Ever wondered why onion is an ingredient for soups to enhance taste and flavour? What about onion for garnishing suya or boiled rice? While onions may bring a tear to the eye and delight to the taste buds, surprisingly, experts say its daily intake from adulthood can help to improve memory in old age.
In a new study, researchers in Japan found that the intake of quercetin-rich onions improves cognitive function and reduces cognitive decline in elderly people.
Cognition encompasses processes such as knowledge, attention, memory and working memory, judgment and evaluation, reasoning and “computation”, problem solving and decision making, comprehension and production of language.
The study, which evaluated the effects of quercetin-rich onions on cognitive function in 50 healthy adults, might be of importance in the fight against brain diseases such as Alzheimer’s and Parkinson’s.
Alzheimer’s disease is a form of dementia that causes problems with memory, behaviour and thinking, and gradually worsens over time. While there is no known therapy available to prevent or treat Alzheimer’s, research has recognised that lifestyle modifications, including exercise and diet, are important for preventing the early stage of the disease.
The study involved 25 males and 25 females, aged between 65 and 84 years that had a family member to support them by also consuming the test food, to maintain a diary and to manage their physical condition.
Aside blood tests, questionnaire was used to evaluate their registration, attention and calculation, recall, language, and the ability to follow simple commands and orientation.
For the short-term memory test, the subject was first asked to memorise 10 words and to write them down immediately (immediate memory), then approximately 10 minutes later, the subject had to recall the same words to write them again (short-term memory).
The researchers, according to the study’s findings, suggested that the consumption of quercetin-rich onions improves cognitive function directly and indirectly by suppressing risk factors for dementia such as hyperglycemia (high blood sugar level).
In the 2017 journal, Functional Foods in Health and Disease, they said “Although we demonstrated the effect of quercetin-rich onions on subjects of a particular age group, our results suggested that the intervention of dietary food is required at an early stage to improve cognitive function.”
Nonetheless, researchers say that its consumption also has minimal unfavourable effects.
Previously, experts have also said that supplementing the diet with onion and extracts from the vegetable may protect the brain from additional damage linked to stroke.
The 2012 findings according to journal Nutrition suggests that onion extract may be a beneficial nutrient for the prevention of ischemic [blood-brain barrier] damage, and that the underlying mechanisms may include, at least in part, its antioxidant effects.
Moreover, food experts had said that onions is one of the richest and most readily available sources of sulphur-containing compounds which have been shown to slow down the deterioration of memory usually associated with ageing.
In addition, onion extract has also been shown to maintain the hippocampus, a part of the brain that is involved in processing emotions as well as memory.
However onions that are over-cooked may lose their memory-helping properties. They should instead be cooked on a low heat.
Onions have an amazing array of medicinal benefits and are high in vitamin C, folic acid, biotin, chromium, and calcium. This rich source of quercitin has been shown to lower cholesterol, blood pressure, and triglycerides as well as help to significantly strengthen the immune system, brain, and nervous system.
Moreover, Drs Elufioye Taiwo and Hameed Halimah, both researchers at the University of Ibadan, said Morinda lucida and Peltophorum pterocarpum are brain function enhancer, too.
Leaves of Peltophorum pterocarpum and Morinda lucida are commonly found in recipes used as memory enhancer or anti-ageing in Nigeria ethno-medicine.
The experts, who observed that these plants can improve the memory of the animals in a dose-dependent manner, however said that Peltophorum pterocarpum does it better.
Also, a meta-analysis published in the October 2013 issue of Annals of Neurology showed that high adherence to a healthful dietary pattern, such as the Mediterranean diet, may be beneficial in the prevention of various conditions linked to the ageing brain, including cognitive decline, depression, and stroke.
In general, consuming a diet with differently coloured foods can help to take care of the brain functioning for a longer period of time. Such food items include broccoli, grapes and eggplant, which are also rich in both quercetin and anthocyanin.