2006 Annual Report
Year 1 (Addressed in FY2005) Complete 1st yr of wheat & buckwheat Se accumulation studies (1.1) Complete transgenic wheat accumulation of Se study (1.1) Develop cells lines and constructs for antioxidants & gene expression study (1.5) Develop Se speciation methodology (1.1) Complete interim blood analyses for Fe excretion study & write initial paper (1.9) Enroll subjects in elemental Fe powder study (2.1) Complete antibody prep & perform studies on up/down regulation of mineral transport in Caco-2 cells (3.1). Complete studies on Cu transporter trafficking in Caco-2 cells given high Zn media (3.2).
Year 2 (Addressed in FY2006) Complete 2nd yr of wheat & buckwheat Se accumulation studies (1.1) Complete anti-oxidants & gene expression study (1.5) Complete 1st yr of organic/conventional foods study (1.1) Report transgenic wheat study (1.1) Complete Se speciation in wheat study (1.1) Develop Zn algorithm & prepare paper (1.7) Enroll subjects in Zn requirement study (1.6) Complete elemental Fe powders study (2.1) Wrap up studies on up/down regulation of mineral transport in Caco-2 cells. Write manuscripts (3.1) Wrap up studies on Cu transporter trafficking. Write manuscripts (3.2)
Year 3 (Addressed in FY2007) Complete feeding portion of human high-Se beef study (1.3) Report antioxidants & gene expression study (1.5) Report wheat & buckwheat accumulation studies (1.1) Complete 2nd yr of organic/conventional foods study (1.1) Complete high-Se beef and aberrant crypt study (1.3) Complete Zn requirement study (1.6) Report elemental Fe powders study (2.1) Complete studies on low mineral intakes, metal transporters, and cadmium accumulation in intestinal cells (3.3) Complete studies on relationship between Cu deprivation & Hephaestin activity (3.4)
Year 4 (Addressed in FY2008) Complete analyses for human high-Se beef study (1.4) Complete differences in bioavailability of mineral nutrients from organic/conventional broccoli (1.2) Report high-Se beef and aberrant crypt study (1.3) Complete study of phytate X Ca & Zn bioavailability (1.8) Report Zn requirement study (1.6) Complete study on validation of Caco-2 cell results with human absorption results on iron bioavailability from agricultural products (2.2) Wrap up Cu/Heph/Fe absorption studies. Write manuscripts (3.4) Complete study on marginal mineral & Cd exposure, analyze data (3.5).
Year 5 (Addressed in FY2009) Report human high-Se beef study (1.4) Complete comparison of high-Se foods aberrant crypt study (1.2) Report comparison of high-Se foods and aberrant crypt study (1.3) Report organic & conventional foods study (1.1) Report study of phytate X Ca & Zn bioavailability (1.8) Complete final report of Fe excretion data (1.9) Report microencapsulated Fe study (2.2) Wrap up studies in objective 3.5. Write manuscripts. Complete new 5-year proposal.
c. Serum pro-hepcidin is not correlated with iron absorption in premenopausal women: Hepcidin, a recently discovered peptide with antimicrobial properties, is proposed to play a central role in the biological regulation of iron absorption. Iron absorption measured in 28 premenopausal women correlated inversely with serum ferritin, an indicator of body iron stores, but was unrelated to serum pro-hepcidin concentrations. This newly published research suggested limitations of a commonly used immunological assay of a hepcidin precursor, and emphasized the need to develop a more specific assay of serum hepcidin. A better understanding of the biological control of iron absorption will help in developing recommendations for iron intake, especially for people with chronic infection or inflammatory diseases. (Human Nutrition Program 107, Component 2: Bioavailability of Nutrients and Food Components.)
d. Ascorbic acid enhancement of iron absorption is not identical for all forms of iron: Ascorbic acid consumed in the same meal substantially enhances absorption of iron from food, but if an elemental iron powders used for food fortification is poorly absorbed, its absorption may also be less influenced by ascorbic acid. In research with 56 volunteers, ascorbic acid improved iron absorption from a breakfast cereal by four times if fortified with ferrous sulfate, but only doubled absorption when fortified with an electrolytic iron irradiated for the research. Although irradiation likely reduced absorption of the electrolytic iron, other iron powders that are poorly absorbed may also be less effectively enhanced by ascorbic acid, and this could be an important consideration when choosing iron fortificants to combat iron deficiency anemia. (Human Nutrition Program 107, Component 2: Bioavailability of Nutrients and Food Components.)
