Fish oil, vegetable oil, which are considered “healthy oils“, are not all able to reduce the risk of stroke? From the world’s largest database of fatty acid profiles, experts found that the relationship is quite tortuous.
Lin Xu’s research group from Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, in collaboration with the “China Chronic Diseases Prospective Study” (CKB) research team, published a paper on April 21, 2022 in the internationally renowned journal Eur J Nutr (” A paper was published in the European Journal of Nutrition), through the data of 30 red blood cell membrane fatty acids of 10,563 volunteers in 10 regions of my country, and their associations with the incidence of stroke were mined.
Stroke is the second leading cause of death worldwide after ischemic heart disease. In the Chinese population, the incidence of stroke (adjusted for age) ranks first in the world, and the proportion of hemorrhagic stroke is significantly higher than that in the Western population.
Unhealthy dietary factors, such as lower intake of fruits, vegetables, whole grains and higher sodium intake, play an important role in the pathogenesis of stroke.
Western population studies have found that eating polyunsaturated fatty acids (PUFAs) instead of saturated fatty acids may reduce the risk of stroke. However, in mechanism studies, n-3 and n-6 in PUFA are considered to be two types of fatty acids with opposite physiological roles, and they also compete with each other during their metabolism.
At present, worldwide, the intake level of n-6 PUFA is much higher than that of n-3 PUFA, so their role in health has received more extensive attention.
Compared with traditional dietary questionnaires, blood PUFA levels are more objective and accurate indicators. And, more importantly, due to the long half-life of red blood cells, PUFA levels in red blood cell membranes can reflect longer-term in vivo PUFA levels.
So far, international prospective cohort studies on erythrocyte membrane PUFA levels and stroke risk are limited, especially in Asian populations.
The key deployment project of the Chinese Academy of Sciences “Establishment, characteristics and relationship with diseases of fatty acid profiles of ten thousand people in China” With the support of the CKB research team, the public technology center of the Shanghai Institute of Nutrition and Health (formerly the Institute of Nutritional Sciences) used gas chromatography to quantitatively detect some volunteers who participated in the second repeat survey of the CKB project for 3 years. The red blood cell membrane fatty acid profile of the individual has been established by far the largest database of fatty acid profiles in all countries in the world.
This fatty acid profile database includes 30 red blood cell membrane fatty acid data of 10,563 volunteers from 10 regions in my country.
In this study, associate researcher Sun Liang from Lin Xu’s research team cooperated with the CKB research team to systematically analyze the geographical distribution characteristics of various erythrocyte membrane PUFAs and their relative characteristics. Association with the risk of different subtypes of stroke (eg, ischemic and hemorrhagic stroke).
The research team made the following main findings:
(1) The distribution of various PUFA levels in the 10 regions is very different (Figure 1), for example, 18 of Harbin residents :2n-6 (LA) levels were the highest, while Haikou residents had the highest levels of 20:5n-3 (EPA) and 22:6n-3 (DHA); Gansu residents had the highest levels of 18:3n-3 (ALA) and 22:5n- 3 (DPA) levels were highest, but 20:4n-6 (AA) and DHA were the lowest.
Figure 1. Regional distribution of erythrocyte membrane polyunsaturated fatty acid levels
(2) In n-6 PUFAs, elevated LA levels were significantly associated with both a reduced risk of ischemic stroke and an increased risk of hemorrhagic stroke; while elevated 20:3n-6 levels were associated with ischemic stroke An increased risk of stroke was significantly associated.
(3) Among n-3 PUFAs, EPA showed an inverted U-shaped non-linear relationship with the risk of ischemic stroke, that is, only when the erythrocyte membrane EPA level was higher than 0.70%, its level increased. Higher talent was associated with a reduced risk of ischemic stroke (Figure 2).
Figure 2. Nonlinear relationship between erythrocyte membrane 20:5n-3 levels and ischemic stroke< /span>
Sun Liang introduced that LA mainly comes from vegetable oil, 20:3n-6 is mainly synthesized in the body, and EPA mainly comes from marine fish.
Because the pathogenesis of ischemic stroke and hemorrhagic stroke are different, LA can reduce LDL (low density lipoprotein) and inhibit platelet aggregation, which can reduce the risk of ischemic stroke, but for Hemorrhagic strokes are at increased risk.
She explained that western population studies tend to focus on ischemic stroke, so it is difficult to observe the opposite effect of LA on hemorrhagic stroke and ischemic stroke. In addition, the EPA level of the Chinese population is much lower than that of the Western population, and the protective effect of EPA on the cardiovascular may be masked by the environmental pollutants in seafood, so it may need to be reflected at a relatively high level. “Because our sample size is relatively large, and the level of EPA in the 10 regions is very different, it is only possible to observe the inflection point of its effect on stroke risk.”
In conclusion, this study uses a large sample of The cohort study, for the first time suggests that the distribution characteristics of different types of PUFA in different regions of my country, and that different PUFAs have different significant associations with the risk of stroke (and its subtypes). This study not only improves our understanding of the etiology of stroke, but also provides new evidence for future stroke prevention and control.
Researcher Lin Xu of Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Professor Chen Zhengming of Oxford University are the co-corresponding authors of this paper, and Professor Li Liming of Peking University School of Public Health is the co-senior author of this paper; Chinese Academy of Sciences Associate researcher Sun Liang of Shanghai Institute of Nutrition and Health and associate professor Du Huaidong of Oxford University are the co-first authors of the paper.
Author: Xu Qimin
Picture: pixabay, provided by the research team
Responsible editor: Ren Quan
*Wenhui’s exclusive manuscript, please indicate the source when reprinting.