In the context of global ageing, the prevention of cognitive decline and dementia has become a key public health goal. Although lifestyle factors are known to be closely associated with cognitive health, there is a need for a better understanding of how midlife eating habits affect the risk of dementia in later life.
Polyunsaturated fatty acids (PUFAs)
PUFAs are an important class of fatty acids, which are essential for good health, mainly including n-3 and n-6, but currently more attention is paid to n-3 intake. n-3 PUFAs are commonly found in fish (especially deep-sea fish such as salmon and mackerel), flaxseeds, and walnuts and are beneficial for heart health and brain function.
In recent years, a research team has investigated the relationship between fish consumption and n-3 PUFAs intake and the risk of cognitive impairment (dementia and mild cognitive impairment) in later life in middle-aged people. A cohort study of 1,127 middle-aged participants was conducted using food frequency data from 1995-2000 combined with cognitive status assessments from 2014 to 2015. The association between fish and other PUFA intake and dementia risk was analysed by logistic regression model, and a variety of confounding factors were adjusted.
Studies have revealed that higher fish consumption in middle age is associated with a lower risk of dementia. Specifically, the three groups with higher fish intake showed a significantly lower risk of dementia. At the same time, high intake of specific n-3 PUFAs, such as EPA, DHA, and DPA, was also associated with a reduced risk of dementia.
These foods are rich in polyunsaturated fatty acids, so keep them in mind
Polyunsaturated fatty acids (PUFAs) are essential fatty acids that fall into two main groups: the n-3 (omega-3) series and the n-6 (omega-6) series, which play an important role in maintaining cell function, promoting heart health, and brain development. It is important to note that while n-6 PUFAs are necessary, the ratio of n-6 to n-3 in modern diets is often excessive, and a balanced intake is recommended to promote health. Therefore, increasing the intake of foods from N-3 sources while controlling the intake of N-6 fatty acids is the key to optimizing the proportion of fatty acids in the diet.
Foods rich in n-3 PUFAs (increase intake in moderation):
1. Fish and Seafood:
- Deep-sea fish are particularly rich in long-chain n-3 PUFAs EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), such as salmon, salmon, mackerel, herring, sardines and cod liver.
2. Plant Sources:
- Flaxseed is an excellent source of α-linolenic acid (the basal form of the ALA, n-3 family) that can be converted into EPA and DHA in the body, albeit with limited conversion efficiency.
- Other foods rich in ALA include chia seeds, perilla seeds, walnuts, soy products, and leafy greens (spinach, mustard greens, etc.).
Foods rich in n-6 PUFAs (relatively reduced intake):
1. Vegetable oil:
- Most vegetable oils are rich in N-6 fatty acids, especially corn oil, sunflower oil, soybean oil, and safflower oil.
- Peanut oil and cottonseed oil also contain higher levels of n-6 PUFAs.
2. Nuts & Seeds:
- Sunflower seeds, sesame seeds, pumpkin seeds, and many nuts (with the exception of walnuts, which are rich in n-3) contain higher amounts of n-6 PUFAs.
- Almonds, hazelnuts, and pistachios are also good sources of N-6.
3. Meat & Dairy:
- Livestock and poultry meats (especially those with high levels of corn and soybeans in feed) and some dairy products are high in N-6 fatty acids because animals convert N-6 fatty acids from plants into fat in their bodies.
参考文献——Nozaki S, Sawada N, Matsuoka YJ, Shikimoto R, Mimura M, Tsugane S. Association Between Dietary Fish and PUFA Intake in Midlife and Dementia in Later Life: The JPHC Saku Mental Health Study. J Alzheimers Dis. 2021; 79(3):1091-1104. doi: 10.3233/JAD-191313. PMID: 33386799.