Studies on the availability of iron in potatoes

Abstract

1. Iron availability in potatoes and ferrous sulphate was measured in rats in a 10 d balance study and from a single meal using 59Fe and 55Fe as extrinsic labels.2. Dried potato samples were incubated in gastric juice in vitro and the amount solubilized was compared with other foods. The relationship between ascorbic acid content of dried potato and Fe solubilization was examined in vitro.3. In the balance study, the rats absorbed (mean with SE) 15.2 (2.7)% Fe from the diet containing 660 g dried potato/kg and 32.1 (2.8)% Fe from the semi-synthetic diet containing FeSO,. Absorption was higher from the extrinsically-labelled single meal: 49.6 (1.1)% Fe from 5gFe-labelled potato and 62.4 (1.2)% Fe from 5DFeS0,.4. The in vitro experiments showed a much greater solubilization of Fe from potato than from the other foods examined. There was a correlation between Fe solubilization and ascorbic acid content of potatoes (rs 0.76,5. It appears that potatoes contain Fe of moderate availability, possibly higher than most vegetables. They also provide ascorbic acid which may enhance Fe absorption from a meal if present in sufficient quantities. Thus potatoes may make a useful contribution towards the Fe nutriture of the UK population.The amount of iron contributed by potatoes (Solanurn tuberosum) to the average UK daily diet is 6.2% (Ministry of Agriculture, Fisheries and Food, 1980) which is more than any other single vegetable. Main-crop potatoes contain approximately 3 mg Fe/kg and new potatoes 4 mg Fe/kg (Paul & Southgate, 1978) which is lower than most green vegetables, e.g. Savoy cabbage (var., Brussica oleracea) 7 mg Fe/kg and Brussels sprouts (var., Brassica oleracea) 5 mg Fe/kg. However, potatoes are consumed daily and usually in larger quantities than other vegetables. Indeed, people from low-income groups, particularly families with several children consume greater amounts of potato than the national average. Thus potatoes make a small but measurable contribution towards Fe intake and, after liver, bread and canned beans, they are considered good nutritional value for money, contributing 0.3 mg Fe/penny (Ministry of Agriculture, Fisheries and Food, 1980).Since only approximately 10% of total dietary Fe is absorbed, absolute values for Fe intake are meaningless unless accompanied by some indication of availability. The limited number of reports in the literature suggest that the availability of Fe in vegetables is low. For example, Layrisse et al. (1969) found that Fe absorption from spinach (Spinacea oleracea) by human subjects was 1.7%, from black beans (Phuseolus vulgaris) 3.2% and from lettuce (Lactuca sativa) plus tomato juice 5.8%. In comparison, Fe from meat and fish was better absorbed with meat values ranging from 16 to 20%. In order to standardize the results and make them comparable with other studies, ferrous ascorbate absorption was also measured in each individual. The food Fe: ferrous ascorbate values were 0.1 1 for spinach, 0.17 for black beans, 0-3 1 for lettuce, 0-4 for fish and 1.3 1 for veal. T...

Iron and zinc concentration of native Andean potato cultivars from a human nutrition perspective

“…Past studies have suggested that due to considerable amounts of ascorbic acid in potato, Fe availability is moderately high. 12 However, further information is still needed on the content of enhancers (ascorbic acid and carotenoids) and inhibitors (polyphenols and phytates) of Fe absorption, and in vitro or feeding studies should be conducted to estimate the bioavailability of Fe from potatoes as a staple food and as a dietary component are warranted to assess the potential impact on human nutritional status.…”

“…Significant levels of Fe and Zn 7 -11 and moderate availability of Fe 12 have been reported for potato, but broad genetic resources have not been surveyed to provide knowledge of the potential for enhancing Fe and Zn concentration through selection or variety improvement. Of particular interest are the many diverse native potato varieties that are cultivated in the high Andes where Fe deficiency rates are high.…”

Analysis of phytate in raw and cooked potatoes

“…In cereals the sum of InsP 6 and InsP 5 needed to be reduced below 0.5 mmol/g (0.033% phytate) on a dry weight basis in order to substantially increase the solubility of iron in the absence of iron absorption enhancers such as organic acids (Svanberg et al, 1993). The ascorbic acid content of potatoes helps to solubilize its iron (Fairweather-Tait, 1983), but the availability of iron to rats from extrusion-cooked potatoes was only 35.5% compared to 59.9% for extrusion-cooked maize (Fairweather-Tait et al, 1987). Lucarini et al (2000) found the dialyzabilities of iron and zinc from potatoes were 13.6% and 34.7%, respectively.…”

CONTENIDO DE HIERRO Y ZINC EN VARIEDADES Y CLONES MEJORADOS DE PAPAS (Solanum tuberosum L.) DE BOLIVIA

“…Niveles significativos de Fe y Zn y moderada disponibilidad de Fe fueron reportados en papa (True et al, 1978, Casañas et al, 2003, Fair Weather-Tait, 2003) y en Perú se reportó una concentración media de 4,7 mgkg -1 de Fe y 3,5 mgkg -1 de Zn en cultivares de papa (Ortiz, 2010). En nuestro estudio, hemos encontrado concentraciones medias de Fe más altas tal como se observa en la Figura 1.…”

“…Con los niveles observados en este estudio, las mujeres y niños de las comunidades donde se realizaron las colectas podrían incrementar su ingesta de Fe significativamente a través del consumo de la variedad Chota Ñawi. Estudios anteriores sugirieron que debido a los niveles altos de ácido ascórbico (promotor de la absorción de Fe) y niveles bajos de ácido fítico (inhibidor de la absorción de Fe) en papa, la biodisponibilidad de Fe es moderadamente alta(Fair Weather-Tait, 2003). Sin embargo, para que la variedad Chota Ñawi esté disponible y sea utilizada a gran escala se requiere desarrollar un programa más organizado de producción de semilla de calidad.…”