Progress 10/01/08 to 09/30/11
Outputs
OUTPUTS: As a result of our presentations and publications on iron content and bioavailability in clams, the USDA National Nutrient Database for Standard Reference (Release #24) has updated their data on clam iron content to reflect our findings. The Co-I has been invited to present our research at the 2012 EPS Global International Forum of Analytical Sciences meeting, Bangkok, Thailand, January 17-18, 2012 and has been contacted by Better Homes and Gardens to fact check an 2011 article that discusses clams as food source of iron. A "Got Nutrients" website was developed and daily nutrition messages are emailed to over 650 subscribers Over this last year, 25 nutrition messages related to iron deficiency, iron containing foods and factors that would affect the bioavailability of iron absorption were sent out. Subscribers are a combination of nutrition professionals (dietitians, cooperative extension personnel, and nutrition educators). These subscribers come from at least 44 Universities from around the country and world; 26 members are from governmental agencies, and 28 are from health agencies. Conference presentations that disseminated results to nutrition professionals: 1) Lai, J.,Dobbs, J., and Dunn, M.A. (2009) Clam Products as Food Sources of Iron: Iron Content and Bioavailability Relative to Beef. 19th International Congress of Nutrition, October 4-9, 2009, Bangkok, Thailand. 2) Lai, J., Dobbs, J., Dunn, M.A. and Titchenal, A. (2008) Clams illustrate food iron sources tower of babel. 32th National Nutrition Databank Conference, May 12-14, Ottawa, Canada. 3) Dobbs, J., Dunn, M.A., Lai, J. and Titchenal, A. (2008) Can Caco-2 cell technology be adapted to develop a relative iron bioavailability database 32th National Nutrition Databank Conference, May 12-14, Ottawa, Canada. 4) Lai, J., Dobbs, J. and Dunn, M.A. (2011) Iron content and iron bio-availability in plant-based foods commonly recommended for the prevention or treatment of iron deficiency. 7th Asia Pacific Conference on Clinical Nutrition. June 5-9, 2011, Bangkok, Thailand. Available at: http://www2.kenes.com/apccn/scientific/Pages/ListofAbstracts.aspx PARTICIPANTS: Individuals: Michael A. Dunn, PD - Supervised all aspects of the project; directed all personnel involved in collecting experimental data; supervised the writing of all publications; and collaborated with all co-PDs in their respective roles. Joannie Dobbs, Co-PD - Identified and reviewed healthcare websites that promote dietary iron sources; ranked food sources of iron as promoted on websites; assisted PD in purchasing and preparing top-10 ranked foods for analysis; disseminated our findings to consumers and stakeholders. Halina Zaleski, Co-PD - Assisted the PD with statistical analysis of experimental data. Yong Soo Kim, Co-PD - assisted the PD with caco-2 cell culture methods development and training graduate students in cell culture techniques. Jennifer Lai, MS graduate research assistant - conducted the food preparation and laboratory assays to measure iron content and bioavailability of the food products tested; trained a new graduate student to assist with the project, wrote her MS thesis on this project, assisted in the writing of two journal publications, and three abstracts. Tony Perfecto, MS graduate research assistant - Assisted Jennifer Lai with food preparation and laboratory assays. Training or professional development: The project formed the basis for the MS thesis of Jennifer Lai (graduated December, 2009), and has trained another MS student,Tony Perfecto, in the methods he will use in his MS thesis research. TARGET AUDIENCES: Target audiences include the general public, healthcare websites and their visitors, practicing health professionals, and nutrition textbook authors/editors. Groups that would most benefit from valid information on iron sources include: children, women of reproductive age, vegetarians, individuals that donate blood and the elderly. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We learned that "clams" were identified as the food most often recommended on healthcare websites as the best source of iron to prevent iron deficiency. Other foods commonly listed within the top-ten sources of iron were soybeans, chickpeas, lima beans, kidney beans, tofu, and spinach. Our research indicates that these food recommendations are not accurate and should be modified. Change in knowledge about clams: Firstly, clams were found to contain very little heme iron and should not be recommended as a replacement for other sources of heme iron in the diet such as lean red meat and dark poultry. Secondly, several clam products were shown to have low total iron content and/or low iron bioavailability and, therefore, should not be recommended as good sources of iron. Canned and pouched minced clams in