Saito Morio, Kubo Kazuhiro
National Institute of Health and Nutrition, Tokyo, Japan.
Ann Nutr Metab. 2002;46(5):176-81. doi: 10.1159/000065404.
BACKGROUND/AIMS: In order to clarify an appropriate intake of docosahexaenoic acid (DHA, 22:6n-3), from the viewpoint of safety and physiological efficacy, the potential changes in lipid peroxidation and antioxidant defense in serum and tissues as well as those in serum lipid levels were examined in matured rats at the age of 1 year.
Rats were given the diets containing graded levels of purified DHA (0, 1.0, 3.1 and 8.4% of total energy, en%) for 30 days (control and 1.0, 3.1 and 8.4 en% groups). Lipid peroxides and alpha-tocopherol levels in serum and tissues, and lipid levels in serum were measured.
Serum alpha-tocopherol concentrations in the 3.1 and 8.4 en% groups were significantly lower than those in the control group. Liver lipid peroxide levels assessed using the microsomal conjugated dienes were significantly higher in the 3.1 and 8.4 en% groups than those in the control group, and the chemiluminescence intensity and thiobarbituric acid value were significantly greater in the 8.4 en% group than in the control group. The liver alpha-tocopherol level decreased in response to the increases in lipid peroxide levels, but a significant difference was recognized only in the 8.4 en% group. In the kidney, no changes in lipid peroxide levels were observed, but the alpha-tocopherol level was significantly lower in the 8.4 en% group than in the control group. The levels of all the serum lipids including total cholesterol, HDL-cholesterol, triacylglycerols and phospholipids decreased as the dietary DHA level increased, and total cholesterol and phospholipid concentrations were significantly lower in the 3.1 and 8.4 en% groups than in the control group.
These experimental results suggest that the dietary intake of DHA should not be more than 3 en% in matured rats to avoid the potentially chronic deleterious influences caused by lipid peroxidation in serum and tissues, and that the amelioration of serum lipid levels is recognized in rats fed DHA at 3 en% and above.
背景/目的：为了从安全性和生理功效的角度明确二十二碳六烯酸（DHA，22:6n - 3）的适宜摄入量，对1岁龄的成年大鼠血清和组织中脂质过氧化和抗氧化防御的潜在变化以及血清脂质水平的变化进行了研究。
给大鼠喂食含不同水平纯化DHA（分别占总能量的0%、1.0%、3.1%和8.4%，即en%）的日粮30天（对照组以及1.0 en%、3.1 en%和8.4 en%组）。测定血清和组织中的脂质过氧化物和α - 生育酚水平以及血清脂质水平。
3.1 en%组和8.4 en%组的血清α - 生育酚浓度显著低于对照组。使用微粒体共轭二烯评估的肝脏脂质过氧化物水平在3.1 en%组和8.4 en%组显著高于对照组，且8.4 en%组的化学发光强度和硫代巴比妥酸值显著高于对照组。肝脏α - 生育酚水平随脂质过氧化物水平的升高而降低，但仅在8.4 en%组有显著差异。在肾脏中，未观察到脂质过氧化物水平的变化，但8.4 en%组的α - 生育酚水平显著低于对照组。随着日粮DHA水平的升高，包括总胆固醇、高密度脂蛋白胆固醇、三酰甘油和磷脂在内的所有血清脂质水平均下降，3.1 en%组和8.4 en%组的总胆固醇和磷脂浓度显著低于对照组。
这些实验结果表明，成年大鼠日粮中DHA的摄入量不应超过3 en%，以避免血清和组织中脂质过氧化可能造成的慢性有害影响，并且在喂食3 en%及以上DHA的大鼠中可观察到血清脂质水平的改善。