e. Providing excess iron to rats by diet or injections does not cure the anemia of copper deficiency. Copper deficiency produces iron deficiency and anemia in rats and pigs by inhibiting an iron transport facilitator, hephaestin, in the intestinal cells. Doses of iron by diet or injections at three times the requirement had no effect on the signs of anemia induced in copper deficient rats. This research suggested that anemia of copper deficiency occurs primarily because of low iron absorption and inefficient loading of iron into transferrin because of very low copper-dependent ceruloplasmin activity. This then leads to inefficient delivery of iron to the erythroid cells for heme and hemoglobin synthesis. (Human Nutrition Program 107, Component 2: Bioavailability of Nutrients and Food Components.)
f. Selenium bioavailability varies in different mill fractions of wheat: Portions of cooked milled wheat fractions, flour, shorts, and bran containing selenium, were fed to rats. Bioavailability of selenium from flour was near 100%, from shorts, 85% and from bran, it was only 60%. These results indicate that high selenium wheat products, mainly those made from refined flour alone might be particularly well suited for use as a dietary selenium supplement. (Human Nutrition Program 107, Component 2: Bioavailability of Nutrients and Food Components.)
g. Greater mineral concentrations in historical varieties of wheat: Mineral analysis of wheat varieties grown under similar conditions showed that historical varieties were significantly higher in copper, iron, magnesium, manganese, phosphorus, selenium, and zinc than modern varieties. Results showed that modern wheat varieties require increased consumption of whole wheat bread to achieve the same percentage of the recommended dietary allowance (RDA) levels attainable by historical varieties high in mineral content. Selenium and iron concentrations were not associated with yield, suggesting the possibility for uncomplicated improvement, while weak to moderate negative correlations between yield and the other six minerals suggest a possible biological trade-off, and genetic improvement for these minerals may be more difficult to achieve. (Human Nutrition Program 107, Component 2: Bioavailability of Nutrients and Food Components.)
- Demonstrated that the antioxidant activity of thioredoxin reductase is regulated by multiple dietary components, especially selenium and sulforaphane, and that silencing thioredoxin reductase results in greatly increased oxidative stress. An improved understanding of how diet influences oxidative stress will help determine dietary recommendations that can reduce the risk of chronic diseases such as cancer.
- Found that selenium accumulated by grains grown on high-selenium soils was highly bioavailable to humans and animals from processed wheat, but that selenium from buckwheat was less bioavailable to rodents than pure chemical sources of selenium. The selenium enhancement of grains is potentially useful for increasing dietary selenium intakes, with possible health benefits related to the risk of chronic diseases.
- Incorporated a selenium accumulation gene into wheat, and tested the effects of various growing conditions to increase the uptake of selenium by the transfected cultivars. (in collaboration with investigators at USDA/ARS, Albany, CA, and USDA/ARS, Houston, TX). Development of selenium accumulating strain of wheat may someday allow production of wheat with extremely high concentrations of selenium which could be used as a source of supplemental Se or as a selenium-fortificant in cereal grain-based products.
- Developed methods to determine the chemical form of the selenium in foods, especially selenium in methylated forms that may be especially anticarcinogenic. The selenium compounds in dried vegetable powder were extracted and analyzed by HPLC coupled to inductively coupled plasma mass spectrometry. Further development of this methodology will allow us to better predict the bio-activity of selenium from numerous common plant foods.
- Demonstrated the potential antioxidant properties of selenium-enriched broccoli, which in rat diets was associated with decreased risk of some cancers. Extracts of selenium-enriched broccoli or of broccoli rich in sulforaphane effectively reduced DNA strand breaks in cultured liver cells of rats. Because DNA strand breaks are a major initiating event of many cancers, these results suggest that some of the cancer protective effects of sulforaphane and selenium may be protection against oxidative stress.
- Discovered a novel role for selenium in the up-regulation of cell cycle related genes that may lead to a better understanding of the essentiality of selenium as a nutrient and its involvement in cancer prevention.
