A Diet with 3% of Energy from a Mixture of Omega-3 Fatty Acids Significantly Increases in Vivo Lipid Peroxidation in Postmenopausal Women

Dietary omega-3 (n - 3) polyunsaturated fatty acids (PUFA) are recommended by public health organizations to reduce the risk of cardiovascular disease, and several epidemiological studies have suggested there is an inverse association between n - 3 intake and human cancers. However, n - 3 are susceptible to an increase in lipid peroxidation in the human body. As part of a crossover dietary intervention study of a diet (20% of energy from fat) with or without an additional 3% of energy from a mixture of n - 3 (with 5.36 g α-linolenic acid and 1.45 g eicosapentaenoic acid and docosahexaenoic acid per 2000 kcal per day), we measured total in vivo lipid peroxidation in healthy postmenopausal women (n = 15). Our results indicated that the diet with 3% of energy from n - 3 significantly increased the urinary concentrations of total polar lipophilic aldehydes and related compounds produced via lipid peroxidation (p α, β-unsaturated hydroxy aldehydes 4-hydroxy-2-trans - hexenal (p trans -decenal (p < 0.05) compared to the diet with less than 1% of energy from n - 3. This is also the first study to document the presence of 4-hydroxy-2-trans -decenal in the urine of individuals consuming n - 3. These results demonstrate that an increase in 3% of energy from dietary n – 3 increases in vivo lipid peroxidation.

Retardation of 4-Hydroxy-2-Transnonenal (HNE), a Toxic Aldehyde Formation by Antioxidants in Heat-Treated Corn Oil at Frying Temperature

The antioxidative properties of four antioxidants such as rosemary extracts (RE), tert-butylhydroquinone (TBHQ), ascorbyl palmitate (AP), citric acid (CA) and their mixtures were investigated on the formation of 4-hydroxy-2-transnonenal (HNE) in commercial corn oil heated at 185°C for up to 6 hours. Among the antioxidants 100 ppm RE and a mixture of 200 ppm tertiary butylated hydroquinone (TBHQ) + 100 ppm ascorbyl palmitate (AP) + 50 ppm citric acid (CA) exhibited excellent antioxidative activity, as determined by the thiobarbituric acid reaction (TBARS) assay, measuring the formations of the secondary lipid oxidation products and by high-performance liquid chromatography (HPLC), measuring the formation of the toxic α, β-unsaturated hydroxyaldehyde HNE after heat treatment of corn oil at 185°C up to 6 hours. TBHQ, AP and CA alone did not show much protective properties. The synergistic effects of TBHQ + AP + CA mixture shown to reduce the formation of HNE after 6 hours heat-treated corn oil by 27%. RE 100 ppm was also found to be a very effective antioxidant, reducing the formation of HNE after 6 hours heat-treated corn oil in the same condition by 29%.

4-Hydroxynonenal (HNE), a Toxic Aldehyde in Fried Chicken from Fast Food Restaurants and a Grocery Store

The lipid oxidation product, the toxic 4-hydroxynonenal, was measured for fried chicken in commercial samples from two fast food restaurants and one commercial establishment. The fried chicken samples were breasts, thighs, chicken nuggets and popcorn chicken. Fried chicken samples were separated to breast skin and meat, and thigh skin and meat. Chicken nuggets and popcorn chicken were not separated from the coating materials and the meat was analyzed together. Samples were analyzed for total fat, fatty acid distribution, reactivity with thiobarbituric acid (TBAR), measuring the secondary lipid peroxidation products such as aldehydes, ketones and related carbonyl compounds. Samples were analyzed for HNE, a toxic aldehyde using high performance liquid chromatography (HPLC). Fatty acid distribution showed in breast and thigh meats, a higher level of palmitic acid, compared to the breast and thigh skins. TBAR values were significantly higher in all breast meats compared to skins. TBAR values were significantly higher in thigh meat than in skin samples. HNE concentrations (μg HNE/g fat) were significantly very low in breast skins compared to breast meat. HNE concentration was generally higher in thigh meat than skin but not in every sample. In chicken nuggets, both the TBAR value and HNE concentration were much higher from one establishment than from the two others. Chicken nuggets TBAR and HNE concentrations resembled one of the chicken nugget samples. The average toxic HNE concentration for 100 g fried chicken breast (skins + meat) was 12.55 μg and for thighs (skin + meat) was 26.76 μg. The average total HNE concentration was 2.1 times higher in the fried chicken thighs than in the breasts. It is clear that HNE is produced during the heating process of oils and incorporated into the fried meat and skin samples during the frying process. If HNE, a toxic aldehyde, is consumed with the food, over long periods of time it could be related to a number of pathological conditions.

Comparison between High-PUFA and Low-PUFA Fats on Lipid Peroxidation and LDL Oxidation

This study was conducted to determine the effects of a low polyunsaturated fatty acid (PUFA) 21 diet versus a high-PUFA diet on lipid peroxidation and on low density and very low density lipoprotein (LDL + VLDL) oxidation in vivo. Rats were fed 10% beef tallow (BT) or 10% soybean oil (SO) diet for 21 weeks. Lipid peroxidation was measured by assessing urinary 24 excretions of secondary lipid peroxidation products, by HPLC and by measuring thiobarbituric acid reactive substances (TBARS) in liver tissue. Plasma LDL + VLDL in vivo oxidation was measured by conjugated diene concentration and TBARS;ex vivo resistance to copper-induced oxidation was also assessed. Total urinary aldehydes, twelve individual urinary aldehydes, and TBARS in the liver were significantly lower in the BT group compared to the SO group. Plasma LDL + VLDL was significantly more resistant to copper-induced ex vivo oxidation to the BT group compared to the SO group. However, in vivo plasma LDL + VLDL oxidation levels measured as conjugated dienes and by TBARS were not significantly different. In general, the low-PUFA BT diet appears to have a protective effect on in vivo lipid peroxidation compared to the high-PUFA diet, but not on in vivo plasma LDL + VLDL oxidation.

The Antioxidant Activity of Barley Malt Rootlet Extracts in Heated Corn Oil at Frying Temperature

In this study the antioxidant activity of barley malt rootlet (BMR) extracts was evaluated in heat treated corn oil up to 5 hours at 185°C frying temperature. The antioxidant activity of BMR extracts was measured at 25, 50, 100 and 150 ppm concentrations. The free and bound antioxidant phenolics were extracted from BMR using three different extraction methods. Conventional solvent extraction (CSE), microwave assisted extraction (MAE) and autoclave assisted pretreated solvent extraction (APSE). In the present experiment, the total phenolic content and antioxidant activity of the various extracts were measured. Thiobarbituric acid reactive substances (TBARS) assay was used to evaluate the ability of the BMR to protect lipid peroxidation in corn oil at 185°C frying temperature. The formation of TBARS at 5 hours of heat treated corn oil has shown similar antioxidant levels in 150 ppm butylated hydroxytoluene (BHT) or MAE free phenolic extract added to corn oil. TBARS value for BHT was 1.896 ± 0.013 μg/mL of corn oil and for MAE was 1.896 ± 0.034 μg/mL of corn oil. The highest level of antioxidant activity was found for the free phenolic extracts. The order of inhibition of oxidation was found to be for free phenolics as follows: BHT (100 ppm) > APSE (50 ppm) > MAE (100 ppm) > CSE (100 ppm).