Spinach Recipes: Unlocking Powerful Health Benefits

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The latest scientific research confirms that correctly cooking raw vegetables can actually increase their nutritional value. 

Dr. Dean Kopsell, head of the Carotenoid Project at the University of Tennessee, takes us on an inside look into the latest scientific research on the health benefits of vegetables and the role of cooking in releasing their vital healing compounds. 

1. You are currently heading the Carotenoid Research Project at the University of Tennessee.  Could you tell us about the project?

My research area is vegetable crop physiology, with emphasis on the enhancement of nutritionally beneficial phytochemicals in vegetable crops for preventative and therapeutic disease reductions. 

My projects focus on environmental and genetic modifications that increase phytochemical concentrations.  This translates to providing information to producers and consumers about which vegetable crops, and cultivars, have the highest nutritional values, and what are the cultural growing practices that can maximize their phytochemical concentrations.

My main research focus involves the analysis of nutritionally important carotenoid phytochemicals.  Carotenoids are found in plants and are responsible for the brilliant colors we see in nature.  My lab is attempting to identify the best ways to grow vegetables such as spinach, kale, tomatoes, peppers, basil, onions, sweet corn, and broccoli to maximize carotenoid compounds in their edible tissues.  We are also starting to work with cancer and obesity research specialists to verify the nutritional and therapeutic impacts of our research. 

Medical and nutritional researchers are beginning to see the value of bioactive compounds in fruits and vegetables.  They have approached our group here at UT to ask about collaborative projects.  It is a very exciting time to be involved in phytochemical enhancement of fruits and vegetables. 

2. Spinach has become a symbol of healthy eating.  What are the main health benefits of the vegetable?

Spinach is a very nutritious leafy vegetable.  One of the projects in our lab measured the nutritional value of spinach from commercial sources and USDA germplasm collections.  What we found was the elemental concentrations, such as Ca, Mg, and K, and carotenoid phytonutrients differed up to 2.5 fold among the different varieties and cultigens of spinach.  

Spinach is one of many vegetable crops which possess important phytonutrient compounds called carotenoids.  Most of us know carotenoids as the red, orange, and yellow leaf pigments responsible for the brilliant fall leaf colors.  Carotenoids act as light-protective compounds for photosynthesis.  They dissipate energy from incoming solar radiation and also serve antioxidant functions.  Not surprisingly, carotenoids serve similar light-protective and antioxidant functions in our bodies as well.  We cannot produce carotenoids ourselves, and must get them from the foods we eat.  Vegetables are one of the main sources of carotenoids in human diets. 

Spinach has high concentrations of several carotenoids, especially lutein and zeaxanthin.  These two important pigments are selectively deposited in the macula region of the retina in our eyes, collectively called macular pigment.  Macular pigment filters out harmful ultra-violet light (like “natural sun glasses”) and helps prevent eye diseases such as cataracts and age-related macular degeneration. 

Nutritional and vision scientists have already made the association between increased carotenoid consumption and increased macular pigment in our eyes.  When we age, our diets change, and often times older adults cannot tolerate fresh vegetables.  Reducing vegetable consumption lowers carotenoid intake and decreases eye macular pigment concentrations.  This opens the door for aging eye diseases. 

3. Does cooking spinach significantly reduce nutrient content?  Is there a way to cook spinach that would minimally impact its health benefits?

This is an interesting question.  It is easy to give you the standard scientific response, “It depends…”  When you ask how cooking affects the nutritional value of spinach, it really depends on what nutritional components you’re asking about. 

For water-soluble vitamins (such as a vitamin C), steaming would reduce the amounts, because most of the vitamins would be in the bottom of the steaming pot in the water.  For fat-soluble phytochemicals (such as the carotenoids), steaming will actually increase availability and uptake. 

Fat-soluble carotenoids are found deep within plant membranes, and steaming acts to weaken those membranes to increase compound release.  If there is one general rule of thumb to follow when trying to get the most of the vegetables you eat, light cooking is the best.  Lightly sauté, steam, or blanch your vegetables to maximize total nutritional availability.  Through light cooking, you release fat-soluble compounds, and minimize losses of water-soluble compounds.

4. How has your research affected your view on healthy cooking and food consumption?

I grew up eating fresh vegetables out of the garden.  I’ve also developed a love for cooking.  The work that I do in my research program gives me an advantage in knowing the best way to grow vegetables for maximum nutritional value.  The research papers I read also explain how postharvest preparation and cooking methods maximize the availability of important phytochemicals. 

I also have the advantage of meeting and talking with the scientists who do this research.  I’ve spoken with scientists who have researched lycopene absorption from different tomato cultivars and from different tomato preparations (juice, paste, whole fruits, etc.).  Another scientist I’ve met determined the optimum length of time to steam broccoli to maximize concentrations of anticancer compounds. 

The great thing about my job is the information I’m exposed to when I go to meetings and read scientific articles.  I know that much of the material is beyond most consumers, but it is truly amazing to hear about the research people are conducting on behalf of vegetable producers, consumers, and the food preparation industry.  People should be comforted to know that scientists in this country are making great progress to ensure we have a safe and nutritious food system.

5. Do you feel contemporary scientific research has the power to influence national culinary trends?

Yes I do.  Some people may be frustrated with the lack of information available, or the apparent disconnect between the work performed in labs like mine and what occurs in the average kitchen.  One of the main reasons for the slow transfer of knowledge from science to the general public is the high costs associated with this type of research.  The agricultural industries in this country are still based on yield as the main motivating factor for both producers and consumers.  There is some attention given to crop quality, but most of the research that goes into commodities like corn, soybean, and cotton center on increasing in productivity or yield. 

For horticultural crops like fruits and vegetables, consumers are becoming increasingly aware of the connections between their health and the food they eat.  Thus, there is a growing need for information on quality and nutritional factors.  However, this research is extremely expensive. 

Take for instance research to increase the lycopene concentration in tomatoes.  Researchers need to grow the crops under different environmental growing conditions to see which practices have the greatest influence on tomato plant growth and lycopene in the fruits.  Once the crops reach maturity and the fruits are harvested, they have to be measured for lycopene.  Phytochemical lab analysis is labor intensive and expensive.  Tomato fruits need to be processed in much the same way as the commercial industry.  The lycopene compounds need to be extracted from the fruits and then measured with sophisticated lab equipment.  In science, the name of the game is numbers. 

You can’t just do an experiment once and say you have the definitive answer.  Studies must be replicated several times before you have the confidence that your results are due to the experimental treatments you’ve applied and not due to some unforeseen environmental influence or simply by chance alone. 

The scientific process is very powerful and has the ability to change the way we view the world around us.  It also holds the power to change the way we grow, harvest, process, prepare, and view the fruits and vegetable we eat.  I can tell you for certain that there are hard working scientists working to generate this important information; however, there are far too few of us in the field. 

It may sound backwards to some, but it really all starts with the consumer.  It people start demanding more nutritious foods, and make their voice heard with their dollars, marketers will start requesting higher quality from farmers.  Farmers will then turn to extension and research scientists for information on production and processing practices.  This process is working, but the wheels of progress are still slow to turn. 

Suggested Recipes:

Vegetarian Recipes
Vegetable Recipes
Easy Spinach Manicotti (Lacto)
Goat Cheese and Spinach Turnovers
Borekas Stuffed with Cheese and Spinach