Trans Fat Supplementation Increases UV‐Radiation‐Induced Oxidative Damage on Skin of Mice

Abstract

We evaluated the influence of fish oil (FO, rich in n-3 FA), soybean oil (SO, rich in n-6 FA) and hydrogenated vegetable fat (HVF, rich in trans FA) on the oxidative status and viability of skin cells of mice exposed to ultraviolet radiation (UVR). Mice were supplemented with FO, SO or HVF for three months and exposed to UVR (2.72 mJ/cm(2)) for 2 days. One day after the last UVR session, the FO group showed higher levels of n-3 fatty acids (FA), while the HVF showed higher incorporation of trans FA (TFA) in dorsal skin. UVR increased lipid peroxidation and protein carbonyl levels of the HVF and to a lesser extent of the control and SO groups. Although all irradiated groups showed increased skin thickness, this increase was slighter in FO mice. UVR exposure reduced skin cell viability of the control, SO and HVF groups, while FO prevented this. Catalase activity was reduced independently of the supplementation and SOD level was increased in C and FO groups after UVR exposure; FO prevented the UVR-induced increase in glutathione levels, which was observed in skin of the control, SO and HVF mice. Our results showed the beneficial effects of FO supplementation, as well as the harmful effects of trans FA, whose intensity can increase vulnerability to skin diseases.

Influence of Trans Fat on Skin Damage in First‐Generation Rats Exposed to UV Radiation

“…These results are consistent with those reported by Rosenthal and Doloresco , who demonstrated that human skin fibroblasts readily incorporate exogenous free FA into cellular phospholipids and triacylglycerol, facilitating the nutritional modification of cellular composition. In fact, recent studies of our group showed that 90 days of supplementation with SO, fish oil and HVF was sufficient to change the skin FA incorporation in rodents, thus affecting the UVR exposure‐induced damage . Our findings also showed that the MUFA incorporation in the skin of HVF group was higher than that observed in the control group.…”

“…SO was used as a control group due to its consumption worldwide and mainly due to its adequate levels of PUFA. The FA profile of each supplemented fat (SO or HVF) and chow was determined as described previously . The experimental supplements were isocaloric in order to prevent metabolic differences between animals, which could cause interferences in the antioxidant defense system .…”

“…Due to the presence of vitamin E (Rexall Sundown INC., Boca Raton) (0.037 UI per 100 g) in the SO, which was purchased in a local market, this vitamin was added to HVF, in order to maintain the same intake of this antioxidant agent in all experimental groups. Animals received these supplementations once daily by orogastric gavage (oral route) (3 g kg −1 ) from pregnancy to lactation . Immediately after weaning (postnatal day 21), one female pup from each litter was kept in the same maternal supplementation (C‐SO and HVF) until the end of experiment (150 postnatal day).…”

“…A single supplement dosage from prenatal period until adulthood of the first generation was used to study its influence on skin incorporation in this life period as related to UVR‐induced cutaneous alterations, in accordance with previous research protocols regarding generations . The duration of post‐weaning supplementation (90 days) was chosen based on previous studies that assessed the influence of FA on the skin health of rodents .…”

“…Dietary fats constitute an additional known environmental factor that may alter the susceptibility to skin diseases . Trans fatty acids (TFA) are formed industrially with saturated FA when vegetable oils are hardened by hydrogenation, and may be incorporated into membrane lipids following absorption , thereby affecting the physical properties of the cell membrane and the membrane‐bound enzymes.…”