Scientists Have Found a New, Healthier Way to Cook Broccoli

SIGNE DEAN

8 FEB 2018

Lately, broccoli has been gaining a reputation as an excellent vegetable due to its high levels of a particularly beneficial compound called sulforaphane.

With some early-stage studies showing how this compound plays a role in blood sugar control and potentially even has anti-cancer benefits, it’s no wonder that broccoli pills are on the rise.

But a 2011 study has shown that eating the whole vegetable gets you more sulforaphane than taking a supplement – so a team of Chinese researchers has been on the case of finding the best way to cook broccoli.

They have a clear winner – but it’s a hard sell if you have better things to do.

The interesting part is that sulforaphane doesn’t just sit there in the broccoli florets, ready to be consumed. Instead, the vegetable contains several compounds called glucosinolates.

It also contains the enzyme myrosinase, which plants have evolved for defending themselves against herbivores. Through what’s known as ‘myrosinase activity’, the glucosinolates get transformed into sulforaphane, which is what we want.

To kick myrosinase activity into gear, you need to do damage to the broccoli, so you’d think cooking would do the trick.

Unfortunately, studies have shown that common broccoli cooking methods, like boiling and microwaving, seriously reduce the amount of glucosinolates in the vegetable – even if you just zap it for a couple minutes. And myrosinase is super-sensitive to heat, too.

Hence, by far the largest amount of sulforaphane you can get from broccoli is by munching on raw florets. Ugh.

This got the team of researchers thinking about the results of stir-frying – the most popular method for preparing vegetables in China.

“Surprisingly, few methods have reported the sulforaphane concentrations in stir-fried broccoli, and to the best of our knowledge, no report has focused on sulforaphane stability in the stir-frying process,” the researchers noted in their study.

The team bought a bunch of broccoli from the local market and set to work, measuring the levels of compounds in the vegetables as they went.

First, they basically pulverized the broccoli, chopping it into 2 millimeter pieces to get as much myrosinase activity going as possible (remember, it happens when broccoli is damaged).

Then they divided their samples into three groups – one was left raw, one was stir-fried for four minutes straight after chopping, and the third was chopped and then left alone for 90 minutes before being stir-fried for four minutes as well.

The 90 minute waiting period was to see whether the broccoli would have more time to develop the beneficial compounds before being lightly cooked.

And that’s exactly what the team found – the broccoli that was stir-fried right away had 2.8 times less sulforaphane than the one left to ‘develop’ for longer.

“Our results suggest that after cutting broccoli florets into small pieces, they should be left for about 90 minutes before cooking,” the team concluded, adding that they didn’t test it but thought “30 minutes would also be helpful.”

We’re not sure we’re willing to commit to all that effort, though. The team does say they’re looking into ways to reduce the chopping needed, so watch this space – or just eat some raw broccoli.

The study was published in the Journal of Agricultural and Food Chemistry.

Eating Leafy Greens Daily May Help Keep Minds Sharp

To age well, we must eat well — there’s been a lot of evidence that heart-healthy diets help protect the brain.

The latest good news: A study recently published in Neurology finds that healthy seniors who had daily helpings of leafy green vegetables — such as spinach, kale and collard greens — had a slower rate of cognitive decline, compared to those who tended to eat little or no greens.

“The association is quite strong,” says study author Martha Clare Morris, a professor of nutrition science at Rush Medical College in Chicago. She also directs the Rush Institute for Healthy Aging.

The research included 960 participants of the Memory and Aging Project. Their average age is 81, and none of them have dementia. Each year the participants undergo a battery of tests to assess their memory. Scientists also keep track their eating habits and lifestyle habits.

To analyze the relationship between leafy greens and age-related cognitive changes, the researchers assigned each participant to one of five groups, according to the amount of greens eaten. Those who tended to eat the most greens comprised the top quintile, consuming, on average, about 1.3 servings per day. Those in the bottom quintile said they consume little or no greens.

THE SALT

As Bagged Salad Kits Boom, Americans Eat More Greens

After about five years of follow-up/observation, “the rate of decline for [those] in the top quintile was about half the decline rate of those in the lowest quintile,” Morris says.

So, what’s the most convenient way to get these greens into your diet?

“My goal every day is to have a big salad,” says Candace Bishop, one of the study participants. “I get those bags of dark, leafy salad mixes.”

A serving size is defined as a half-cup of cooked greens, or a cup of raw greens.

Does Bishop still feel sharp? “I’m still pretty damn bright,” she tells me with a giggle. She isn’t convinced that her daily salad explains her healthy aging.

“I think a lot of it is in the genes,” Bishop says, adding, “I think I’m lucky, frankly.”

She has other healthy habits, too. Bishop attends group exercise classes in her retirement community and she’s active on several committees in the community.

Many factors play into healthy aging — this study does not prove that eating greens will fend off memory decline. With this kind of research, Morris explains, scientists can only establish an association — not necessarily causation — between a healthy diet and a mind that stays sharp.