particular were low in iron content (less than 1 mg/100g compared to 3.5 mg/100g for lean beef). Live clams contained higher amounts of iron (2.5 to 5.6 mg/100g), but the amount of bioavailable iron was very low indicating that the iron in live clams may be insoluble iron trapped as grit in the clam's digestive tract. Therefore, live clams should not be recommended as a good source of iron. Only whole baby clams contained the high levels of iron reported on websites (17 to 53 mg/100g), however, the amount of bioavailable iron in these clams was variable and some samples provided only as much bioavailable iron as the low-iron minced clams. Again, this may be related to the iron in whole baby clams being insoluble iron contained in the grit within the clam. Furthermore, most whole baby clam samples contained high levels of aluminum and, therefore, consumers may ingest more than the tolerable upper limit of aluminum. Thirdly,the bioavailability of the iron in clams was strongly inhibited by co-consumption of black tea. This indicates that polyphenols in tea, coffee, wine, and many fruits and vegetables can inhibit iron absorption from clams. Change in knowledge about legumes, tofu and spinach as sources of iron: We learned that these plant products are not good sources of iron. All of the following products purchased at local supermarkets were found to contain less that 1.8 mg iron per serving: edamame, chickpeas, lima beans, kidney beans, soft tofu, firm tofu, and spinach. Only soybeans and lentils contained 1.8 mg iron/serving, enough iron to be called a "good" iron source by the FDA's definition. However, the amount of bioavailable iron in all of these products was low. One serving provided less than one third the amount of bioavailable iron in a serving of beef or 9.8 mg of ferrous sulfate. Co-consumption of vitamin C is often recommended as a means to increase iron bioavailability from plant products, but we found that vitamin C had no effect on bioavailability from tofu, and only a small enhancing effect in soybeans. Overall our research indicates that information on good sources of iron needs to be revised and iron bioavailbility needs to be considered when recommending a food as a good source of iron. Possibly the most critical need is to identify new plant sources of iron that have high iron content and good iron bioavailability.
Publications
- Lai, J.F., Dobbs, J. and Dunn, M.A. (2011) Evaluation of clams as a food-source of iron: total iron, heme iron, aluminum, and in-vitro iron bioavailability in live and processed clams. Journal of Food Composition and Analysis (in press).
- Lai, J., Dobbs, J. and Dunn, M.A. (2011) Iron content and iron bio-availability in plant-based foods commonly recommended for the prevention or treatment of iron deficiency. 7th Asia Pacific Conference on Clinical Nutrition. June 5-9, 2011, Bangkok, Thailand. Available at: http://www2.kenes.com/apccn/scientific/Pages/ListofAbstracts.aspx
- Lai, J.F., Dobbs, J., Dunn, M.A., Tauyan, S. and Titchenal, C.A. (2009) Inconsistent values for iron content complicate recommending clams as an iron source. J Food Comp and Analysis: S78-S82.
- Lai, J., Dobbs, J., and Dunn, M.A. (2009) Clam Products as Food Sources of Iron: Iron Content and Bioavailability Relative to Beef. Annals of Nutrition and Metabolism 55: Supplement 1 (abstract), 19th International Congress of Nutrition, October 4-9, 2009, Bangkok, Thailand
- Lai, J. (2009) Are clams a good source of iron Evaluation of total iron content and iron bioavailability in processed clam products using the in-vitro digestion caco-2 cell method. M.S. Thesis. Univ. Hawaii, Manoa. 144p.
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Activities/services: Nutrition counseling and education sessions have been conducted on food sources of iron for more than 200 iron-deficient students at the University Health Services Manoa. In addition, health professionals at the Pacific Coast College Health Association were presented with the concept of iron bioavailability from food as one of the key factors related to iron deficiency. By including in these presentations our findings that clams, legumes, and spinach are not good sources of bio-available iron, health professionals indicated they will refrain from recommending these foods to patients to help treat or prevent iron deficiency. Products: Over this last year 15 tips relating to iron deficiency, including the iron content of the foods we tested, were produced for the Got Nutrients - Nutritional Essentials for Health website (www.manoa.hawaii.edu/gotnutrients). Presently there are over 500 subscribers to Got Nutrients daily tips and these include individuals from 13 colleges and universities nationwide. In addition, 2 Health Options columns were published in the Honolulu Star Advertiser by Joannie Dobbs and Alan Titchenal. These