The best health benefits of broccoli come from eating the whole plant rather than from supplemental vitamins say researchers who determined that a key phytochemical in broccoli-related vegetables is poorly absorbed when in a vitamin pill form.
Supplemental vitamins play an important part in our daily health. Although many foods are natural sources of vitamins, some cannot be easily consumed in recommended daily allowances. For many, the amount of plant or fish required at mealtimes to reach recommended levels on a daily basis is prohibitive because of cost, availability and time. Examples of vitamins available as supplements that allow us to meet recommended daily doses include vitamins C, D, E, and nutrients from fish oil.
However, not all vitamins in supplemental pill forms help us achieve their healthful benefits. Broccoli and other cruciferous vegetables are examples of plants that need more than just their vitamin content extracted and pressed into a pill in order to provide their full benefit. They also require specific enzymes for absorption.
Cruciferous plants are members of the cabbage family and include broccoli, cauliflower, Brussels sprouts, cabbage, kale and bok choy. They are valued for their high content of vitamins, phytochemicals, minerals and fiber and are believed to play a significant dietary role in not only in preventing cancer, but stopping existing cancer growth. For men, a diet high in cruciferous vegetables is linked to lower risk of prostate cancer.
According to a recent study published in the Journal of Agricultural and Food Chemistry by scientists in the Linus Pauling Institute at Oregon State University, researchers wanted to determine if the benefits of nutrients found in cruciferous vegetables can be received from pills rather than from having to derive the nutrients solely through eating veggies.
According to an OSU news release, "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 broccoli and related vegetables their health value need to come from the complete food."
What the researchers found was that a type of essential phytochemical called glucosinolates found in broccoli requires the presence of an enzyme called myrosinase for absorption in the human gut. Vitamin supplements of glucosinolates do not contain the enzyme and therefore the human gut absorbs between 5-8 times less of the beneficial glucosinolates packed into pill form in comparison to eating whole foods.
The researchers also found that how broccoli is cooked affects the absorption of its vitamins. Cooking broccoli at too high of a temperature for too long can inactivate the myrosinase enzyme and significantly decrease vitamin absorption. The authors recommend cooking broccoli lightly for 2 or 3 minutes or steaming broccoli or other cruciferous vegetables rather than pan frying or boiling.
OSU News and Research Communications: “Health benefits of broccoli require the whole food, not supplements”
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