The following models were tested: 1 age and gender; 2 model 1 plus education, urbanization, duration of follow-up, smoking, alcohol intake, physical activity, composite cognitive Z-score, diabetes, BMI, systolic, and diastolic blood pressure at baseline; 3 model 2 plus intake of energy, sodium, potassium, fat, and fiber.

We also calculated the linear trend by assigning participants the median intake within each quintile of the percentage of energy from dietary protein for each food source. Logistic regression models were used to examine whether protein intakes from different food sources were associated with cognitive decline.

Moderation analysis was used to test whether the association between protein intake and cognitive decline depended on other important factors. Moderation analysis was conducted to examine whether the association of plant and animal protein intake with cognitive decline was modified by age, gender, education, urbanization, and follow-up duration.

Sensitivity analysis was conducted to examine whether the association of the average annual protein intake of surveys completed before the first cognitive assessment with changes in cognitive Z-scores. Analyses were performed using SAS version 9.

and all P -values were two-sided. A total of 3, participants Individuals with a higher plant protein intake were more likely to have lower education, live in rural areas, currently smoke, and have higher physical and occupation activity levels compared to those with a lower plant protein intake.

An inverse association between plant protein intake and composite cognitive Z-scores at baseline was observed Tables 1 , 2. In contrast, higher animal protein intake was associated with lower energy intake, lower fiber intake, and higher sodium intake.

There was a positive association between the animal protein intake and the composite cognitive Z-score at baseline Supplementary Table 1. Participants consumed The main plant sources of protein were grains 8. The main animal sources of protein included red meat 1. During a median follow-up of 9 2—18 years, composite cognitive Z-score declined by 0.

The prevalence of cognitive decline defined by the cognitive change below mean minus 1. Protein intake from other plant foods was not significantly associated with change in composite cognitive Z-score. Conversely, animal protein intake was positively associated with change in composite cognitive Z-score.

The corresponding number for protein intake from poultry and fish was 0. Protein intake from red meat, dairy, or eggs was positively associated with change in composite cognitive Z-score before but not after adjustment for the intake of energy, fiber, sodium, potassium, and fat Table 3.

Table 3. Animal protein intake was positively associated with change in memory Z-score before but not after adjustment for confounders Supplementary Table 2. An inverse association between plant protein intake and change in subtraction Z-score was found before but not after adjustment for confounders.

This was consistent with cognitive decline as defined by cognitive change below mean minus 1. quintile 1 of plant protein intake: 1. Animal protein intake was not significantly associated with cognitive decline Supplementary Table 5. Table 5. Sensitivity analysis showed the average annual plant protein intake reported in surveys completed before the first cognitive assessment was inversely associated with change in composite cognitive Z-score during follow-up Supplementary Table 6.

This longitudinal study of community-dwelling older Chinese adults demonstrated that lower plant protein but higher animal protein intake was associated with a lower risk of cognitive decline.

We found higher plant protein intake was associated with greater cognitive decline. Our findings are supported by some studies from Europe demonstrating a positive association between plant protein intake and diabetes The harmful effect of high plant protein intake may be attributed to the deficiency of micronutrients in plant-based diets including vitamin B12 and iron, which are associated with a higher risk of cognitive impairment 26 — Furthermore, plant-based proteins have relatively low essential amino acids and leucine contents or even lack one or more of the essential amino acids when compared with animal-based proteins, such that, a higher plant protein intake is less likely to increase lean and skeletal muscle mass This may explain the inverse association between plant protein intake was associated and change in cognition.

Higher protein intake from grains was independently associated with accelerated cognitive decline. This may be due to the fact that grains contain relatively low quantities of essential amino acid lysine, of which lower intake may increase the risk of hypertension, diabetes and obesity 30 , 31 resulting in cognitive decline.

We found an inverse association between animal protein intake and cognitive decline. Our findings are also consistent with some studies of Japanese and Chinese populations demonstrating that animal protein intake was inversely associated with blood pressure 33 , Animal proteins usually contain all essential amino acids, and therefore may consist of optimal amino acid composition resulting in better metabolic health A recent longitudinal study demonstrates that an adequate methionine mainly from animal foods status may decrease the risk of dementia and brain atrophy We also found an inverse association between poultry protein intake and the risk of cognitive decline.