columns were titled "Finding iron-rich foods can be a difficult task" on Monday, December 7, 2009 (www.nutritionatc.hawaii.edu/HO/2009/433.htm) and "Hair loss in women has contributing factors" on Tuesday, June 15, 2010 (www.nutritionatc.hawaii.edu/HO/2010/447.htm). Products - A scientifically referenced "Iron Essentials for Health and Nutrition" website has been designed - www.gotnutrients.net/iron/. At this point, the home page and database structure has been developed. The site was designed so that any of the co-investigators can easily update information to keep it current. In addition to dietary iron sources and factors affecting bioavailability, this website includes avenues to address general information about the general functions of iron, iron requirements, differences between non-anemic iron deficiency and anemia, and iron overload conditions. PARTICIPANTS: Michael A. Dunn, PD - Supervised all aspects of the project, directed and trained graduate students who conducted the experiments, and collaborated with all co-PDs in their respective roles. Joannie Dobbs, Co-PD - Identified and reviewed prominent government and private-sector websites that ranked food-sources of iron and identified clams, beef, legumes, tofu, and spinach as being among the top-10 ranked foods; assisted PD and graduate students in purchasing and preparing foods for analysis; continued the development of a website to disseminate our findings to consumers and stakeholders; and disseminated findings to health professionals, students, and clients. Halina Zaleski, Co-PD - Assisted the PD with statistical analysis of experimental data. Yong Soo Kim, Co-PD - assisted the PD with caco-2 cell culture methods development and training graduate students in cell culture techniques. Jennifer Lai, MS graduate research assistant - helped purchase and prepare clams, legumes, tofu, spinach, and beef for the experiments, conducted laboratory assays to measure iron content, heme iron content, and bioavailability of the products tested; continued the training of new graduate students to assist in the project. Tony Perfecto, MS graduate research assistant - Assisted Jennifer Lai with food preparation and laboratory assays. TARGET AUDIENCES: After publication in peer-reviewed journals, the target audience will be government websites such as MyPyramid.com and the Dietary Guidelines for Americans site (health.gov/dietaryguidelines) and the healthcare professionals and general public that uses them. Groups that would most benefit from valid website information on iron include: women of reproductive age and their children, vegetarians, individuals that donate blood, the elderly, athletes and military personnel. Local efforts include a newspaper column as well as daily tips on obtaining essential nutrients found in both the Honolulu Star Bulletin newspaper and Got Nutrients website:www.gotnutrients.net/index.cfm. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Change in knowledge outcomes about clams as a source of iron: We learned more about why clams should not be recommended as an excellent food-source of iron on websites. Firstly, clams were found to contain very little heme iron, a type of iron found in meats, poultry and fish and known to be absorbed more efficiently than all other types of iron in foods. This finding is important because the recommended dietary allowance (RDA) for iron states that at least 10% of the daily iron intake should come from heme iron. Clams cannot provide this heme iron and should not be recommended as a replacement for other sources of heme iron in the diet. Secondly, the bioavailability of the iron in clams was strongly inhibited by co-consumption of black tea. This indicates that polyphenols in tea, coffee, wine, and many fruits and vegetables can inhibit iron absorption from clams. Change in knowledge outcomes about legumes, tofu and spinach as sources of iron: We learned that, despite their being listed among the top 10 food-sources of iron on most websites, these plant products are not good sources of iron. All of the following products purchased at local supermarkets were found to contain less that 1.8 mg iron per reference amount (serving): edamame, chickpeas, lima beans, kidney beans, soft tofu, firm tofu, and spinach. Only soybeans and lentils contained 1.8 mg iron per reference amount, enough iron to be called a "good" iron source by the FDA's definition. However, the amount of bio-available iron in all of these products was low. One serving provided less than one third the amount of bio-available iron as a serving of beef or 9.8 mg of ferrous sulfate. Co-consumption of vitamin C is often recommended as a means to increase iron bioavailability from plant products, but we found that vitamin C had no effect on bioavailability from tofu, and only a small enhancing effect in soybeans.