Still, she says, even after adjusting for other factors that might play a role, such as lifestyle, education and overall health, “we saw this association [between greens and a slower rate of cognitive decline] over and above accounting for all those factors.”

Some prior research has pointed to a similar benefit. A study of women published in 2006 also found that high consumption of vegetables was associated with less cognitive decline among older women. The association was strongest with greater consumption of leafy vegetables and cruciferous vegetables — such as broccoli and cauliflower.

And, as NPR has reported, there’s evidence that a Mediterranean-style diet — which emphasizes a pattern of eating that is rich in fish, nuts, vegetables and whole grains — may help stave off chronic diseases.

What might explain a benefit from greens?

Turns out, these vegetables contain a range of nutrients and bioactive compounds including vitamin E and K, lutein, beta carotene and folate.

“They have different roles and different biological mechanisms to protect the brain,” says Morris. More research is needed, she says, to fully understand their influence, but scientists do know that consuming too little of these nutrients can be problematic.

For instance, “if you have insufficient levels of folate in your diet you can have higher levels of homocysteine,” Morris says. This can set the stage for inflammation and a build-up of plaque, or fatty deposits, inside your arteries, which increases the risk of stroke. Research shows elevated homocysteine is associated with cognitive impairmentamong older adults.

Another example: Getting plenty of Vitamin E from foods in your diet can help protect cells from damage, and also has been associated with better cognitive performance.

“So, when you eat leafy greens, you’re eating a lot of different nutrients, and together they can have a powerful impact,” Morris says.

Kale, other Leafy Vegetables may Make your Brain Seem 11 Years Younger

Look into your salad bowl and think: If a fountain of cognitive youth were flowing in there, would you return every day?

In research that gives new meaning to the expression “salad days,” a study published recently finds that older people who ate at least one serving of leafy greens a day had a slower rate of decline on tests of memory and thinking skills than did people who rarely or never ate these vegetables.

The study was published in the journal Neurology.

After almost five years, regular consumers of such veggies as kale, spinach, collard greens and lettuce enjoyed a mental edge that was the equivalent of 11 years in age.

To be sure, the top tier of leafy-vegetable consumers started with cognitive scores that were slightly higher than those in the bottom tier. That’s probably a testament to the power of lifelong eating patterns.

But over five years, the pattern of mental aging differed markedly in these two groups. Study participants who ate an average of roughly 1.3 servings of leafy greens a day experienced a decline in test performance that was about half as steep as that of participants whose daily consumption was near-zero.

Those stark differences were evident even after the researchers took account of a host of factors that are known to affect mental aging, including age, gender, education, exercise, participation in cognitive activities, smoking and consumption of seafood and alcohol.

Let’s say you and your neighbor are both 75 and similar in most every way: You both completed the same amount of school, take regular walks together, don’t smoke, and gather with friends over an occasional beer.

But while you enjoy a little more than a bowl of greens every day, your pal barely touches the stuff.

This long-running study would predict that at 75, your memory and thinking skills are a notch stronger than your neighbor’s. Over the next five years, hers will decline twice as fast as yours.

By the time you’re both 80, a battery of exercises that test several types of memory, as well as the speed and flexibility of your thinking, may show that your mental age is typical of a 75-year-old’s. Meanwhile, your neighbor’s performance on the same cognitive tests may look more like that of an 86-year-old.

“It’s almost unbelievable,” said Martha Morris, the senior author of the study who studies nutrition and brain health at Rush University Medical Center in Chicago. “Eating these leafy greens was independently associated with slower cognitive decline. That tells you this single food group contains so many nutrients it could be brain-protective.”

Morris and her colleagues identified a small cluster of specific nutrients that appear to offer anti-aging benefits. The leafy greens that participants were asked about are generally rich in vitamin E, folic acid, vitamin K1, lutein and beta-carotene. While inconsistent, research has suggested that some or all of these nutrients may play some role in protecting the brain against inflammation, the accumulation of toxic proteins such as beta-amyloid, and neuronal damage and death.

For lifelong avoiders of leafy greens, the study doesn’t show that a late-life conversion to kale salads and spinach shakes will keep dementia at bay. But Morris said she thinks about nutrition the same way she thinks about exercise.

“You do get immediate benefits from eating healthy foods and exercising,” she said. “And you get long-term benefits.”

Dr. Lon Schneider, a specialist in dementia at the University of Southern California’s Keck School of Medicine, says the new study offers important insights into which nutrients in the Mediterranean diet help support health in aging. But it also underscores the complexity of dementia and cognitive aging — and the absence of a “silver bullet” to counter them.

“Dementia is a complex illness, as so many chronic illnesses are,” Schneider said. “It’s clearly not caused by one thing, and surely its onset and severity are not caused by one thing. This shows the environment is really important. Diet matters.”