- Demonstrated that, compared to a conventional farming technique, an organic farming method had limited influence on several nutritional characteristics of broccoli, including trace minerals, multiple individual glucosinolates, primary glucosinolate breakdown products, vitamin C and phenolic acids.
- Discovered that enhancing the selenium content of broccoli decreased total glucosinolate content, specifically sulforaphane, and changed the phenolic profile, especially reducing the content of hydroxy-cinnamic acids, suggesting that it may not be possible to simultaneously maximize all bioactive ingredients in a food, as enrichment with one compound may cause a concomitant decrease in another.
- Determined that zinc interference with copper transport appears unrelated to the expression of the human copper transporter, ATP7b. An understanding of the interaction between copper and zinc absorption will be useful in setting recommendations for balanced dietary intakes of the two elements.
- Confirmed that copper deficiency reduces iron absorption in rats of both sexes, resolving some mixed results from other laboratories. An understanding of the role of copper in iron absorption will be useful in setting recommendations for balanced dietary intakes and addressing the causes of nutritional anemias.
- Demonstrated that impaired iron absorption in copper deficient animals is associated with a reduction in the copper-containing hephaestin protein. Further understanding of the role of copper in iron absorption will be useful in resolving the problems of nutritional anemias that are not responsive to supplemental iron.
- Showed that in addition to impairing iron absorption, copper deficiency impairs red blood cell formation. An enhanced understanding of the role of copper in blood cell formation and hemoglobin synthesis will help set recommendations for dietary copper intakes.
- Discovered that marginal intakes of zinc, iron, and calcium greatly enhanced the accumulation of cadmium in the upper small intestine, independent of intestinal metallothionein concentrations, leading to a higher accumulation of the toxic metal in the liver and kidneys. This suggests that populations with these nutrient deficiencies are especially susceptible to cadmium toxicity.
- Demonstrated that the 10% of people of Northern European origin who inherited the hemochromatosis mutation from one parent (heterozygous carriers) absorbed both heme and nonheme iron similar to those without the mutation, even from a meal highly fortified with iron and vitamin C, suggesting that current food iron fortification policies do not place this large group at increased health risk.
- Demonstrated that elemental iron powders commonly used to fortify staple foods with iron were less bioavailable to rats than iron from ferrous sulfate, and commercial versions differed considerably, suggesting that higher concentrations of these forms may be needed if they are used in international iron fortification programs.
- Showed that reduced and electrolytic iron sources were approximately 50 and 85% as effective as ferrous sulfate and 5 mg iron in the heme form was half as effective as 50 mg of iron from ferrous sulfate for improving body iron in premenopausal women. This research with humans will help to determine the most useful forms of iron to use in supplementation and fortification programs to reduced iron deficiency anemia worldwide.
The following accomplishment aligns with Human Nutrition Program 107, Component 4: Nutrient Requirements:
- In a sensitive assessment of iron excretion in women as well as men, found that iron excretion is unrelated to body iron status in men, but that it determines the iron status of pre-menopausal women, because of the substantial influence of menstrual iron losses. Such iron excretion data from women will contribute to setting dietary recommendations for women’s iron intake, with less need to extrapolate from measurements in men.
JR Hunt participated in the National Academies, Institute of Medicine, Food and Nutrition Board workshop on DRI Research Recommendations, Washington DC, June 7-8, 2006, giving an invited presentation, “Fresh Perspectives: Research recommendations on DRIs for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc”.
JR Hunt provided written consultation on a project concerning iron supplementation for the Pan-American Health Organization.
Hunt, J.R. 2005. Dietary and physiological factors that affect absorption and bioavailability of iron. International Journal for Vitamin and Nutrition Research. 75(6):375-384.
Hadley, K.B., Johnson, L.K., Hunt, J.R. 2006. Iron absorption by healthy women was not associated with either serum or urinary pro-hepcidin. American Journal of Clinical Nutrition. 84:150-5.
Swain, J.H., Johnson, L.K., Hunt, J.R. 2006. An irradiated electrolytic iron fortificant is poorly absorbed by human subjects and is less responsive than FeSO4 to the enhancing effect of ascorbic acid. Journal of Nutrition. 136:2167-2174.
