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J Nutr. 2016 May;146(5):970-5. doi: 10.3945/jn.115.223693. Epub 2016 Mar 30.

In Rwandese Women with Low Iron Status, Iron Absorption from Low-Phytic Acid Beans and Biofortified Beans Is Comparable, but Low-Phytic Acid Beans Cause Adverse Gastrointestinal Symptoms.

Author information

1
GroundWork, Crans-près-Céligny, Switzerland; nico@groundworkhealth.org.
2
GroundWork, Crans-près-Céligny, Switzerland;
3
Department of Medical Biology, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Huye, Rwanda;
4
Council for Agricultural Research and Analysis of Agricultural Economics, Montanaso Lombardo, Italy;
5
International Food Policy Research Institute, Washington, DC; and.
6
Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland.

Abstract

BACKGROUND:

Phytic acid (PA) is a major inhibitor of iron bioavailability from beans, and high PA concentrations might limit the positive effect of biofortified beans (BBs) on iron status. Low-phytic acid (lpa) bean varieties could increase iron bioavailability.

OBJECTIVE:

We set out to test whether lpa beans provide more bioavailable iron than a BB variety when served as part of a composite meal in a bean-consuming population with low iron status.

METHODS:

Dietary iron absorption from lpa, iron-biofortified, and control beans (CBs) (regular iron and PA concentrations) was compared in 25 nonpregnant young women with low iron status with the use of a multiple-meal crossover design. Iron absorption was measured with stable iron isotopes.

RESULTS:

PA concentration in lpa beans was ∼10% of BBs and CBs, and iron concentration in BBs was ∼2- and 1.5-fold compared with CBs and lpa beans, respectively. Fractional iron absorption from lpa beans [8.6% (95% CI: 4.8%, 15.5%)], BBs [7.3% (95% CI: 4.0%, 13.4%)], and CBs [8.0% (95% CI: 4.4%, 14.6%)] did not significantly differ. The total amount of iron absorbed from lpa beans and BBs was 421 μg (95% CI: 234, 756 μg) and 431 μg (95% CI: 237, 786 μg), respectively, and did not significantly differ, but was >50% higher (P < 0.005) than from CBs (278 μg; 95% CI: 150, 499 μg). In our trial, the lpa beans were hard to cook, and their consumption caused transient adverse digestive side effects in ∼95% of participants. Gel electrophoresis analysis showed phytohemagglutinin L (PHA-L) residues in cooked lpa beans.

CONCLUSION:

BBs and lpa beans provided more bioavailable iron than control beans and could reduce dietary iron deficiency. Digestive side effects of lpa beans were likely caused by PHA-L, but it is unclear to what extent the associated digestive problems reduced iron bioavailability. This trial was registered at clinicaltrials.gov as NCT02215278.

KEYWORDS:

biofortification; iron; lectins; phaseolus vulgaris; phytic acid; phytohemagglutinin; stable isotope technique

PMID:
27029940
DOI:
10.3945/jn.115.223693
[Indexed for MEDLINE]

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