Willy,

The 24-Hour Recall method can be used to estimate the average intake of a group, although larger sample sizes are generally needed, and, depending on level of precision desired, inter-subject variability needs to be accounted for (Gibson 1990). I think your sample of 300 is sufficient here, although see item 2, below.  

Consider the following two options as a means of maximizing the accuracy and reliability of your results. 

1) The USDA recommends a using a technique called the "5-Step Multiple-Pass Approach"  (http://www.ars.usda.gov/Services/docs.htm?docid=7711). This is multi-step process for each 24-Hour Recall, with different emphases for each pass: 1. quick list of foods from that day, 2. double-check on commonly forgotten foods, 3. time and eating occasion for each food, 4. details about food eaten, such as preparation, and 5. final probe about forgotten eating events such as snacks.

2)  Another way to improve reliability of the 24-Hour Recall method is to better account for intra-individual variability by collecting three interviews over three separate days - ideally 2 week days and one weekend day (Lee and Nieman 2007).  If only two days are possible, collect one during the week and one during the weekend.  Collecting only one interview can still provide important dietary data for your sample, but the reliability of the data is reduced. 

Best of luck.

Gibson RS. 1990. Precision in Dietary Assessment. In: Principles of Nutritional Assessment. New York: Oxford University Press. p. 97-166.

Lee RD, and Nieman DC. 2007. Measuring Diet. In: Nutritional Assessment. New York: McGraw-Hill. p. 77-114.

yes, definitely. I think for a sample size of 300 single 24 hour administration is very valid tool to assess nutrient intake. Even in less sample it is found equivalent to a semi-quantitative food frequency questionnaire. You can refer following for the same.

http://www.ncbi.nlm.nih.gov/pubmed/7808063

http://www.ncbi.nlm.nih.gov/pubmed/7808063

If your primary objective is to assess nutrient intakes then a single days 24 hour recall is not enough. To assess nutrient intake by 24 hour diet recall, you will need to take the recall for at least 3 non-consecutive days including 1 Sunday for better representation. You may even consider FFQ in addition to the 24 hour recalls since considerable variation in eating pattern may occur during pregnancy.

I agree with Dr Ekbote - an FFQ would be more representative as long as you include a list of food items that is appropriate to your study location, population and aims, or you might consider a 3 or 4 day diet diary, with plenty of help on reporting of portion sizes, recipes etc. You could consider asking your participants to take photos if possible of their meals and snacks to provide additional information.

I suggest for food record rather than food recall. It'll cut the time of recalling consumed food, even more precise, and will be easier for participants.

Hi a 24 hour recall will not be appropriate as the previous study cited above (1994) clearly shows that there is a poor correlation with 24 recall and the consumption of iron and folic acid in the diets of patients tested. Iron and Folic acid are 2 very essential nutrients in the diets of pregnant women and if the nutritional assessment in these women are being tested then a longer follow up is required even a 3 or 5 day recall ould be better.

Agreed on a 3 day recall.

I agree. A 3 day record (a prospective food record not a retrospective recall) including a weekend day would be more representative, although it won't account for seasonal variation. You may also need to determine how you will account for portion size and preparation methods as these will affect nutrient intake. You might even consider some of the readily available Apps such as MyFitnessPal that have large data banks and are user friendly. 

A 3-day recall including one weekend is preferred and will give better result.

Although studies suggest that dietary intake based on a R24h is a reliable measure of the usual food consumption of population groups (see Biasiotis et al), at least two R24h, one on the intake of a weekend day and another a day from Monday to Friday, would be more suitable. Include also a QFA, would bring the usual consumption information.

Basiotis PP, Welsh SO, Cronin FJ, Kelsay JL, Mertz W. Number of days of food intake records required to estimate individual and group nutrient intakes with defined confidence. J Nutr. 1987;117:1638-1641.

