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Elementary school students learn food science

Sixth-grade students from Hamasaki Elementary School in Los Angeles were surprised to learn that they could actually see iron in their breakfast cereal through a simple experiment involving ground up cereal, water and magnets. These same students also found out that learning about science could be fun.

The students were taking part in a celebration of 4-H National Youth Science Day at UC Cooperative Extension in Los Angeles County Sept. 24. LA County advisors and program coordinators teamed up to give the students the opportunity to learn about nutrition, physical activity and the environment through fun, interactive science-based activities. The students learned about the body’s need for iron in the diet, what types of foods are rich in iron and how to identify these foods by reading the nutrition facts label.

For the experiment, the students were given plastic bags filled with ground up, iron-fortified breakfast cereal and water. They learned that the small bag represents their stomachs after consuming a big bowl of iron-fortified cereal. The kids were instructed to move a magnet slowly across the outside of the bag. Lo and behold, they observed tiny black particles trailing behind the magnet – they could actually see the iron in the cereal mixture. The students learned that once the cereal makes its way into the stomach, the iron is separated and dissolved by stomach acid and absorbed into the body.

Everyone was eager to take a turn with the magnet, including the teachers and chaperones.

Ellen Sandor and Cynthia Avila, youth Food Stamp Nutrition Education Program and and Expanded Food and Nutrition Education Program program coordinators, and Brenda Roche, the nutrition, family and consumer sciences advisor, worked with the students to uncover the seemingly invisible mineral that is commonly fortified in many breakfast cereals.

Variations of this experiment are described on a number of different websites, including:

Other information presented to the students at the event included:

  • Climate change by Keith Nathaniel, the 4-H Youth Development advisor
  • Environmental and watershed conservation by Sabrina Drill, natural resources advisor
  • Physical activity and the science of physiology by Carly Marino, coordinator of the Power Play Campaign

For more information about the event, contact Roche at bkroche@ucdavis.edu, (323) 260-3299.

Students find iron in their breakfast cereal.
Students find iron in their breakfast cereal.

Posted on Wednesday, September 29, 2010 at 7:13 AM
  • Author: Brenda Roche

Obesity is linked with low earnings

Minimum-wage employees are more likely to be obese than those who earn higher wages, according to a new study by UC Davis public health researchers. The study is the latest in a growing body of evidence that shows being poor is a risk factor for unhealthy weight.

"Estimating the Effects of Wages on Obesity" was published in May 2010 in the Journal of Occupational and Environmental Medicine. The authors, DaeHwan Kim and John Paul Leigh, identified several possible reasons why lower wages could support the tendency to be obese:

  • Poorer people tend to live in less-safe neighborhoods with reduced access to parks and other means of physical activity

  • Healthy, lower-calorie foods tend to be more expensive

  • Low-income families have less access to healthier foods and often have to travel greater distances than others to find healthier food options and lower cost


"The outcome leads us to believe that raising minimum wages could be part of the solution to the obesity epidemic," Leigh said.

In a news release, Leigh noted that a novel statistic technique used for the study gave the scientists a chance to evaluate an independent factor that is definitely not caused by obesity - minimum wages.

UC Davis Cooperative Extension nutrition specialist Sheri Zidenberg-Cherr said experts are aware of the higher incidence of obesity among the poor, and believe that the causal relationship may go both ways.

"We know there have been cases of discrimination against the obese seeking employment for various types of positions," Zidenberg-Cherr said. "It is also true that, for minimum-wage earners, it is easier and cheaper to buy foods that are high in fat and sugar. They may not have the access or the education to make healthy food choices."

Leigh noted that the scientists' sample for the study were 85 percent men and 90 percent Caucasian.

"Future research should address wage and obesity correlations among samples that include more African-Americans, Hispanics, Asians and women," Leigh said. "Obesity is a complex problem that likely has multiple causes. The more we can pinpoint those causes for specific populations, the greater chances there are for reducing its impact."

Low wage earners are more likely to be obese.
Low wage earners are more likely to be obese.

Posted on Monday, September 27, 2010 at 7:27 AM

A new approach in teaching healthy eating

UC Cooperative Extension nutrition educators have discovered that, when it comes to teaching consumers how to eat right, a picture is worth of thousand words.

“We’ve been teaching people for years about MyPyramid and the dietary guidelines, serving sizes and the number of servings they should eat, but many were having a hard time translating that to what exactly to put on their plates,” said Cathi Lamp, the nutrition, family and consumer sciences advisor for Tulare County UCCE.

In an effort to simplify nutrition education, UCCE started with a graphic of a plate, with half designated for fruits and vegetables and a quarter each for protein and grains. However, the concept was still too abstract for concrete thinkers.

“Then we hit upon the idea of photographing familiar foods in the right proportions and showing actual serving sizes arranged on a plate,” Lamp said.

Lamp, and the nutrition, family and consumer sciences advisors for Fresno County, Connie Schneider, and Kern County, Margaret Johns, set out to review 24-hour recall surveys that had been conducted by participants in UCCE nutrition education classes. The 24-hour recall surveys, a mainstay in nutrition research, ask participants to write down everything they have eaten in the previous 24 hours. Each of the advisors focused on recalls from target population groups – Latinos, African-Americans and the general population.

Once they knew what foods people eat, Lamp, Schneider and Johns began the labor-intensive process of preparing and photographing test pictures showing healthy food combinations. Meals included chicken, pizza, spaghetti, sandwiches, tacos, pork chops, fish, stir fry, hamburger, soup and eggs.

Eighteen plates of food were photographed for initial, informal testing. Lamp took the photos to an education session at the local WIC office, where pregnant women and new mothers receive federal nutrition support.