Our findings are supported by a prospective study demonstrating that higher poultry intake was associated with less cognitive decline over 6 years in older Swedish adults 7.

An optimal amino acid composition of dietary protein intake may help optimize amino acid metabolism and protect against dementia risks including obesity, diabetes, hypertension, and stroke A cross-sectional study of Chinese adults found that a higher total protein intake was associated with a higher likelihood of mild cognitive impairment Likely, we found higher total protein intake was associated with accelerated cognitive decline.

Notably, animal sources accounted for only Meanwhile, plant protein intake was inversely but animal protein intake was positively associated with change in composite cognitive Z-score suggesting the inverse association between total protein intake and cognition was driven by plant protein in our study.

This indicates that increasing the proportion of animal protein in populations with plant dominant diets may help protect against cognitive decline. A recent study of US women and men demonstrated that higher plant protein intake and lower animal protein intake was associated with lower likelihood of cognitive decline 13 , but other studies showed that specific protein food sources were not significantly associated with cognitive function The conflicting findings between our study and Yeh et al.

may be due to the fact that the plant foods are dominant in our population, but animal foods are dominant in the US population. To our knowledge, this is the first longitudinal study to examine the association between protein intakes from different food sources with cognitive decline.

Our study has several limitations. First, cognitive assessment was conducted in a subgroup of the CHNS cohort, which limits the generalization of our findings to the whole population in China. Second, our study was conducted in a population with plant food dominant diets, therefore, more longitudinal studies in populations with animal food dominant diets are needed to warrant our findings.

Finally, the wide range of follow-up in our study might influence associations between protein intake and cognition.

However, the results did not substantially change after adjusting for follow-up and the follow-up did not mediate the association, suggesting our findings are independent of the follow-up duration. A relatively high proportion of animal protein in population with plant dominant diets may be protective of cognitive decline.

RG, ZY, and WY conceived and designed the study. RG, WD, and YZ conducted data analysis and drafted the initial manuscript.

ZY, WY, and FZ made critical revision of the manuscript for important intellectual content. All authors read the manuscript and approved the final draft. This research uses data from China Health and Nutrition Survey CHNS.

We thank the National Institute for Nutrition and Health, China Center for Disease Control and Prevention, Carolina Population Center P2C HD and T32 HD , the University of North Carolina at Chapel Hill, the NIH RHD, DK, R24 HD, and RHD and the NIH Fogarty International Center D43 TW and D43 TW for financial support for the CHNS data collection and analysis files from to and future surveys, and the China-Japan Friendship Hospital, Ministry of Health for support for CHNS , Chinese National Human Genome Center at Shanghai since , and Beijing Municipal Center for Disease Prevention and Control since The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers.

Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher. BMI, body mass index; CHNS, china health and nutrition survey; CI, confidence interval; MET, metabolic equivalent of task; OR, odds ratio; SD, standard deviation.

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There is risk that folic acid administered to those with B 12 deficiency may mask anemic symptoms without solving the issue at hand. In this case, people would still be at risk for neurological deficits associated with B 12 deficiency-related anemia, which are not associated with anemia related to folate deficiency.

Vitamin A is an essential nutrient for mammals which takes form in either retinol or the provitamin beta-Carotene. It helps regulation of cell division, cell function, genetic regulation, helps enhance the immune system, and is required for brain function, chemical balance, growth and development of the central nervous system and vision.

Oxygen transportation, DNA synthesis, myelin synthesis, oxidative phosphorylation, and neurotransmitter synthesis and metabolism are all biological processes that require iron; however, an iron imbalance can result in neurotoxicity causing oxidation and modification of lipids, proteins, carbohydrates, and DNA.

Iron is involved with the development and functioning of different neurotransmitter systems and large iron quantities are required for the myelination of white brain matter. Abnormal myelination of white matter due to iron deficiency during development may be related to the onset of psychological disorders in adolescents.

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Confabulation Cryptomnesia Hindsight bias Imagination inflation Memory biases Memory conformity Misattribution of memory Misinformation effect Source-monitoring error. Deese—Roediger—McDermott paradigm False memory syndrome Memory implantation Lost in the mall technique Recovered-memory therapy.