Nutritional impact of elevated calcium transport activity in carrots

Vegetable and Fruit Improvement Center, Texas A&M University, College Station, TX 77845, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 03/2008; 105(5):1431-5. DOI: 10.1073/pnas.0709005105
Source: PubMed


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 approximately 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 (45)Ca 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 (42)Ca-labeled carrots and i.v. (46)Ca 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.

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Available from: Steven A Abrams, Dec 25, 2014
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    • "In a previous study, fruit-specific expression of FvOXDC in transgenic tomato lines was found similar in growth and development with their wild-type counterpart irrespective to a significant increase in mineral contents of fruits (Chakraborty et al., 2013). Other studies also supported that increase in calcium content in transgenic plants did not affect the plant growth in tomato, potato and lettuce (Chung et al., 2010;Kim et al., 2006;Morris et al., 2008;Park et al., 2004Park et al., , 2009). Moreover, transgenic indica rice developed by endospermspecific expression of soya bean ferritin found to contain higher iron and zinc levels and showed normal phenotype, morphology and fertility (Vasconcelos et al., 2003). "
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    • "This approach is also being successfully demonstrated in other crops such as maize, orange, cauliflower, tomato, yellow potatoes and golden canola (White and Broadley 2009). Similarly, GM carrot expressing high levels of a deregulated transporter which accumulated about 2-fold more Ca in the edible tissues was also developed (Morris et al., 2008, Carvalho and Vasconcelos 2013). In contrast with the 'Golden Rice', the feeding trials using this labeled carrot proved that Ca absorption was considerably increased in both animal models with diets having the GM carrot but not all the increased Ca was bioavailable (Murray-Kolb et al., 2002). "
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    • "Filipino women by measuring serum-ferritin, total body iron and hemoglobin during a 9- month trial with modest results.[7] Furthermore, Morris et al. investigated whether the increase of calcium accumulation in carrots leads to an increase in calcium intake upon consumption in both humans and mice.[8] Recently, Castorena-Torres et al. reported on the folate bio-availability from lyophilized biofortified tomatoes using a murine model, making a comparison with orally dosed synthetic 5-methyltetrahydrofolate (5-MTHF) and folic acid (FA). "
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