Green can mean money, jealousy, eco-friendliness, or naivety.
And when it comes to diets, green unquestionably signifies "healthy".
While cognitive abilities naturally decline with age, new research suggests that just one daily serving of leafy green vegetables may help preserve memory and thinking skills.
Aside from loads of essential minerals, B vitamins, and vitamins A, C, and K, green veggies brim with beneficial “phytochemicals”.
These include antioxidants such as lutein, zeaxanthin, chlorophyll, and carotene-type compounds.
And cruciferous veggies like broccoli, kale, cress, collard or mustard greens, and Brussels sprouts also provide anti-cancer phytochemicals called isothiocyanates.
Chicago study probes brain effects of leafy greens
Growing evidence suggests that colorful, nutrient-dense vegetables can enhance and preserve memory, thinking capacity, and overall brain health.
The latest findings were reported by researchers at Chicago’s Rush University Medical Center, led by nutritional epidemiologist Martha Clare Morris, Sc.D.
As she said, “There continue to be sharp increases in the percentage of people with dementia as the oldest age groups continue to grow in number. Adding a daily serving of green leafy vegetables to your diet may be a simple way to help promote brain health.”
Findings links greens to younger brain age
The Chicago team's results showed that older adults who ate at least one serving of leafy green vegetables daily scored higher on brain-performance tests than peers who didn’t.
The study involved 960 older adults residing in Chicago-area retirement communities and senior public housing complexes who were already participating in the ongoing Rush Memory and Aging Project, which began in 1997.
All the participants completed diet questionnaires and underwent annual tests designed to measure their cognitive capacities, including thinking and memory.
The average age of the participants was 81 years at the outset of the study, and none showed signs of dementia at the time. The Rush researchers followed the volunteers for an average of 4.7 years.
Overall, the participants’ scores on the thinking and memory tests declined at a rate of 0.08 standardized units per year.
The researchers divided the participants into five groups based on how often they reportedly ate green leafy vegetables.
Then, they compared the cognitive test scores of those who ate the most greens (about 1.3 servings per day) with the scores of those who ate the fewest green (0.1 servings per day).
Encouragingly, the rate of mental decline for those who ate the most leafy greens was much slower.
In fact, as Dr. Morris said, the difference in mental capacity between people who ate lots of greens and those who didn’t was equivalent to being 11 years younger.
Her team credited these benefits to higher intakes of nutrients such as phylloquinone (vitamin K1), lutein, nitrate (which helps keep arteries open), folate (vitamin B9), alpha-tocopherol (vitamin E), and kaempferol (an antioxidant).
The results held true after accounting for other factors that could affect brain health, such as seafood and alcohol consumption, smoking, high blood pressure, obesity, education level, and amounts of physical and cognitive activity.
Of course, as Dr. Morris noted, “The study results do not prove that eating green, leafy vegetables slows brain aging, but it does show an association.”
And because the study focused on older adults — most white — the results may not apply to younger adults and to people of color.
The study was supported by the National Institutes of Health and the USDA Agricultural Research Service.
Dr. Morris and her team have conducted other revealing research into the effects of diet on brain health. For example, see MIND Diet May Cut Alzheimer's Risk, Seafood May Stave Off Memory Loss, Colorful Greens and Veggies Keep Minds Sharp, and Fish Found to Protect People at Risk for Alzheimer's.
Greens also aid eye, heart, metabolic, and immune health
Given their abundant amounts of nutrients and phytochemicals, it’s no surprise that green, leafy vegetables support other aspects of health.
As long ago as 1994, researchers from the Massachusetts Eye and Ear Infirmary found a strong link between higher intake of foods rich in the carotenoids lutein and zeaxanthin and reduced risk for age-related macular degeneration — with the strongest link being to copious consumption of green leafy vegetables.
Those findings have been confirmed in more recent research linking some of the antioxidants that abound in dark leafy greens (lutein, zeaxanthin, and alpha-tocopherol) to reduced risk of cataract formation.
Leafy greens are also rich in fiber and folate (vitamin B9), which help protect against cancer while supporting heart health.
The American Institute for Cancer Research (AICR) says that foods — such as dark leafy greens — containing carotenoids — probably protect against cancers of the mouth, pharynx and larynx.
Further, the AICR says that some lab research shows that the carotenoids in dark green leafy vegetables can curb the growth of lung cancer, stomach cancer, and certain types of breast cancer and skin cancer cells.
And a recent study from Britain’s University of Leicester found the link between eating one serving of leafy greens daily to a 14% lower risk of type 2 diabetes
When it comes to heart health, the folate in green veggies can reduce blood pressure and blood levels of homocysteine and cholesterol. (High levels of homocysteine are associated with increased risk for cardiovascular disease in certain people.)
Clearly, we should all “think green”, and strive for at least one serving of leafy vegetables every day.
Which greens are best?
Joel Fuhrman, M.D., devised a widely used scale called Aggregate Nutrient Density Index or ANDI, which ranks foods according to their concentrations of minerals, vitamins, and phytochemicals.
The highest possible score is 1,000, and the only foods that reach that goal are certain members of the cruciferous vegetable family: Kale, watercress, Swiss chard, mustard greens, turnip greens, and collard greens.
These are their closest competitors on the ANDI point scale:
- Bok Choy: 865
- Napa Cabbage: 714
- Spinach: 707
- Arugula: 604
Of course, many other green veggies score high on the ANDI scale, and it's smart to eat a broad selection, because they offer different mixes of nutrients and phytochemicals.
You'll find a full list of foods and their ANDI scores on Dr. Fuhrman’s website.
Go for the green
Here are a few simple ways to get your leafy greens daily:
- Breakfast: Toss some raw baby kale into your morning smoothie or scrambled eggs.
- Lunch: Enjoy a spinach salad with a sliced hard-boiled egg — which provides even more lutein — and fresh strawberries.
- Dinner: Serve wild salmon over sautéed greens, with a side of broccoli.
To make things easier, steam or sauté a big bunch of greens — adding garlic is a great idea — refrigerate the results, and enjoy them over the next two to four meals.
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