Dodd KW, Guenther PM, Freedman LS, Subar AF, Kipnis V, Midthune D, Tooze JA, Krebs-Smith SM. Statistical methods for estimating usual intake of nutrients and foods: A review of the theory. J Am Diet Assoc. 2006;106:1640-1650.

No method is particularly precise. However, if you are evaluating nutrient intake of a group, a food frequency questionnaire or a multiple pass 3d 24 hour recall would be appropriate. The ASA24 is freely available and is a less expensive option since it is a self- 24 hour recall. I would not do less than 3 days of recall in a pregnant population to establish nutrient adequacy since intake may be highly variable day to day. 

http://epi.grants.cancer.gov/asa24//

Willy - Perhaps consider a 24 hr recall and adding a questionnaire for usual intake of key foods and beverages. Consider the short vitamin D and calcium FFQ. You may want to ask how their nutrition changed upon realizing they were pregnant. There may be several short questionnaires that can help you achieve the results you need.

Consider the link below as a start.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257701/

Dear Willy,

Every thing depends on what you want and what you have. The quality of the result from 24 hr recall varies a lot by skills of the interviewer, database to handle the recalls, the complexity of diet of subject population, etc. Also depending on how muxh other references are available in your country or for the population of interest would affect the value of your 24 hr recall.

For usual intake, FFQ along with 24 hr recalls are recommended. However, it is possible only when you have FFQ developed and validated for the population of interest for a specific purpose such as nutrient(s) you are interested in. Hence, I do not think it is possible to have FFQ with your 24 hr recall planned at this moment. But I would like to encourage you to work on 24 hr recall if you have trained staff to deal with because information on nutrient intake of pregnant women is not only important but also rather scarce.

Good Luk! 

Willy,

The 24-Hour Recall method can be used to estimate the average intake of a group, although larger sample sizes are generally needed, and, depending on level of precision desired, inter-subject variability needs to be accounted for (Gibson 1990). I think your sample of 300 is sufficient here, although see item 2, below.  

Consider the following two options as a means of maximizing the accuracy and reliability of your results. 

1) The USDA recommends a using a technique called the "5-Step Multiple-Pass Approach"  (http://www.ars.usda.gov/Services/docs.htm?docid=7711). This is multi-step process for each 24-Hour Recall, with different emphases for each pass: 1. quick list of foods from that day, 2. double-check on commonly forgotten foods, 3. time and eating occasion for each food, 4. details about food eaten, such as preparation, and 5. final probe about forgotten eating events such as snacks.

2)  Another way to improve reliability of the 24-Hour Recall method is to better account for intra-individual variability by collecting three interviews over three separate days - ideally 2 week days and one weekend day (Lee and Nieman 2007).  If only two days are possible, collect one during the week and one during the weekend.  Collecting only one interview can still provide important dietary data for your sample, but the reliability of the data is reduced. 

Best of luck.

Gibson RS. 1990. Precision in Dietary Assessment. In: Principles of Nutritional Assessment. New York: Oxford University Press. p. 97-166.

Lee RD, and Nieman DC. 2007. Measuring Diet. In: Nutritional Assessment. New York: McGraw-Hill. p. 77-114.

No matter what time frame you choose, your answer will be meaningless. This is because you will feed them the wrong food. Most of humanity eats indigestible junk, and you are one of them.

I have similar idea to that of ,Daniel C. Benyshek.

24-hr dietary recall can give give you a reasonable information of the nutrient intake if conducted correctly. It is better if you make it twice to include a week day and a weekend day. Every method has its limitations.

The 3 days diet record is the most appropriate method if you want to assess macro and micro nutrients intake providing that you have a well trained assistants making sure that the records are filled on time and complete. and as mentioned by Daniel C. Benyshek "collecting three interviews over three separate days - ideally 2 week days and one weekend day (Lee and Nieman 2007)". Some times we use it in clinical settings to assess our patients intake and also in research and it gave a good picture of an average nutrients intake.