Phytic acid content may affect starch digestibility and glycemic index value of rice (Oryza sativa L.)

Abstract

BACKGROUND: Phytic acid (PA) is an anti-nutrient present in cereals and pulses.It is known to reduce mineral bioavailability and inhibit starch-digesting -amylase (which requires calcium for activity) in the human gut. In principle, the greater the amount of PA, the lower is the rate of starch hydrolysis. It is reflected in the lower glycemic index (GI) value of food. People leading sedentary lifestyles and consuming rice as a staple food are likely to develop type 2 diabetes. Hence, this study was planned to understand how PA content of different rice varieties affects the GI. RESULTS: Rice Khira and Mugai which had very low PA (0.30 and 0.36 g kg −1 , respectively) had higher GI values and -amylase activity, while Nua Dhusara and the pigmented rice Manipuri black rice (MBR) which had high PA (2.13 and 2.98 g kg −1 , respectively) showed low -amylase activity and GI values. This relationship was statistically significant, though a weak relationship was found for the pigmented rice. Expression levels of MIPSI, IPKI and GBSSI markedly increased in the middle stage of grain development in all of the six genotypes having contrasting PA and GI. Maximum expression of MIPSI and IPKI was observed in Nua Dhusara and MBR (which had high PA) while that of GBSSI was observed in Khira and Mugai (with higher GI) at middle stage showing a negative correlation between PA and GI. CONCLUSIONS:The data indicate that high PA content in rice might have an adverse effect on starch digestibility resulting in slower starch digestion in the human gut and consequently low glycemic response.

A single nucleotide substitution in the SPDT transporter gene reduced phytic acid and increased mineral bioavailability from Rice grain ( Oryza sativa L.)

“…The variation of PA among the rice cultivar was between the highest and the lowest was 7.9‐fold (Figure 1). The range is very much similar with our earlier findings where PA range from 3.0 to 21.3 g/kg in the non‐pigmented rice (Kumar et al., 2020). A similar range of PA (8.2–32.3 g/kg) depicting 3.93‐fold variation was reported in different rice genotypes (Lee et al., 2015).…”

A Review of Phytic Acid Sources, Obtention, and Applications

“…The consumption of high-phytic-acid diets has also been linked to changes in blood glucose response. [87] Phytic acid, due to its binding ability, can chelate Ca 2+ ions, which are a co-factor for α-amylase, but can also bind to certain amino acids in proteins, thus inhibiting digestive enzymes. Such effects may result in slower starch digestion leading to a lower glycemic response (consequently, high-phytic-acid diets are usually linked to a lower glycemic index).…”

“…Such effects may result in slower starch digestion leading to a lower glycemic response (consequently, high-phytic-acid diets are usually linked to a lower glycemic index). [87,88] Phytic acid intake has been linked to lower blood glucose levels and improved insulin response, both in rodents and humans. [14,89] In diabetic mice fed a diet containing 0.5% and 1.0% phytic acid, a significant fasting glucose levels reduction occurred.…”

Glycemic index values of traditional Kenyan foods: the missing link in the effectiveness of dietary approach in the prevention and management of diabetes mellitus in Kenya

“…The GI of foods can however be manipulated in various ways to suit the needs of people suffering from diabetes mellitus. For example the GI has been found to vary depending on the nature of carbohydrates 20 , dietary fiber, 21 , 22 , 23 , other macronutrients present in the diet 21 , 24 , 25 , presence of micronutrients 24 , preparation, processing and storage 20 , 26 , 27 , botanical origin and variety 17 , 18 , 28 , 29 , 30 , 31 , presence of phytochemical 28 , 32 as well as an accompaniment to the staple or mixing different foods into meals 18 , 19 .…”