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Nutrition and Dietetics: KNH 404

Best bets for finding research

The databases listed below are some recommended options for tracking down resources to use in your literature review. If you need a refresher on how to best use them, contact me! (Although if you're looking for consumer-related research, I highly recommend reaching out to one of our amazing business librarians.)

Boolean and other operators

Operators are symbols or words that, when combined with search terms, help to either limit or expand your searches. They are important tools for streamlining the search process, but they can be tricky to use correctly and effectively. Here are some common operators and general rules for using them.


Boolean operators

Boolean operators are used to define the relationship between search terms. They can be used to broaden or narrow a set of search results. There are three common Boolean operators: AND, OR, and NOT. It's good practice to capitalize Boolean operators because some databases require it.

AND is used to join words or phrases when both (or all) the terms must appear in the items you retrieve.

This search query would return a much smaller set of records, and the items found would be more specific to your research question. If you are retrieving too many records, try adding another search term with the Boolean Operator AND.

animated Venn Diagram of AND boolean search

OR is used to join synonymous or related terms, and instructs the search tool to retrieve any record that contains either (or both) of the terms, thus broadening your search results.

The OR operator is particularly useful when you are unsure of the words used to categorize your topic or if information on your topic is even available. If you are retrieving too few records, broaden your search by adding a synonym with the Boolean Operator OR.

animated Venn diagram of OR boolean search

NOT is used to exclude a particular word or combination of words from your search results.

If you are retrieving many records that are unrelated to your topic, try using the NOT operator to eliminate a word. This should be done cautiously, because as well as deleting the unwanted items, such a search will also eliminate records that discuss both the relevant topic as well as the unrelated topic.

animated Venn diagram of NOT boolean search




Truncation is used to search all terms that begin with a common stem. Databases tend to be very literal in interpreting your queries, and, for example, won’t return plurals of words if you just type in the singular form (some search systems are capable of doing this automatically, but you can’t assume). If a term you are searching has variants with the same beginning but various suffixes or endings, use truncation to capture all these. The symbol most commonly used for this is an asterisk. For example:

comput* = computer, computing, computation…

Use the asterisk to replace the last few letters of the word. The asterisk means “any character(s) (or none) can be here.” Be careful where you truncate – in the above example, truncating back to comp* would give back a mess of different things (e.g., competition), while compute* would eliminate some of the relevant variants.

Be careful with this technique! It can backfire pretty easily. Do not try to truncate short words like cat or rat, as you’ll bring back too much irrelevant stuff, like catastrophe. Instead search on the particular variants you need, e.g. cat OR cats. Also note that you cannot truncate “backwards” – computers* isn’t a very useful construct, as no other words begin with “computers”.


Phrase Searching

In many databases it is possible to search for sets of words immediately adjacent to each other, i.e. phrase searching. How this works depends on the database. In some, typing two or more words together, e.g. house cat, implies searching for the words together. In other search tools (including Web of Science, and Google), searching on the two words means the same as a Boolean AND search, e.g. house cat is the same as house AND cat; while putting the phrase in quotation marks demands the terms be searched as a phrase, e.g. “house cat”. Consult the database help, or try these possibilities and see what you get.

Best practice is to use quotations around the phrase you want to search. Most databases will recognize this as a phrase search, even if it doesn't require it, and you'll develop a good habit for the databases that do require it.


The examples below from the Biology Department at Davidson College offer some guidance about the proper way to paraphrase. 

Original Text

“Few laboratory creatures have had such a spectacularly successful and productive history as Drosophila. It first entered laboratories about 1900, revealed its talent for experimental genetics to Thomas Hunt Morgan and his students at Columbia University in the early 1910s, and after some ups and downs in status is still going strong almost a century later."

-- from Kohler, R.E. 1994. The Lords of the Fly. The University of Chicago Press, 321 pages

Example 1

Bad paraphrasing. The phrasing in this one is copied almost exactly from the original.

Despite some ups and downs in status, nearly a century after the fly revealed its talent to Thomas Hunt Morgan and his students, Drosophila genetics research continues its spectacularly successful history (Kohler, 1994).

Example 2

Bad paraphrasing. The sentence and paragraph structure is far too similar to the original.

No model organism has been so amazingly useful and effective as the fruit fly. The fly came on the scene as an experimental tool at the beginning of the 20th century, was adopted by Thomas Hunt Morgan and his Columbia pupils at Columbia University around 1910, and (despite some fluctuations in attention paid to it) is still a widely used experimental system (Kohler 1994).

Example 3

Bad paraphrasing. The sentence structure is better, but the overall structure of the paragraph is still to similar to the original.

Drosophila is model organism with a rich and useful legacy. Upon arriving on the scene at the turn of the century, the fruit fly soon became the organism of choice for Thomas Hunt Morgan and his Columbia University pupils. Despite fluctuations in status, fly research is still central to the progress of genetics (Kohler, 1994).

Example 4

Good paraphrasing. It captures the main idea of the original paragraph and doesn't borrow the structure or phrasing.

Thomas Hunt Morgan and colleagues at Columbia University were among the first to use the fruit fly Drosophila as a model organism, adopting it as an experimental system around 1910. Since then, the popularity of the fly has waxed and waned somewhat, but the breadth and depth of current research indicates that Drosophila continues its legacy as an incredibly important research tool (Kohler, 1994).

Need a refresher on searching?

This series of short videos will show you a few useful techniques you can use to improve your literature searches. You can also access the full playlist on YouTube using the link below. 


Get to Full Text with Find It!

Most literature indexes do not have the actual journal articles included within them.  Instead, these indexes just contain information about the article, e.g. titles, authors, abstract.

When you find an article of interest in an index, click the "Find It" button by that entry to get to the full text.  If we have a subscription, "Find It" will provide a link to the journal article. (Or if we have the print, it will provide a link to the catalog with the location and call number.)

Find it button

(A few databases, like Academic Search Complete, include full text for some articles. These databases may allow you to search only for articles available in full text, but be aware that you are only searching a small portion of the articles we actually subscribe to.)

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Ginny Boehme

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