Remembering to eat foods high in lignans, like broccoli, flax and berries is important for keeping your memory sharp. Several small studies have suggested that phytoestrogens from plants can play a role in maintaining mental abilities, and now two larger studies support those claims.
Lignans are polyphenols found in plants such as seeds, whole grains, legumes (such as soy), fruits and vegetables. Flaxseed also has a high amount of lignans. They are part of a family of phytochemicals called phytoestrogens. They are associated with a lower risk of heart disease, but the studies on reducing risk of various cancers can be conflicting. Read more about lignans here.
In the first study the dietary intake of phytoestrogens over the previous year was determined for 403 postmenopausal women.
Cognitive function, which mainly involves memory and mental abilities, was determined using a questionnaire called the “mini mental state exam.” Decreased scores on this test are associated with Alzheimer’s disease and other age-associated memory problems.
Analysis of the data showed that higher dietary intake of lignans (but not isoflavones) was associated with better cognitive function in postmenopausal women.
The group who ate more lignans had a 49 percent higher rate of intact cognition, whereas the isoflavone group had only a 12 percent higher rate of intact cognition. This effect was more pronounced in women with a longer postmenopausal time span (20 to 30 years).
A more recent study looked at ingestion of several antioxidants including vitamin C, vitamin E, β-carotene, lutein, flavonoids and lignans. This larger, 5-year study involving 2613 persons aged 43-70 year at baseline again showed lignans, much more so than any of the other antioxidant group stood out as improving cognition at middle age.
Phytoestrogens found in plants have a chemical structure similar to that of the hormone estrogen, allowing them to have some similar effects in a woman’s body. A number of mechanisms are proposed for the action of phytoestrogens on the ability to think clearly. These include the ability of phytoestrogens to promote the health of the blood vessels, to act as antioxidants and to interfere with signalling mechanisms within the cell. Among other things, improving mental capacity is one reason why some women choose estrogen replacement therapy. Increasing dietary consumption of lignans may be sufficient for this purpose.
Higher Dietary Intake of Lignans is Associated withBetter Cognitive Performance in Postmenopausal Women. Franco, O.H., et al. The Journal of Nutrition. 135:1190-1195, 2005.
Diet and cognitive decline at middle age: the role of antioxidants. Nooyens AC, Milder IE, van Gelder BM, Bueno-de-Mesquita HB, van Boxtel MP, Verschuren WM, Br J Nutr. 2015 May 14;113(9):1410-7. doi: 10.1017/S0007114515000720. Epub 2015 Apr 8.