overweight/obese otherwise healthy males and females. Previous studies showing significant changes in these factors have primarily been among older, male, dyslipidaemic subjects. This study suggests there may be limited beneficial effects of an 8-week ALA intervention on these inflammatory factors among young, healthy, overweight/obese subjects whose inflammatory factors are not elevated.
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