Writing in Food Chemistry, the researchers from the National Institute of Nutrition warn that a better understanding of bioavailability is ‘essential’ in populations that have a diet primarily dependent on plant based foods.
The team, led by K. Madhavan Nair, argue that in order to gain a fully balanced diet, and fight widespread issues of malnutrition, the use of food synergies in which certain foods or nutrients increase the bioavailability of others is vital.
“Countries with predominantly plant based diets need to prioritise on enhancing bioavailability rather than content,” they urge, noting that better methods and standardisation for screening of bioavailability, and biomarkers to demonstrate the synergistic effects of foods are needed.
“The potential implications of such a food synergy in a habitual diet are large, in terms of improving micronutrient status at individual and population level,” Nair and colleagues suggested.
In the review, the team noted an array of research showing that the inclusion of certain foods can increase uptake and bioavailability of others.
“Due to the low bioavailabilities reported for iron, provitamin A, vitamin D and zinc, it is imperative to explore beneficial food synergies to enhance and if possible, overcome the factors which negatively affect bioavailability from plant based diets,” they said.
They cited ‘strong evidence’ for an effect of including vitamin C rich foods and non-vegetarian foods in enhancing the bioavailability of iron. Furthermore, they noted that stable isotope studies done in adolescents have also shown the inclusion of 100 grams of guava in a habitual meal had doubled the iron absorption.
For other micronutrients, they noted that fat has been found to be synergistic for vitamin A absorption, while red wine and protein have been suggested for zinc absorption and effect of fat has been touted as a way to influence vitamin D bioavailability.
However, to Nair et al warn that designing such evidence based food synergies not only requires a detailed understanding the physiology of digestion, absorption and the interactions of micronutrients with the dietary ligands – but also requires robust high throughput micronutrient bioavailability screening methods.
“Techniques of measuring bioavailability are cumbersome but an integral part of efforts to enhance bioavailability of iron, zinc and vitamin A,” they noted. “Using these techniques several food synergies have been identified but rely on the context for its efficacy. Efforts therefore need to revolve around standardization of food synergy as a strategy for reducing micronutrient under nutrition in countries dependent on plant foods.”
Indeed, the Indian team suggested that effectiveness trials are required to test whether the food synergies would sustain the test of time.
“Food based strategies including the food synergies envisaged for enhancing micronutrient bioavailability is a promise for future as a sustainable solution to micronutrient deficiency in population subsisting on plant based diets,” they team concluded.
“However, any food synergy has to be relevant and acceptable to the end user.”
Source: Food Chemistry
Published online ahead of print, doi: 10.1016/j.foodchem.2016.09.115
“Food synergies for improving bioavailability of micronutrients from plant foods”
Authors: K. Madhavan Nair, et al