Health benefits of broccoli require the whole food, not supplements

October 11, 2011
New studies have found that the health benefits of broccoli depend on consumption of the whole food, rather than supplements. (Photo courtesy U.S. Department of Agriculture)

New research has found that if you want some of the many health benefits associated with eating broccoli or other cruciferous vegetables, you need to eat the real thing – a key phytochemical in these vegetables is poorly absorbed and of far less value if taken as a supplement.

The study, published by scientists in the Linus Pauling Institute at Oregon State University, is one of the first of its type to determine whether some of the healthy compounds found in cruciferous can be just as easily obtained through supplements.

The answer is no.

And not only do you need to eat the whole foods, you have to go easy on cooking them.

"The issue of whether important nutrients can be obtained through whole foods or with supplements is never simple," said Emily Ho, an OSU associate professor in the OSU School of Biological and Population Health Sciences, and principal investigator with the Linus Pauling Institute.

"Some vitamins and nutrients, like the folic acid often recommended for pregnant women, are actually better-absorbed as a supplement than through food," Ho said. "Adequate levels of nutrients like vitamin D are often difficult to obtain in most diets. But the particular compounds that we believe give and related vegetables their health value need to come from the complete food."

The reason, researchers concluded, is that a necessary enzyme called myrosinase is missing from most of the supplement forms of glucosinolates, a valuable phytochemical in cruciferous vegetables. Without this enzyme found in the whole food, the study found that the body actually absorbs five times less of one important compound and eight times less of another.

Intensive cooking does pretty much the same thing, Ho said. If broccoli is cooked until it's soft and mushy, its health value plummets. However, it can still be lightly cooked for two or three minutes, or steamed until it's still a little crunchy, and retain adequate levels of the necessary enzyme.

The new study was published in the Journal of Agricultural and Food Chemistry. It was supported by the National Institutes of Health.

Broccoli has been of particular interest to scientists because it contains the highest levels of certain glucosinolates, a class of phytochemicals that many believe may reduce the risk of prostate, breast, lung and colorectal cancer. When eaten as a raw or lightly-cooked food, enzymes in the broccoli help to break down the glucosinolates into two valuable compounds of intensive research interest – sulforaphane and erucin.

Studies have indicated that sulforaphane, in particular, may help to detoxify carcinogens, and also activate tumor suppressor genes so they can perform their proper function.

Most supplements designed to provide these glucosinolates have the enzyme inactivated, so the sulforaphane is not released as efficiently. There are a few supplements available with active myrosinase, and whose function more closely resembles that of the whole food, but they are still being tested and not widely available, Ho said.

Small amounts of the myrosinase enzyme needed to break down glucosinolates are found in the human gut, but the new research showed they accomplish that task far less effectively than does whole consumption.

Although broccoli has the highest levels of glucosinolates, they are also found in cauliflower, cabbage, kale and other cruciferous vegetables. The same cooking recommendations would apply to those foods to best retain their , Ho said.

Many people take a variety of vitamins, minerals and phytochemicals as supplements, and many of them are efficacious in that form, researchers say. Higher and optimal levels of popular supplements such as vitamins C, E, and fish oil, for instance, can be difficult to obtain through diet alone. Some researchers believe that millions of people around the world have deficient levels of vitamin D, because they don't get enough in their diet or through sun exposure.

But for now, if people want the real health benefits of broccoli, there's a simple guideline.

Eat your vegetables.

Explore further: Study confirms safety, cancer-targeting ability of nutrient in broccoli, other vegetables

Related Stories

Study confirms safety, cancer-targeting ability of nutrient in broccoli, other vegetables

June 9, 2011
Sulforaphane, one of the primary phytochemicals in broccoli and other cruciferous vegetables that helps them prevent cancer, has been shown for the first time to selectively target and kill cancer cells while leaving normal ...

More evidence that spicing up broccoli boosts its cancer-fighting power

September 13, 2011
Teaming fresh broccoli with a spicy food that contains the enzyme myrosinase significantly enhances each food's individual cancer-fighting power and ensures that absorption takes place in the upper part of the digestive system ...

Recommended for you

When traveling on public transport, you may want to cover your ears

November 22, 2017
The noise levels commuters are exposed to while using public transport or while biking, could induce hearing loss if experienced repeatedly and over long periods of time, according to a study published in the open access ...

Different types of alcohol elicit different emotional responses

November 22, 2017
Different types of alcohol elicit different emotional responses, but spirits are most frequently associated with feelings of aggression, suggests research published in the online journal BMJ Open.

Air pollution linked to poorer quality sperm

November 22, 2017
Air pollution, particularly levels of fine particulate matter (PM2.5), is associated with poorer quality sperm, suggests research published online in Occupational & Environmental Medicine.

Sunrise and sunset guide daily activities of city-dwellers

November 21, 2017
Despite artificial lightning and social conventions, the dynamics of daylight still influence the daily activities of people living in modern, urban environments, according to new research published in PLOS Computational ...

Older men need more protein to maintain muscles

November 21, 2017
The amount of protein recommended by international guidelines is not sufficient to maintain muscle size and strength in older men, according to a new study.

Exercising and eating well are greater contributors to health than standing at work

November 21, 2017
By now you've probably heard the edict from the health community: Sitting is the new smoking. Perhaps you've converted to a standing desk, or maybe you have a reminder on your phone to get up once an hour and walk around ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.