The analysis of the food consumption survey shows that the daily diet did not provide sufficient amounts of micronutrients such as iron and vitamin A for women in reproductive age. Indeed, based on the median intake, diets contributed to only approximately one third of iron requirements (WHO RNI, 
), and two thirds of vitamin A and B2 requirements, and more than 80% of zinc and vitamin B1 requirements. This support that integrated strategies to increase the micronutrient intake of women in reproductive age have to be considered. Amongst them, food fortification has been identified as a cost-effective and important intervention to reduce micronutrient deficiencies 
and is under consideration by the Vietnamese government.
The study also shows that rice, vegetable oil and flavoring powders were widespread, with more than 90% of women of reproductive age consuming them daily. This make these foods relevant food vehicles for micronutrient fortification 
As shown by the calculations based on fortification levels of these food vehicles and their consumption by women, fortification of oil with vitamin A will significantly contribute to increasing the intake of vitamin A by one fourth of the RNI. The process of fortifying vegetable oil with vitamin A is well established 
. Assuring an adequate vitamin A status for women before and during pregnancy and lactation is essential and 14% of the Vietnamese women in reproductive age had a marginal vitamin A status 
. Moreover, it is recognized that during lactation, maternal status or intake of vitamin A strongly affects the amount of vitamin A in breast milk 
. Therefore increasing vitamin A status of women should have an impact on infants and young children which are especially at risk for vitamin A deficiency as demonstrated in the recent study indicating a marginal vitamin A status in half of Vietnamese children 
. Increasing vitamin A intake of women is particularly crucial as WHO no longer recommends vitamin A supplementation post-partum as a public health intervention for the prevention of maternal and infant morbidity and mortality 
. In addition, according to the micronutrient study we conducted (personal communication 
), more than 50% of the women were vitamin D deficient (below 50 nmol/L 
) and more than 30% had insufficient (circulating 25(OH)D between 51–74 nmol/L) vitamin D status 
. Thus the addition of vitamin D to vegetable oil should be considered if the high prevalence of vitamin D is confirmed as a public health problem in Vietnam.
Rice was consumed daily by all women with a median consumption exceeding 300 g per day. Fortifying rice with iron, zinc and folic acid as proposed will provide 40% of daily iron requirements and 30% of folate requirements. This is particularly important for women in reproductive age that are planning on having a baby. Indeed, several studies have shown that iron stores at conception are a strong predictor of maternal iron status and risk of anemia later in pregnancy 
. Moreover, it is very difficult to replenish depleted iron stores once pregnant, particularly for poor women who have less access to and less knowledge of supplements. An adequate folate status is also very important for women of reproductive age especially before conception and during early pregnancy to prevent the risk of neural tube defects (NTD) 
. Our study carried out in 2010 shows that half of these Vietnamese women have low iron stores and the same proportion a marginal folate status 
. Another recent study among women living in Hanoi and Hai Phuong Provinces indicated that 60% had a suboptimal folate status 
. These results support the relevance to increase their iron and folate intakes. Fortification of rice has been proven to be effective in improving iron status for children between 6 to 13 years of age in India when fortified rice provides 17 to 19 mg iron of micronized ferrous pyrophosphate daily 
. Fortification of rice with folic acid in Vietnam would provide 136 µg/day of folate to women. In North America, daily intake of 140 µg folic acid from fortified wheat flour, corresponding to 233 µg folate, was shown to have a similar impact on folate status as daily supplementation with 400 µg folic acid (667 µg folate), when taken during the preconception period and given over a sufficient period of time 
. Moreover, it has been demonstrated in South Africa and the United States that large scale fortification of wheat flour with folic acid prevents neural tube defects 
Regarding zinc, dietary intake data indicated that despite zinc intakes covering approximately 80% of zinc RNI, more than 50% of women had a zinc intake lower than 9 mg/day which is below WHO RNI of 9.8 mg/day. This would explain the high prevalence of zinc deficiency in the Vietnamese women (67%) based on measurement of plasma zinc 
. Moreover zinc intakes were calculated assuming a bioavailability of less than 30% (low bioavailability) 
. However, the Vietnamese diet is based on rice, green vegetables, white meat (pork and chicken) and green tea and consequently rich in phytates and polyphenols. Consumption of red meat, where zinc is the most bioavailable, is low 
. This would suggest that the bioavailability of zinc from traditional Vietnamese diet was probably lower than expected.
Rice fortification would provide 15% of zinc requirements and flavoring powder only 2%. In Thailand, seasoning powder fortified with zinc (5 mg), iron (5 mg), vitamin A (270 µg), and iodine (50 µg) per serving enhanced levels of hemoglobin, zinc, and iodine in 569 preschoolers and adolescents 
. This shows that fortification standards of flavoring powder in Vietnam could be revised by considering adding other micronutrients and increasing their contents taking into account the cost and potential organoleptic issues. Moreover, an impact study has to be carried out before any decision can be taken. Increasing the zinc fortification of rice could also be considered.