“We handed out a little form and asked the moms if they could identify the foods, whether these were foods they would eat and, if not, what changes they would make,” Lamp said. “The WIC educators loved the images. They could see the value of images of healthy food right off the bat.”

The next step will be cognitive testing of the photos with target clientele, adjustment of the photos based on the results of the testing, retesting the photos in a nutrition education setting and analyzing the results.

Posted on Friday, September 24, 2010 at 6:26 AM

Imagine there’s no hunger ... It’s easy if you try

At 925 million, the number of hungry people in the world is unacceptably high.

To combat world hunger, many scientists are working on developing crops that can resist disease and withstand the elements, from drought to floods. One such scientist is Sean Cutler at UC Riverside, whose breakthrough discovery last year of pyrabactin has brought drought-tolerant crops closer to becoming reality and spawned new research in several labs around the world.

Pyrabactin is a synthetic chemical that mimics abscisic acid (ABA), a naturally produced stress hormone in plants that helps them cope with drought conditions by inhibiting growth. ABA has already been commercialized for agricultural use. But it has at least two disadvantages: it is light-sensitive and it is costly to make.

Enter pyrabactin. This chemical is relatively inexpensive, easy to make, and not sensitive to light. But is it free from drawbacks? Unfortunately, no. Unlike ABA, pyrabactin does not turn on all the “receptors” in the plant that need to be activated for drought-tolerance to fully take hold.

What does that mean? A brief lesson on receptors may be in order.

A receptor is a protein molecule in a cell to which mobile signaling molecules – such as ABA or pyrabactin, each of which turns on stress-signaling pathways in plants – may attach. Usually at the top of a signaling pathway, the receptor functions like a boss relaying orders to the team below that then proceeds to execute particular decisions in the cell.



It turns out that each receptor is equipped with a pocket, akin to a padlock, in which a chemical, like pyrabactin, can dock into, operating like a key. Even though the receptor pockets appear to be fairly similar in structure, subtle differences distinguish a pocket from its peers. The result is that while ABA, a product of evolution, can fit neatly in any of these pockets, pyrabactin is less successful. Still, pyrabactin, by being partially effective (it works better on seeds than on plant parts), serves as a leading molecule for devising new chemicals for controlling stress tolerance in plants.

Each receptor is equipped also with a lid that operates like a gate. For the receptor to be activated, the lid must remain closed. Pyrabactin is effective at closing the gate on some receptors, turning them on, but cannot close the gate on others.

Cutler and colleagues have now cracked the molecular basis of this behavior. In a receptor where the gate closes, they have found that pyrabactin fits in snugly to allow the gate to close. In a receptor not activated by pyrabactin, however, the chemical binds in a way that prevents the gate from closing and activating the receptor.

“These insights suggest new strategies for modifying pyrabactin and related compounds so that they fit properly into the pockets of other receptors,” Cutler says. “If a derivative of pyrabactin could be found that is capable of turning on all the receptors for drought tolerance, the implications for agriculture are enormous.”

So he and his colleagues continue their research on pyrabactin derivatives, having set their eyes on the prize: An ABA-mimicking, inexpensive and light-insensitive chemical that can be sprayed easily on corn, soy bean and other crops to help them survive drought – one effective approach to combating and preventing hunger worldwide.
Imagine that!

Posted on Wednesday, September 22, 2010 at 6:44 AM

What makes food grow - and why that matters

There’s a lot of attention paid to where food comes from nowadays. Less attention has been paid to what helps that food grow, but that’s an important part of the equation. Whether organic or conventionally grown, the tomatoes, lettuce, plums and other food we eat rely on nutrients in order to grow. One of the most important nutrients for plant productivity is nitrogen.

Nitrogen, which is ubiquitous in our atmosphere in a relatively inert, gaseous form, is not available to most plants unless it is transformed into a reactive form and added to soil, where plants can use it to grow. Most often nitrogen is applied to fields in the form of synthetic fertilizer, although organic production relies on other nitrogen sources, such as cover crops, manure, fish meal and poultry waste.

Agricultural production depends on nitrogen in order to grow reliable, high yielding crops. But this nitrogen, when it is applied to fields in the reactive form that plants can use, also tends to leak out into air and water and cause pollution when all the nitrogen applied to the field is not used up by the plants.

The California Nitrogen Assessment, a project of the Agricultural Sustainability Institute at UC Davis, is taking a hard look at the whole system of nitrogen use in California. While nitrogen is hugely important to producing the food and fiber that we all need, there may be ways to use it more efficiently and reduce the pollution problems it can cause. These problems include air and water pollution, which can have negative consequences for human and environmental health in California.

Since nitrogen is so important to producing the food that all of us eat, the Agricultural Sustainability Institute’s team has involved stakeholders from all around the agricultural system. The assessment team has sought insight from farmers and economists, policy makers and public health groups, and Californians whose drinking water has been polluted by nitrogen, forcing them to buy bottled water on a regular basis. There are many diverse perspectives and ideas about how nitrogen should be managed in California’s future. The assessment will provide a synthesis of the most up-to-date scientific knowledge on science, policy and practice to inform decision making on how to improve nitrogen management.

Thinking about where food comes from is one important part of understanding the food system. Learning about the trade-offs involved in other key agricultural inputs is another.

Find out more about nitrogen and the California Nitrogen Assessment at its website. If you are interested in becoming involved in the assessment as a stakeholder participant, visit the website for more information to learn how you can get involved.

Posted on Monday, September 20, 2010 at 6:33 AM
  • Author: Stephanie Ogburn

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