Bioversity International: research for development in agricultural and tree biodiversity

Improving diets in Vietnam with roots, tubers and bananas

27 Nov 2017

Erin Zettell1 and Jessica Raneri, from Bioversity International, report on how consuming more roots, tubers and bananas, particularly micronutrient-rich varieties, can improve the malnourishment prevalent in northwest Vietnam.

Vietnam’s high prevalence of malnutrition in children and women is contributing to high disease burden, economic insecurity, and political instability.2,3,4 One way to combat this could be to implement roots, tubers, and bananas (RTB) into the agricultural systems. They require few inputs and can provide superior energy and micronutrient yields in comparison to other major food crops. What’s more is that RTB varieties can also be grown under harsh conditions.2,5 

Consequently, we traveled to the Mai Son district of the rural Son La province in northwest Vietnam, where malnutrition and poverty rates are higher than the country’s average, to investigate the role of RTB in the diets of children and women and to see how micronutrient-rich RTB varieties can be integrated to improve their diet’s quality.

We analyzed results of a 24-hour dietary recall (a research method used in nutritional assessment, which asks individuals to recall foods and beverages they consumed in the twenty-four hours prior to the interview) obtained in 2014 where 418 pairs of children aged 12-24 months and women of reproductive age were visited during the wet and dry seasons. We identified the RTB varieties that were being consumed, as well as the dietary patterns (quantities and frequencies of consumption) associated with these crops. What we found was that, across both seasons, around a quarter of the women and children (27 and 24.6%, respectively) consumed 12 different RTB foods from 7 species: banana flower; banana tree trunk; Cavendish banana; carrot; common ripe banana; sweet potato leaves; orange sweet potato tuber; pale yellow sweet potato tuber; unripe banana fruit; vermicelli from Bermuda tuber (noodles made from refined tuber starch); white potato tuber; and white taro tuber.

Although, generally, the micronutrient intake from all foods consumed was slightly higher during the wet season compared to the dry season, there was a higher percentage of RTB-derived micronutrients consumed in the dry season. As a matter of fact, Cavendish banana, banana flower, carrot, pale sweet potato tuber, orange sweet potato tuber and white taro tuber were consumed more frequently during the dry season. 

We also observed that children and women who consumed RTB had higher micronutrient intakes across both seasons and fewer significant differences in quantities of micronutrient intakes between the two seasons.

Harvesting carrots, one of the underutilized root crops, in Mai Son, Vietnam. Credit: Bioversity International/J.RaneriOur results indicated that RTB crops, on average, are a good source of vitamin C and folate and high in vitamin B6 and magnesium during both seasons for children. RTB is also a good source of vitamin B6 and magnesium during both seasons for women. As for vitamin C for women, RTB is a good source during the wet season and high in it during the dry season.* These varying amounts of RTB nutrition contributions between women and children may result from differences in the RTB consumption patterns.

We then used the Optifoods linear programming software application to see whether more micronutrient-rich RTB varieties could improve the diet quality. We created modeled diets modifying Vietnam’s food composition table, which was used for the 24-hour recall analysis, by replacing most of the existing RTB entries with more micronutrient-rich varieties. Collaborating with partners from the HarvestPlus programme, we obtained data on the vitamin A-rich RTB varieties, orange-fleshed bananas and sweet potato, and yellow cassava. Data on other micronutrient-rich varieties was procured from other existing food composition tables available in the Asia. We did not replace RTB types for which we could not identify a more nutritious alternative.

Our modeled diets were based on the current dietary patterns, including frequency and quantity of foods consumed, and include 20% increases in the average portion sizes of RTB. It is important to note that 20% was deemed a realistic average increase in portion sizes, as we have observed that such portion sizes were already consumed in several cases.

We found that these children cannot consume sufficient calcium, iron and zinc within current dietary patterns, even in the most optimal diet model. However, we also found that, it would be possible for them to reach sufficient micronutrient intakes by consuming a larger variety of RTB foods more frequently. Alternatively, the modeled diets with the more micronutrient-rich RTB varieties coupled with increasing the average RTB daily portion size by just 20% would also allow the population to consume the recommended quantities of micronutrients.

Sustainably intensifying and diversifying production systems to include micronutrient-rich RTB varieties into the existing agricultural systems in Mai Son, Vietnam, may increase both the availability and consumption of RTBs. This could ultimately better the conditions of prevalent poor health in the region by improving diet quality with increased micronutrient intake.

* According to FAO Nutrition and Health Claims guidelines, when one serving of a food contributes over 15% or 30% of an individual’s RDA value for a micronutrient, that food is considered to be a “good source of” or “high in” that micronutrient respectively. 

Read more about Bioversity International’s initiative on ‘Healthy diets from sustainable food systems’. 

And see how village health workers in Vietnam are putting nutrition back on the menu. 

This work is carried out in collaboration with the CGIAR Research Program on Roots, Tubers and Bananas and the CGIAR Research Program on Agriculture for Nutrition and Health, and is supported by CGIAR Fund Donors


1. Erin Zettell completed her field placement at Bioversity International headquarters in Summer 2017. She worked together with Jessica Raneri on the 'Healthy diets from sustainable food systems' research initiative.

2. Popkin, B., Thang, N.M., (2003). Child malnutrition in Vietnam and its transition in an era of economic growth. Journal of Human Nutrition and Dietetics. 14:4. 233-244. doi:10.1046/j.1365-277X.2003.00449.x

3. World Bank. 2011. Vietnam - Nutrition at a glance. Nutrition at a glance; Vietnam. Washington DC; World Bank.

4. General Statistics Office. 2011. Child Growth and Malnutrition. Viet Nam Multiple Indicator Cluster Survey. Final Report, 2011. Ha Noi, Viet Nam. Cited in WHO Global Database.

5. Thang, N. M., & Popkin, B. M. (2003). In an era of economic growth, is inequity holding back reductions in child malnutrition in Vietnam? Asia Pacific Journal of Clinical Nutrition. 12:405-10. PMID:14672863.

Photos from top to bottom:

Local variety of purple sweet potato in Mai Son, Vietnam. Credit: Bioversity International/J.Raneri

Harvesting carrots, one of the underutilized root crops, in Mai Son, Vietnam. Credit: Bioversity International/J.Raneri