Hunt JR. Bioavailability of iron, zinc and copper as influenced by host and dietary factors. In: Food and Nutrition Board, Institute of Medicine, National Academy of Sciences report on “Food and Nutrition Board: Institute of Medicine. Mineral Requirements for Military Personnel; Levels Needed for Cognitive and Physical Performance During Garrison Training. Washington, D.C.: National Academy Press, 2006, pp. 265-277.
Finley, J.W. 2006. Bioavailability of selenium from foods. Nutrition Reviews. 64(3):146-151.
Finley, J.W. 2005. Bioactive compounds and designer plant foods: the need for clear guidelines to evaluate potential benefits to human health. Chronica Horticulturae. 45(3):6-11.
Reeves, P.G., Johnson, W.T. 2006. Copper. In: Driskell, J.A., Wolinsky, I., editors. Sports Nutrition: Vitamins and Trace Elements, 2nd Edition. Boca Raton, FL:CRC Taylor & Francis Group. p. 235-252.
Keck, A., Finley, J.W. 2006. Aqueous extracts of selenium-fertilized broccoli increase selenoprotein activity and inhibit DNA single-strand breaks, but decrease the activity of quinone reductase in Hepa 1c1c7 cells. Food and Chemical Toxicology. 44:695-703.
Keck, A.S., Finley, J.W. 2006. Database values for selenium do not reflect selenium contents of grain, cereals and other foods grown or purchased in the upper midwest of the United States. Nutrition Research. 26:17-22.
Swain, J.H., Penland, J.G., Johnson, L.K., Hunt, J.R. 2006. Energy, mood and attention did not consistently improve with iron status in non-anemic women with moderate to low iron stores [abstract]. FASEB J. 20(4):A191.
Hunt, J.R., Johnson, L.K. 2006. Iron excretion of healthy men and women, measured by isotope dilution [abstract]. FASEB J. 20(4):A194.
Beisiegel, J.M., Glahn, R.P., Welch, R.M., Menkir, A., Maziya-Dixon, B.B., Hunt, J.R. 2006. A caco-2 cell model predicts relative iron absorption from tropical maize by women [abstract]. FASEB J. 20(4):A624.
Beisiegel, J.M., Klevay, L.M., Hunt, J.R. 2006. Healthy postmenopausal women adapt to reduce zinc absorption in response to zinc supplementation [abstract]. FASEB J. 20(5):A985.
Hadley, K.B., Hunt, J.R. 2006. Zinc regulation of skeletal matrix remodeling activities in growing rats [abstract]. FASEB J. 20(4):A626.
Hunt, J.R. 2006. Absorption of nonheme, but not heme iron, is substantially reduced with high iron stores [abstract]. Journal of the American Dietetic Association. 106(8)S2:A-42.
Finley, J.W. 2005. Selenium and sulforaphane from broccoli interact to alter gene expression and protection against oxidative stress in cultured cells [abstract]. Presented at the 230th ACS National Meeting, Washington DC, Aug 28 - Sep 1, 2005.
Reeves, P.G., DeMars, L.C. 2006. Anemia in Cu-deficient rats was not reversed by administering high amounts of Cu-free Fe, either parenterally or by diet [abstract]. Journal of Federation of American Societies for Experimental Biology. 20(4):A193.
Reeves, P.G., Saari, J.T. 2005. Bioavailability of copper from cooked dry beans [abstract]. Annals of Nutrition and Metabolism. 49(Suppl 1). p.2.3.
Reeves, P.G., Finley, J.W. 2006. One-half cup of dry cooked pinto beans per day in addition to the regular diet lowered serum lipids in humans [abstract]. Presented by John W. Finley at Experimental Biology 2006, San Francisco, CA, March 31 - April 5, 2006.
Reeves, P.G., Demars, L.C. 2006. Signs of iron deficiency in copper-deficient rats are not affected by iron supplements administered by diet or by injection. Journal of Nutritional Biochemistry. 17:635-642.
Reeves, P.G., Leary, P.D., Gregoire, B.R., Finley, J.W., Lindlauf, J.E., Johnson, L.K. 2005. Selenium bioavailability from buckwheat bran in rats fed a modified AIN-93g Torula yeast-based diet. Journal of Nutrition. 135:2627-2633.