Publications
- No publications reported this period
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: Activities/services- Health professional staff at the University Health Services at Manoa were presented with the results of our research. As a result, they no longer recommend clams to patients to help treat or prevent iron deficiency, and will communicate to colleagues that clams should not be recommended as an iron source. In addition, nutrition counseling for more than 100 iron-deficient students, faculty and staff have been conducted on food sources of iron. Products - A scientifically referenced "Iron Essentials for Health and Nutrition" website has been designed - www.gotnutrients.net/iron/. At this point, the home page and database structure has been developed. The site was designed so that any of the co-investigators can easily update information to keep it current. In addition to dietary iron sources and factors affecting bioavailability, this website includes avenues to address general information about the general functions of iron, iron requirements, differences between non-anemic iron deficiency and anemia, and iron overload conditions. Dissemination - Over this last year, 20 tips relating to iron deficiency in iron content of foods were produced for the Got Nutrients - Intergenerational Nutritional Essentials for Health website (www.manoa.hawaii.edu/gotnutrients). Got Nutrients tips are also published in the Honolulu Star Bulletin daily. In addition, a column titled "Iron plays an important role for the thyroid" was published in the Honolulu Star Bulletin Health Options Column By Joannie Dobbs and Alan Titchenal on March 21, 2009. PARTICIPANTS: Individuals: Michael A. Dunn, PD - Supervised all aspects of the project; directed and trained graduate students who obtained the experimental data on iron content and iron bioavailability of foods; supervised the writing of all publications; and collaborated with all co-PDs in their respective roles. Joannie Dobbs, Co-PD - Identified and reviewed websites that discuss iron deficiency and promote dietary iron sources; ranked food sources that are promoted as good iron sources on websites and identified clams as the #1 ranked food; assisted PD in purchasing and preparing clams for analysis; initiated the development of a website to disseminate our findings to consumers and stakeholders; and disseminated findings to health professionals, students, and clients. Halina Zaleski, Co-PD - Assisted the PD with statistical analysis of experimental data. Yong Soo Kim, Co-PD - assisted the PD with caco-2 cell culture methods development and training graduate students in cell culture techniques. Jennifer Lai, MS graduate research assistant - conducted the food preparation and most laboratory assays to measure iron content and bioavailability of the clam products tested; has been training new graduate students to assist in the project. Tony Perfecto, MS graduate research assistant - Assisted Jennifer Lai with food preparation and laboratory assays. Training and professional development: The project formed the basis for the MS thesis of Jennifer Lai (her thesis is listed under the publications section of this report. The project is currently forming the basis of the ongoing MS thesis research of Tony Perfecto. TARGET AUDIENCES: Target audiences include the general public, university health professional students and practicing health professionals. In addition, groups that would most benefit from valid iron information include: children, women of reproductive age, vegetarians, individuals that donate blood and the elderly. Efforts include a newspaper column as well as daily tips on obtaining essential nutrients found in both the Honolulu Star Bulletin newspaper and Got Nutrients website: www.manoa.hawaii.edu/gotnutrients. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
A total of 45 individual and 5 focus group surveys were conducted to assess what iron deficient individuals know about choosing good food sources of iron and where or how they get their information. The conclusions were that individuals primarily used five sets of search terms in an effort to find iron-related information on the internet. Terms used included: iron deficiency, iron anemia, good iron sources, iron vegetarian, and hospital iron food. The top 100 sites we retrieved for each set of search terms were screened, and 350 unique websites and 426 unique web pages were identified. More than 150 unique foods representing all food groups were recommended by these databases making it nearly impossible for individuals to make informed judgments about good iron sources. Clams were identified as the food most often recommended as the best source of iron, but there is little information in the literature on the iron content or the bioavailability of iron in clams. We, therefore, evaluated the iron content and iron bioavailability of a variety of clam products. Change in knowledge - Contrary to existing databases, several clam products were shown to have low iron content and/or iron bioavailability, and should not be recommended to consumers as a good food source of iron. Canned and pouched minced clams in particular were low in iron content (less than 1.1 mg per 100g) and iron bioavailability relative to beef or iron sulfate. Although fresh clams contained higher amounts of iron (2.5 to 5.6 mg/100g), the amount of bioavailable iron was as low as that provided by the minced clams. In contrast, whole baby canned and pouched clams contained high levels of iron (17 to 53 mg per 100g) and provided amounts of bioavailable iron similar to beef and iron sulfate. However, some whole baby clam samples were very high in iron (40 to 53 mg per 100g) and most contained high levels of aluminum (up to 96 mg per 100g). Since it was not possible for a consumer to identify the high iron/aluminum clam products, we cannot recommend whole baby clams as a food source of iron because of the potential to consume greater than the tolerable upper limit of iron and aluminum. Change in actions - Dr. Dobbs will not promote clams in the media as a iron source and she will correct misconceptions about clams in classes for health professionals. In addition, Health Professionals at the University Health Services at Manoa will advise patients and colleagues that clams should not be used as an iron source. Change in conditions - behavioral changes to improve nutrition and health were made.
Publications
- Lai, J., Dobbs, J., and Dunn, M.A. (2009) Clam Products as Food Sources of Iron: Iron Content and Bioavailability Relative to Beef. Annals of Nutrition and Metabolism 55: Supplement 1 (abstract), 19th International Congress of Nutrition, October 4-9, 2009, Bangkok, Thailand
- Lai, J. 2009 Are clams a good source of iron Evaluation of total iron content and iron bioavailability in processed clam products using the in-vitro digestion caco-2 cell method. M.S. Thesis. Univ. Hawaii, Manoa. 144p.
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