Fish and soy sauces were consumed by one third of the wealthiest women and by two third of the women in the lowest two socioeconomic categories. Iron fortification of fish sauce (13) and soy sauce 
have been proven to be efficient in women in randomized controlled trials. In Vietnam, iron deficiency and anemia were significantly decreased and almost disappeared in approximately one year by the regular consumption of fortified fish sauce (5 gFe/L) freely used for traditional cooking and eating practices 
. The current standards for fish sauce fortification recommend a dose of 2.5 mg iron as NaFeEDTA to avoid coloration and iron precipitation 
. This lower quantity may decrease the impact on iron status but NaFeEDTA is known to enhance the absorption of both the intrinsic food iron 
and iron used in other fortified food and may have a beneficial effect on overall iron absorption from the diet. Since sauces are often consumed with rice and vegetables, fortified sauces may support additional iron absorption from these foods.
Wheat flour is widely fortified around the world with multiple micronutrients such as iron, zinc and folic acid and could provide, in the case of Vietnam, 36% of the RNI for folate and 16% for zinc but only 4% for iron in women who consume wheat flour. Unfortunately wheat flour consumption is not widespread in Vietnam, with only 19% of the extreme poor population and 39% of women consuming wheat flour regardless the socioeconomic groups, and therefore limiting the impact of wheat flour fortification nationwide.
The risk of excess intake from a multiple food fortification strategy depends on the combination consumed daily and varies with the micronutrient. More than 55% of households were consuming the following combinations on a daily basis: vegetable oil-sauces-flavoring powder (56.6%), vegetable oil-sauces (60.2%), vegetable oil-flavoring powder (84.8%) or vegetable oil-rice (91.5%). Only about one fourth of the population was found to consume wheat flour with another food. If fortified rice is distributed through the open market, for women who consume all food vehicles at the 75th
percentile level, the five food vehicles could provide 68.9% of the WHO RNI for iron, 100.8% of the WHO RNI for folic acid, 50.4% of the WHO RNI for zinc and 44.4% of the WHO RNI for vitamin A. The tolerable upper limits (UL) for nutrients are the highest level of nutrient intake at which no adverse effects occur. According to The United States Food and Nutrition Board of the Institute of Medicine the UL for zinc is 40 mg, 45 mg for iron, 3,000 µg retinol equivalent for vitamin A and 1,000 µg for folate for adults 
. Even when all above mentioned food vehicles are fortified and the women are eating as described in , the median consumption of 12.3 mg of zinc, 26.4 mg of iron, 441.4 µg vitamin A as retinol activity equivalent (from diet and fortification) and 280 µg folate per day for a woman (from fortification) are all well below the upper limits. Those intakes also stay under the UL for a woman who consumes all the above fortified foods at the 75th
percentile level (13.9 mg of zinc, 31.6 mg of iron, 528 µg vitamin A as retinol activity equivalent (from diet and fortification) and 403 µg folate per day for a woman (from fortification).
Finally, this fortification strategy has little probability of impacting negatively the populations living in mountainous areas, where malaria issues could remain. For instance, we have demonstrated that based on a median intake of these fortified foods, Vietnamese children less than 5 years of age will ingest from 4.7 mg to 9.9 mg of iron per day depending on the age group 
. Those doses are not considered as a high iron dose which could stimulate the growth of pathogenic bacteria 
. Moreover, a recent Cochrane review 
concluded that routine iron supplementation should not be withheld from children living in countries where malaria is prevalent when regular malaria surveillance and health services were available (the case in Vietnam). Therefore, fortification should not be seen as threat.
This study shows that Vietnamese women of reproductive age had a diet that did not allow meeting recommended dietary requirements for iron, zinc and vitamin A. However, preventing iron, vitamin A and other micronutrient deficiencies is crucial especially during periods of high rice and/or food prices and when less money is spent on vegetables, fruits, dairy products, eggs and meat 
, leading to a shift away from preformed vitamin A 
, heme iron, zinc and folic acid rich products. Based on consumption of staple foods and condiments by women in reproductive age, it can be concluded that fortification of oil with vitamin A would improve their vitamin A status. Fortification of rice and wheat flour with iron, zinc and folate could significantly contribute to increase the intakes of these micronutrients. Rice fortification is the most promising action as rice is daily consumed by the Vietnamese population but it may require a couple of months or even years before its implementation at the national level. Currently, strategies aiming at introducing fortified rice through village rice millers are being piloted. On the other hand, the impact of fortifying wheat flour would be probably limited due to its low consumption. Meanwhile, aside from rice fortification, fortification of fish and soy sauces with iron, that has been proved to be efficient, has to be sustained and the feasibility of fortifying flavoring powders with several micronutrients needs to be investigated.