One serving of leafy greens a day may slow brain aging by 11 years
While cognitive abilities naturally decline with age, eating one serving of leafy green vegetables a day may aid in preserving memory and thinking skills as a person grows older, according to a study by researchers at Rush University Medical Center in Chicago. The study results were published in the December 20, issue of Neurology, the medical journal of the American Academy of Neurology.
"Adding a daily serving of green leafy vegetables to your diet may be a simple way to help promote brain health," said study author Martha Clare Morris, ScD, a nutritional epidemiologist at Rush. "There continues to be sharp increases in the percentage of people with dementia as the oldest age groups continue to grow in number. Effective strategies to prevent dementia are critically needed."
The study results suggest that people who ate one serving of green, leafy vegetables had a slower rate of decline on tests of memory and thinking skills than people who rarely or never ate them. The study results also suggest that older adults who ate at least one serving of leafy green vegetables showed an equivalent of being 11 years younger cognitively.
960 older adults completed food questionnaires and received annual cognitive assessments
The study enlisted volunteers already participating in the ongoing Rush Memory and Aging Project, which began in 1997 among residents of Chicago-area retirement communities and senior public housing complexes. A "food frequency questionnaire" was added from 2004 to February 2013, which 1,068 participants completed. Of them, 960 also received at least two cognitive assessments for the analyses of cognitive change.
This study involved these 960 people, who at the study start were an average age of 81 years old and did not have dementia. They had their thinking and memory skills tested every year and were followed for an average of 4.7 years. The participants also completed the food frequency questionnaire, which assessed how often and how many half-cup servings they ate of either spinach; kale/collards/greens; or a one-cup serving of lettuce/salad.
The study divided the participants into five groups based on how often they ate green leafy vegetables, and compared the cognitive assessments of those who ate the most (an average of about 1.3 servings per day) and those who ate the least (0.1 servings per day).
Overall, the participants' scores on the thinking and memory tests declined at a rate of 0.08 standardized units per year. Over 10 years of follow-up, the rate of decline for those who ate the most leafy greens was slower by 0.05 standardized units per year than the rate for those who ate the least leafy greens. This difference was equivalent to being 11 years younger in age, according to Morris.
More research needed in younger and minority populations
The results remained valid after accounting for other factors that could affect brain health, such as seafood and alcohol consumption, smoking, high blood pressure, obesity, education level and amount of physical and cognitive activities.
"The study results do not prove that eating green, leafy vegetables slows brain aging, but it does show an association," Morris said. "The study cannot rule out other possible reasons for the link."
Because the study focused on older adults with the majority of participants being white, the results may not apply to younger adults and to people of color. The results need to be confirmed by other investigators in different populations and through randomized trials to establish a cause-and-effect relationship between the eating leafy greens and reductions in the incidence of cognitive decline, Morris said.
Kileo kimoja cha majani ya kijani kibichi kila siku kinaweza kupunguza kuzeeka kwa ubongo kwa miaka 11, kulingana na utafiti uliofanywa na watafiti wa Chuo Kikuu cha Rush Medical Center huko Chicago. Matokeo ya utafiti huo yamechapishwa katika toleo la Desemba 20 la Neurology, jarida la matibabu la American Academy of Neurology. "Kuongeza mchanganyiko wa mboga za majani ya kijani kwenye mlo wako inaweza kuwa njia rahisi ya kusaidia kukuza afya ya ubongo, ""mwandishi wa utafiti Martha Clare Morris, Sc.D., mtaalamu wa magonjwa ya magonjwa ya afya katika Rush, alisema." "Kunaendelea kuwa na ongezeko kubwa katika asilimia ya watu wenye ugonjwa wa akili huku vikundi vya umri wa zamani vikiongezeka kwa idadi. Mkakati wenye matokeo wa kuzuia ugonjwa wa akili unahitajika sana". Matokeo ya utafiti huo yanaonyesha kuwa watu waliokula kipimo kimoja cha mboga za majani ya kijani walikuwa na kiwango cha chini cha kupungua kwa vipimo vya kumbukumbu na uwezo wa kufikiri kuliko watu ambao walikula mara chache au kamwe. Matokeo ya utafiti huo pia yanaonyesha kwamba watu wazima walio na umri mkubwa ambao walikula angalau kipimo kimoja cha mboga za majani ya kijani walionyesha kuwa na umri mdogo wa miaka 11 kwa akili. "Wanaume na wanawake 960 waliokamilisha maswali ya chakula na kupokea tathmini za kila mwaka za utambuzi, utafiti huo ulijumuisha wajitoleaji ambao tayari wanashiriki katika ""Rush Memory and Aging Project"" ambayo ilianza mnamo 1997 kati ya wakazi wa jamii za uzeeni za eneo la Chicago na majengo ya umma ya wazee." "Kulingana na uchunguzi wa ""Food Frequency Questionnaire"" uliofanywa na utafiti huo, watu 1,068 waliwahi kujaza maswali hayo." Zaidi ya watu 960 walipata angalau tathmini mbili za utambuzi wa mabadiliko ya utambuzi. Utafiti huo ulihusisha watu 960 ambao walianza na umri wa wastani wa miaka 81 na hawakuwa na dementia. Wanafunzi hao walipimwa uwezo wao wa kufikiri na kukumbuka kila mwaka na kufuatiliwa kwa wastani wa miaka 4.7. Washiriki pia walijaza maswali ya mara kwa mara ya chakula, ambayo ilichunguza ni mara ngapi na ni vikombe vingapi walikula spinach, kale, collard, au kikombe kimoja cha saladi. Uchunguzi huo uligawanya washiriki katika vikundi vitano kulingana na mara nyingi walikula mboga za majani ya kijani, na kulinganisha tathmini za utambuzi wa wale waliokula zaidi (kwa wastani wa vipimo vya 1.3 kwa siku) na wale waliokula kidogo (vipimo vya 0.1 kwa siku). Kwa ujumla, alama za washiriki katika vipimo vya kufikiri na kumbukumbu zilipungua kwa kiwango cha 0.08 ya vitengo vya kawaida kwa mwaka. Katika miaka 10 ya kufuatilia, kiwango cha kupungua kwa wale waliokula mboga nyingi za majani kilikuwa polepole kwa vitengo 0.05 kwa mwaka kuliko kiwango cha wale waliokula mboga chache. Tofauti hiyo ilifanana na kuwa na umri mdogo kwa miaka 11, kulingana na Morris. Matokeo ya utafiti huo yalithibitika kuwa sahihi baada ya kuzingatia mambo mengine ambayo yanaweza kuathiri afya ya ubongo kama vile chakula cha baharini na matumizi ya pombe, uvutaji sigara, shinikizo la damu, unene wa kupita kiasi, kiwango cha elimu na kiasi cha shughuli za kimwili na za utambuzi. "Matokeo ya utafiti huo hayaonyeshi kwamba kula mboga za majani na kijani hupunguza uchanga wa ubongo, lakini yanaonyesha uhusiano huo", Morris alisema. "Utafiti huo hauwezi kukataa sababu nyingine zinazoweza kusababisha uhusiano huo". Kwa sababu utafiti huo ulizingatia watu wazima wenye umri mkubwa na wengi wa washiriki walikuwa wazungu, matokeo hayawezi kutumika kwa watu wazima wadogo na watu wa rangi. "Hatua hiyo inahitaji kuthibitishwa na watafiti wengine katika idadi tofauti ya watu na kupitia majaribio ya nasibu ili kuanzisha uhusiano wa sababu na athari kati ya kula majani ya kijani na kupunguzwa kwa matukio ya kupungua kwa utambuzi, ""alisema Morris."