Soluble and insoluble fractions from nopal (Opuntia ficus) cladodes improve postprandial glycaemic regulation: a crossover randomized study in healthy volunteers

Abstract

Background and objectives: Type 2 diabetes has been increasing all over the world. A healthy diet, including particular functional foods is an effective strategy to prevent this form of diabetes. Nopal (Oputia ficus) is a cactus plant that, according to traditional medicine, has antidiabetic properties. The objective of this research was to examine the effects of different fractions of nopal cladodes on postprandial glycaemic regulation in healthy volunteers.
Methods: Nopal cladodes flour was separated by centrifugation into two fractions (a water insoluble and a soluble fraction). The fractions were incorporated into two different test breads, i.e. insoluble fraction bread (INB) and soluble fraction bread (SNB), and evaluated with respect to acute glycaemic properties in 17 healthy subjects with normal body mass index, applying a randomized cross-over study design. The effects on glycaemic and insulinaemic responses were compared with the responses after a control product, which composed of a similar bread lacking the nopal fractions (white wheat bread, WWB). The products were characterized with respect to starch and dietary fibre content. In addition, starch hydrolysis index (HI) was determined with an in-vitro method in order to predict glycaemic index (pGI),and elucidate possibly underlying mechanisms on postprandial glycaemia.
Results: Results regarding glycaemic regulation show that insoluble nopal fractions had a beneficial effect on postprandial glucose regulation. Consequently, the incremental area under the postprandial blood glucose curve (iAUC) after INB was significantly reduced compared to after intake of the WWB during the time periods 0 – 45 and 0 – 60 minutes (p < 0.05). In addition, the iPeak value, i.e. the individual highest incremental peak concentrations, was significantly lowered after INB compared to WWB (P < 0.05). Regarding the postprandial insulin secretion, both SNB and INB lowered the postprandial iAUC compared to the WWB during the time period 0 – 45 and 0 – 60 minutes (P < 0.05). On the other hand, only the INB significantly reduced the insulin iPeak value compared to WWB (P < 0.05). In terms of HI, INB had lower HI and pGI compared to WWB and SNB. Also, INB exhibited highest total, soluble and insoluble dietary fibre contents.
Conclusion: The INB promoted lower postprandial glucose and insulin response, while SNB showed beneficial effects only on postprandial insulin secretion. The beneficial effects of nopal on glycaemic regulation might be to some extent explained by the dietary fibre content, especially the INB. However, with respect to the improved postprandial insulin economy observed after the SNB, additional mechanisms are probably involved.

Popular Abstract

Type 2 diabetes (T2D) is a chronic condition that causes the rise in sugar level in the blood. There is a growth in the prevalence of T2D associated with metabolic syndrome, globally. Diabetes is one of the world’s leading cause for death, and it is highly related to lack of exercise, personal lifestyle and poor food consumption. Moreover, diabetes is a costly disease, it affects not only the patients, but also the public health systems. The focus was on the identification of possible methodology to be adapted to reverse the unhealthy trend. One of the most important factors to decrease this trend is the diet. Therefore, there is need for more products of specific health properties within this area.
Nopal is one of the amazing plants that can help in the prevention of T2D. It is a domestic species of the cactus, originally from Mexico. This cactus plant also plays an important role in traditional medicine for the treatment of diabetes. The majority of studies on nopal is focusing on the anti-diabetic effects in patients suffering from T2D. Would it then be possible to prevent T2D onset of the disease? A previous study on nopal found that it can lower glycaemic regulation in heathy humans. Also, there are studies showing that dietary fibre is one important factor in nopal that imparts beneficial effects on glucose regulation. The findings led to further concerns on mechanisms behind the physiological effects of nopal. Therefore, the next step of investigation was to figure out the type of fibre involved in the preventable effects. Thereafter, dietary fibre (soluble and insoluble dietary fibre) was focused on, in this study.
Different nopal fractions (soluble and insoluble nopal fractions) were studied. The effect of the postprandial blood glucose regulation after consuming breakfast breads containing different faction was evaluated in healthy humans. First, a fractionation of dietary fibres was performed in order to separate the soluble and insoluble nopal fractions. These fractions were then mixed into bread mixtures for meal study investigations. All breakfast breads studied possessed the same amount of available starch. The breads contained different nopal fractions and was compared with control bread (without any nopal fraction). The healthy volunteers were asked to consume the product and the blood samples were collected to measure the postprandial blood glucose and insulin levels.
The observations from the study showed that the effect on lowering postprandial blood glucose levels were imparted only by the insoluble nopal fraction. On the other hand, both nopal fractions resulted in a reduced insulin secretion. It is important to consider the other components in the nopal fractions in further investigations. However, it can be concluded that both fractions can give a beneficial effect on glycaemic regulation and it can be one of the healthy food choices in the market to prevent the human population from T2D.

• author: Deenissai, Wanussavee
• supervisor: Anne Nilsson
• organization: Food Technology and Nutrition (M.Sc.)
• course: KNLM01 20201
• year: 2020
• type: H2 - Master's Degree (Two Years)
• subject: Medicine and Health Sciences
• keywords: Nopal cladodes, Glycaemic regulation, Randomized cross-over study, Dietary fibre, Hydrolysis index, Applied nutrition, Food chemistry, Industriell näringslära, Livsmedelskemi
• language: English
• id: 9027897
• date added to LUP: 2020-09-15 09:40:50
• date last changed: 2020-09-15 09:40:50