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Written by Truth About Trade & Technology
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Monday, 24 November 2008 17:38 |
USDA / ARS
November 19, 2008
Carrots Genetically Engineered to Express Elevated Levels of Calcium - Research funded by the USDA Agricultural Research Service at the Baylor College of Medicine has shown that carrots can be genetically " ... modified to have higher amounts of calcium ... [and] that the research could be used to add this valuable nutrient to other crops ... In randomized trials [the BCM researchers] labeled these modified carrots with isotopic calcium and fed them to mice and humans to assess calcium bioavailability ... Both the mice and human feeding studies demonstrate increased calcium absorption from sCAX1-expressing carrots compared with controls. These results demonstrate an alternative means of fortifying vegetables with bioavailable calcium ..."
Document Title: The title of the November 19, 2008 USDA ARS News Release is "Increasing Calcium in Carrots and Other Vegetables"
The title of the PNAS research paper is "Nutritional impact of elevated calcium transport activity in carrots"
Author(s): Jay Morris*,†, Keli M. Hawthorne†, Tim Hotze†, Steven A. Abrams†, and Kendal D. Hirschi*,†,‡
Author Affiliations
*Vegetable and Fruit Improvement Center, Texas A&M University, College Station, TX 77845; and
†U.S. Department of Agriculture/Agriculture Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
Organization: USDA ARS Press Office
Summary: The text of the USDA ARS News Release follows
Carrots have been modified to have higher amounts of calcium, according to studies by Agricultural Research Service (ARS)-funded scientists who report that the research could be used to add this valuable nutrient to other crops.
The current U.S. recommended average intake of calcium for adults aged 19 to 50 is 1,000 milligrams daily. But inadequate dietary calcium is a global concern, and poor diets and exercise habits prevent many people from achieving and maintaining optimal bone health. Calcium is a key component for healthy bones.
At the Children’s Nutrition Research Center (CNRC) in Houston, Texas, CNRC professors of pediatrics Kendal Hirschi and Steven Abrams boosted calcium levels by inducing carrots to express increased levels of the gene sCAX1, which enables the transport of calcium across plant cell membranes.
To determine the bioavailability of the calcium in the modified carrots, 30 volunteers—15 females and 15 males of various ethnic backgrounds and in their early to late 20s—ate single meals containing regular or modified carrots, which were labelled with a stable isotope of calcium.
After two weeks, the researchers found that the calcium intake of volunteers who consumed the modified carrots increased by 41 percent, compared to those who ate regular carrots.
Read more about this research in the November/December 2008 issue of Agricultural Research magazine at
http://www.ars.usda.gov/is/AR/archive/nov08/carrots1108.htm
CNRC is operated by Baylor College of Medicine in cooperation with Texas Children's Hospital and ARS, a scientific research agency of the U.S. Department of Agriculture.
The abstract of the PNAS journal article follows
Nutrition recommendations worldwide emphasize ingestion of plant-based diets rather than diets that rely primarily on animal products. However, this plant-based diet could limit the intake of essential nutrients such as calcium. Osteoporosis is one of the world's most prevalent nutritional disorders, and inadequate dietary calcium is a known contributor to the pathophysiology of this condition. Previously, we have modified carrots to express increased levels of a plant calcium transporter (sCAX1), and these plants contain ≈2-fold-higher calcium content in the edible portions of the carrots. However, it was unproven whether this change would increase the total amount of bioavailable calcium. In randomized trials, we labeled these modified carrots with isotopic calcium and fed them to mice and humans to assess calcium bioavailability. In mice feeding regimes (n = 120), we measured 45Ca incorporation into bones and determined that mice required twice the serving size of control carrots to obtain the calcium found in sCAX1 carrots. We used a dual-stable isotope method with 42Ca-labeled carrots and i.v. 46Ca to determine the absorption of calcium from these carrots in humans. In a cross-over study of 15 male and 15 female adults, we found that when people were fed sCAX1 and control carrots, total calcium absorption per 100 g of carrots was 41% ± 2% higher in sCAX1 carrots. Both the mice and human feeding studies demonstrate increased calcium absorption from sCAX1-expressing carrots compared with controls. These results demonstrate an alternative means of fortifying vegetables with bioavailable calcium.
Source: November 19, 2008 USDA ARS Press Release and the study published in the February 5, 2008 issue of PNAS
Web site: The November 19,2008 USDA ARS News Release is posted at
http://www.ars.usda.gov/is/pr/2008/081119.htm
The February 5, 2008 PNAS research report, titled "Nutritional impact of elevated calcium transport activity in carrots" is posted at
Nutritional impact of elevated calcium transport activity in carrots
Contact: Reprint requests and questions may be directed to Kendal D. Hirschi, Ph.D., Professor of Pediatrics-Nutrition at the Baylor College of Medicine in Houston, Texas at 713 798 7011; fax: 713 798 7171; e-mail: KendalH@BCM.TCM.edu
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