Sugar intake in India: The estimation of dietary intake using the stable isotopic biomarker method of carbon isotope ratio

Globally rapid changes have occurred in diet patterns due to the nutrition transition. These have resulted in massive shifts in diet intake including that of added sugars. Conventional subjective methods of dietary assessment although very useful, still have limitations in determining accurate intakes of sugar due to measurement errors that occur. An objective method with the use of the stable isotopic technique of determining the carbon isotope ratio (13C/12C) or CIR shows promise as a suitable biomarker of sugar intake. Generally, the plants which use the four carbon mode for photosynthesis, that is C4 plants, express a higher amount of stable isotope 13C.

In countries using cane sugar as a predominant source of added sugar, the validity and specificity of the CIR could be high provided usage of corn containing processed foods are not high. Thus, in India using the total CIR may work as meat intakes are also not as high as in the developed countries, while in other countries a better method will be to use CIR-ala which is expensive compared to estimation of total CIR. But both the methods need to be tested across several populations and developed further for use as an appropriate biomarker as up till now studies have been conducted mostly in the US.

Thus, the primary objective of this study is to assess the utility of a biomarker to assess added sugar intake in India. Additionally, sugar intake  will also be assessed based on dietary recalls. An Interviewer administered  24-hour dietary recall will be collected on  â€œ7 non consecutive days over a period of a month “which will include 2 weekend recalls to get the intake of added sugar as well as meat intake using the database and software developed at the Division of Nutrition, St John’s Research institute.  The Secondary objective is to validate the total energy intake obtained through 24-hour dietary recalls with the stable isotopic technique of doubly labelled water to test the accuracy of the recall data collected.

To test the utility of the CIR biomarker, healthy adult subjects will be recruited, their blood and breath samples will be collected to determine 13C values. If possible, a hair sample will also be taken as per a standardized protocol. On a sub-sample, the stable isotopic method of doubly labelled water (DLW) will be used to obtain total energy expenditure (TEE) and to correct for bias in energy intake obtained through the multiple 24-hour dietary recalls. BMR will also be measured. Thus, through this study we will be able to demonstrate the suitability of a biomarker for estimating added sugar intake which is more relevant in the present world with global rates of non-communicable disease increasing rapidly.