Broccoli is a member of the Brassica oleracea family of plants, closely related to other ‘sprouting’ vegetables like brussels sprouts, cabbage, cauliflower and kale. While most commonly green, the flowering buds of broccoli can also be purple in color. Interestingly, broccoli is a relatively new crop to North America, first grown in the late 1920s. However, due to its high nutrient content, broccoli has become a popular and widely available health food across Canada.
One cup of raw broccoli clocks in at just 31 calories and contains more than 10% of the recommended daily intake of fibre, making it an excellent choice for those looking to maintain a healthy diet and support digestive health.
In addition to its high fiber content, broccoli is high in antioxidants like vitamin C, flavonoids, carotenoids which help combat oxidative stress, reduce inflammation and support the immune system to fight off infections.
Two of the carotenoids, lutein and zeaxanthin, found in broccoli are beneficial for both visual and cognitive health. They help protect the retina, a thin layer of tissue at the back of the eye, from inflammation and damage. Despite its location, the retina is considered an extension of the brain and central nervous system. It communicates directly with the brain by converting light that enters the eye into neural signals that are sent to the occipital cortex of the brain – a region at the back of the brain responsible for visual processing. Here, the signals are processed and interpreted, allowing us to understand and interact with the world around us.
Carotenoids help maintain the structural integrity and function of the cells in the retina and have been reliably demonstrated to protect against vision loss. Published in the Archives of Ophthalmology in 2001, the Age-Related Eye Disease Study (AREDS) investigated the impacts of high-dose carotenoid supplementation on vision loss in older adults. Age-related macular degeneration is a leading cause of visual impairment as we age.
The AREDS trial found that amongst individuals with a high risk of developing macular degeneration – carotenoid-containing supplements were associated with a 25% lower risk in developing macular degeneration and had significant benefits on preservation of vision.
More recently, a team based out of the University of Georgia’s Department of Psychology have demonstrated the benefits of carotenoid on cognitive function in older adults. Published in the Journal of the International Neuropsychological Society in 2016, the authors measured levels of two distinct carotenoids – lutein and zeaxanthin – in a group of adults above the age of 65. The participants were tested on their ability to learn and recall patterns of words before undergoing a series of imaging tests measuring blood flow in key brain regions responsible for memory and learning.
The authors found that carotenoid levels correlated with both blood flow to these brain regions as well as with improved scores on the cognitive function tests. They hypothesized that the carotenoid levels might improve the efficiency by which brain cells communicate with one another – allowing for more efficient storage and retrieval of memories.
One particular carotenoid, lutein, is emerging as an influential nutrient on brain health that may help to slow brain aging.
Unlike other carotenoids that are not able to be taken up by our brain cells, lutein readily crosses the brain’s protective barrier. In the brain, lutein serves as a potent antioxidant and anti-inflammatory agent. In a large study amongst 13,000 women in the United States, it was found that women who reported the highest consumption of cruciferous green vegetables rich in lutein (like broccoli, spinach, or kale) experienced less cognitive decline when compared to women who ate fewer. This was a significant difference – as this subset of women had a ‘brain age’ that was 1-2 years younger than their counterparts.
Broccoli offers several benefits for brain health due to its rich nutritional content, including vitamins, carotenoids and antioxidants. In addition to the general health benefits and source of fibre that broccoli provides, the research clearly suggests that leafy green vegetables may provide protection against visual and cognitive decline. When incorporated into a healthy diet, these cruciferous vegetables can provide a tasty way to contribute to protect against neurodegenerative diseases and contribute to overall wellbeing!