The gut contains trillions of microorganisms collectively called the gut microbiota. These microorganisms are known to play an important role in maintaining human health. However, there is not much known about the health effects associated with changes in gut microbiota that come with age. As a person gets older, the diversity of the gut microbiota declines.
In the study, the researchers wanted to better understand how gut microbiota changes influence age-related cognitive decline. To do so, they fed 24-month old mice, which is equivalent to the age of people between 56 and 69 years, with allyl sulfide orally. Then, they compared these mice with four- and 24-month-old mice which did not receive the dietary allyl sulfide supplement.
The researchers saw that the older mice that received the garlic compound exhibited better long- and short-term memory, as well as healthier gut bacteria, compared with the older mice that did not receive the treatment. The two-year-old mice that did not receive the garlic compound also had impaired spatial memory.
In additional experiments, the researchers found that the reduced gene expression of neuronal-derived natriuretic factor (NDNF) in the brain was likely responsible for the cognitive decline. This gene, which was recently discovered by the researchers, is needed for long-term and short-term memory combination.
Moreover, the team found that mice that received allyl sulfide exhibited higher levels of NDNF gene expression. Recombinant-NDNF protein therapy in the brain also restored the cognitive function of the older mice that did not receive the garlic compound. Moreover, they found that the administration of allyl sulfide produced a hydrogen sulfide gas, which prevents inflammation in the intestines, in the gut lumen.
Taken together, the findings indicated that the intake of the garlic compound could enhance memory consolidation by restoring gut bacteria. The team continues to conduct experiments to better understand the relationship between the gut microbiota and cognitive decline. They also plan to look at whether garlic could be used as a treatment for age-related cognitive problems, such as Alzheimer's disease and Parkinson's disease. They presented the current study’s findings at the American Physiological Society's annual meeting held in Orlando, Florida.
For thousands of years, garlic has been used both for culinary and medicinal purposes. And over the years, scientists have uncovered and proven its health benefits, especially its benefits for the brain.
For one, garlic may help prevent brain cancer. It contains another compound called dilly trisulfide (DATS), which plays a role in reducing tumor growth in individuals with glioblastoma, the deadliest form of brain tumor. In a study published in the Journal of Neuro-Oncology, the compound effectively prevented tumor progression and induced apoptosis or cell death in active human glioblastoma, without harming the liver.
Garlic can also improve blood flow to the brain by preventing blood clot formation. Blood clots are masses that occur when liquid blood hardens. A blood clot can block an artery or vein in the heart, which may also affect the neck or brain and lead to stroke. Eating garlic can help because it is an effective blood thinner, which works like aspirin, and can help regulate blood circulation.
Aside from garlic, there are many other spices that can boost brain function. These include turmeric, oregano, thyme, rosemary, sage, black pepper, cinnamon, cloves, nutmeg, and holy basil.