Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages

Abstract

The effects of different polyphenol-containing beverages on Fe absorption from a bread meal were estimated in adult human subjects from the erythrocyte incorporation of radio-Fe. The test beverages contained different polyphenol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (Matricaria recutita L.)), vervain (Verbena officinalis L.), lime flower (Tilia cordata Mill.), pennyroyal (Mentha pulegium L.) and peppermint (Mentha piperita L.), or complex polyphenol polymerization products (black tea and cocoa). All beverages were potent inhibitors of Fe absorption and reduced absorption in a dose-dependent fashion depending on the content of total polyphenols. Compared with a water control meal, beverages containing 20–50 mg total polyphenols/serving reduced Fe absorption from the bread meal by 50–70 %, whereas beverages containing 100–400 mg total polyphenols/serving reduced Fe absorption by 60–90 %. Inhibition by black tea was 79–94 %, peppermint tea 84 %, pennyroyal 73 %, cocoa 71 %, vervain 59 %, lime flower 52 % and camomile 47 %. At an identical concentration of total polyphenols, black tea was more inhibitory than cocoa, and more inhibitory than herb teas camomile, vervain, lime flower and pennyroyal, but was of equal inhibition to peppermint tea. Adding milk to coffee and tea had little or no influence on their inhibitory nature. Our findings demonstrate that herb teas, as well as black tea, coffee and cocoa can be potent inhibitors of Fe absorption. This property should be considered when giving dietary advice in relation to Fe nutrition.

Fe, Ca and Mg contents in selected fast food products in Poland

“…Cheeseburgers, pizza without meat, french fries and apple pie mostly contain non-hem iron, the bioavailability of which can be enhanced by, for example, consumption together with a salad, fruit or vegetable juice (containing vitamin C and b-carotene), or with meat [30][31][32]. Drinking tea, coffee or milk together with food providing Fe should be avoided, because both phenol compounds and calcium reduce the bioavailability of this element from food [33][34][35][36].…”

Quercetin (=2-(3,4-Dihydroxyphenyl)-3,5,7-trihydroxy-4H-1- benzopyran-4-one) Glycosides and Sulfates: Chemical Synthesis, Complexation, and Antioxidant Properties

“…Moreover, polyphenols can take part in reductive mechanisms of iron uptake from ferritin or soil oxides [16]. They can, however, decrease the absorption of iron from the diet [17]. Finally, polyphenols, especially flavonoids, can prevent ROS generation (e.g., the Fenton reaction) by sequestering iron ions under inactive complexes [18] although pro-oxidant effects have been evidenced, depending on the flavonoid structure and iron concentration.…”

“…It may thus be assumed that the OHÀC(4') and OHÀC(3') are primarily involved in H-atom transfer reactions to DPPH and/or that each OH group strongly facilitates Habstraction from the other by stabilizing the corresponding radical by a combination of electronic and H-bonding effects. The favourable role of the catechol group in the antioxidant (H-atom-donating) activity can be rationalized from in vacuo semiempirical quantum-mechanics calculations (AM1 parametrization) with simple phenols such as 3,4-dihydroxybenzaldehyde (16), 4-hydroxy-3-methoxy-benzaldehyde (17), and 3-hydroxy-4-methoxybenzaldehyde (18), in which the aldehyde moiety models the electron-withdrawing enone moiety of flavones and flavonols (Scheme 4). The rotamer of 16 in which the most acidic OH group (OHÀC(4)) acts as the H-bond donor (16a) is more stable by 0.8 kcal mol À1 than the one in which OHÀC(3) is the donor (16b), in agreement with a more stable intramolecular H-bond (3.7 vs. 2.8 kcal mol À1 ).…”

White tea consumption slightly reduces iron absorption but not growth, food efficiency, protein utilization, or calcium, phosphorus, magnesium, and zinc absorption in rats

“…However, the polyphenols found in tea may also interact with other compounds in the diet, such as proteins and some mineral elements, particularly iron, lowering their availability. The antinutritional effect of tea polyphenols has previously been assessed in black and green tea [4,8,11,16,22,26,28], but not in white tea. The present study evaluates the antinutritional effects of two different doses of white tea administered for two different lengths of time, and is, to the best of our knowledge, the first study published that looks at white tea consumption and evaluates its antinutritional effects.…”

“…On the other hand, most polyphenols from tea, such as tannic acid, gallotannin, catechin, and proanthocyanidin, might possess antinutritional properties since they form insoluble complexes with proteins and certain mineral elements in the lumen of the gastrointestinal tract, causing decreased absorption of these nutrients, particularly non-heme iron [4,8,11,16,29]. reduce food digestibility [13].…”