The U.S. Soybean Export Council (USSEC) tracks trends with potential to represent global market opportunities for U.S.-grown soy. As consumer definitions of health and wellness evolve, soyfoods may gain additional traction globally. Research on the impact that diet can have on cognitive function is one emerging area of interest.
This is part one of a two-part series.
Diet is known to affect many chronic diseases, so it is not surprising that scientists have studied its impact on cognitive function. Diet and nutrition can have an effect on aging brains, memory, mental health and other brain-related functions. Soy-related research pertaining to cognitive function goes back 20 years.[1]
The fact that soybeans are a rich source of isoflavones has motivated scientists to study the effects of soyfoods on the brain. Isoflavones are naturally occurring compounds. They are different from the hormone estrogen, but they have some properties in common.[2]
Consumer perceptions of the importance of mental wellbeing are evolving. More than 60 percent of global consumers now rank mental health as the primary indicator of good health, ahead of the other four top factors —feeling good, getting enough sleep, absence of disease and maintaining a healthy weight.[3] The pandemic has motivated global consumers to place more emphasis on health and wellness in their daily lives. For example, 51 percent of UK consumers have used some sort of health technology, including nutrition apps, in their quest for health.[4] Increased interest in wellness and nutrition creates opportunities for soyfoods as more is learned about their possible brain health benefits. And, due to the level of consumer interest, the global brain health supplements market is expected to reach $13.38 billion by 2028.[5]
The Effects of Soy on Memory: The first clinical study to evaluate the effect of soy on cognition was published in 2001.[6] This 10-week trial found that soyfoods led to significant improvements in both short-term and long-term memory and in mental flexibility in healthy men and women. A few years later, research by the same investigative team found that in older women, soybean isoflavones improved short-term, but not long-term, memory.[7]
Soy and Cognitive Function: Cognitive health is one of the few health concerns that worries consumers of all ages.[8] Over the past two decades, much effort has gone into determining whether soy improves cognitive function. This effort has produced inconsistent findings, as some studies have shown benefits while others have not.
However, in 2015, a statistical analysis of 10 placebo-controlled randomized trials involving over 1,000 postmenopausal women suggests isoflavones favorably affect overall cognitive function and visual memory.[9] Two years later, another analysis reached a similar conclusion.[10] And finally, last year, an analysis of 16 clinical studies involving 1,386 participants with a mean age of 60, concluded that soy isoflavones may improve cognitive function in adults.[11]
Another recent notable study involved older adults from Japan, a country where soyfoods are commonly consumed. The study reported that women who consumed above average amounts of soyfoods daily were about were about 50 percent less likely to become cognitively impaired although no such benefits were reported in men.[12]
Soyfoods made from U.S.-grown soybeans provide a reliable supply of high-quality protein, healthy fat and a variety of vitamins and minerals. Such attributes provide plenty of reasons for global consumers to add soyfoods to the diet. The evidence, while not definitive, does suggest that improving cognitive function might be one of them. A good recommendation is to strive for consuming two servings per day. One serving of soyfoods equals a cup of soymilk, an ounce of soynuts or one-half cup of tofu.
References
[1] File SE, Jarrett N, Fluck E, et al. Eating soya improves human memory. Psychopharmacology (Berl). 2001;157:430-6.
[2] Harvard T.H. Chan School of Public Health, Straight Talk About Soy. The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/soy/
[3] Westbrook, G and Angus, A. Euromonitor International, Top 10 global consumer trends 2021, p. 32.
[4] Mintel Global Consumer Trends, 2021.
[5] Grand View Research, The Global Brain Health Market, January, 2021.
[6] File SE, Jarrett N, Fluck E, et al. Eating soya improves human memory. Psychopharmacology (Berl). 2001;157:430-6.
[7] File SE, Hartley DE, Elsabagh S, et al. Cognitive improvement after 6 weeks of soy supplements in postmenopausal women is limited to frontal lobe function. Menopause. 2005;12:193-201.
[8] Euromonitor, 2020 Health and Nutrition Survey.
[9] Cheng, PF, Chen JJ, Zhou XY, et al. Do Soy isoflavones improve cognitive function in postmenopausal women? A meta-analysis. Menopause. 2015; 22:198-200.
[10] Thaung Zaw JJ, Howe PRC, Wong RHX. Does phytoestrogen supplementation improve cognition in humans? A systemic review. Ann N Y Acad Sci. 2017; 1403: 150-63
[11] Chendi Cui, Rahel L Birru, Beth E. Snitz, et al. Effects of soy isoflavones on cognitive function; a systematic review and meta-analysis of randomized control trials. Nut Rev, 2020 Feb; 78(2): 134–144. Published online 2019 Sep 4. doi: 10.1093/nutrit/nuz050
[12] Nakamoto, M.; Otsuka, R.; Nishita, Y.; Tange, C.; Tomida, M.; Kato, Y.; Imai, T.; Sakai, T.; Ando, F., and Shimokata, H.; Soy food and isoflavone intake reduces the risk of cognitive impairment in elderly Japanese women. Eur J Clin Nutr. 2018, 72, 1458-1462.
