PubMed Food Problem: Cruciferous Vegetables

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To do a PubMed search for cruciferous vegetables that includes such species as Radish and Arugula, each species must be done separately.

By Eric Rumsey, Janna Lawrence and Xiaomei Gu

In order to do successful searches for cruciferous vegetables in PubMed, it helps to know exactly what “cruciferous” means, which makes it easier to understand what vegetables are considered “cruciferous” and the botanical relationships among them. We have discussed these topics in a companion article.

In general, cruciferous vegetables are considered to be any plants in the family Brassicaceae that are edible. Most of these, especially the more popular ones (cabbage, broccoli, cauliflower, brussel sprouts) are in the genus Brassica. A few others are in other genera in the family, the most notable being Radish (Raphanus), Daikon (Raphanus), Arugula (Eruca), Horseradish (Armoracia), White mustard (Sinapis), Garden cress (Lepidium) and Wasabi (Wasabia). With most edible members of the family Brassicaceae being in the genus Brassica, then, searching for that genus works well for most cruciferous vegetables. But without including the MeSH terms for all of the other edible genera in the family, there is no easy way to do a comprehensive search for them as a group.

With edible species in several genera in the Brassicaceae family, it might seem like a way to include all of them would be to search for the family name, since it’s an explosion that contains all of the genera in the family. We have seen this done by MeSH indexers in some cases, but it has problems. For one thing, the family is very large, containing 372 genera, so searching for the family name can retrieve many inappropriate citations. This is especially a problem because one of the genera in the family is Arabidopsis, a very commonly used research subject in plant genetics, having nothing at all to do with nutrition. Arabidopsis is something like the Drosophila of the plant world. So of course searching for the exploded MeSH term Brassicaceae gets a flood of articles on Arabidopsis; approximately 80% of all articles retrieved from this search are indexed to the narrower term Arabidopsis.

We found another problem in how cruciferous vegetables are treated in PubMed indexing when we looked at sample of 30 articles with “cruciferous” in the title.  Twenty-eight of the 30 articles actually had the phrase “cruciferous vegetables” in the title, but  in about ⅓ of the 30 articles, there was no indexing term at all correlated with the word “cruciferous,” and the indexing term used was just “vegetables,” ignoring the word “cruciferous.” Another problem we found in this sample is that, of the articles that had an indexing term correlated with “cruciferous,” the term that was usually used was the family name, Brassicaceae, which retrieves many non-food-related citations, as discussed above.

Suggestions for improving indexing of cruciferous foods

Because there is currently no way to search for cruciferous foods as a group, we would suggest that NLM should add a new MeSH term <cruciferous foods>. This would not only put all of these foods under one term, it would also provide a term to use for articles that use the term itself in the title or abstract.

Image at top of article is from Wikipedia.

Plant-Based Foods – A Tricky PubMed Search – Revised 2016

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By Eric Rumsey, Janna Lawrence and Xiaomei Gu

As we discussed in an article earlier this year, searching for nutrition in PubMed has improved greatly since NLM brought the subject together in one explosion (Diet, Food, and Nutrition). This ability to search the field of nutrition easily has helped in searching for plant-based foods [PBFs] in some ways. But in other ways, it’s still as difficult as it was when we wrote our 2013 article on the same topic.

The basic problem in searching for PBFs, just as it was before the addition of the new explosion, is that a large proportion of PBFs are not in the Food explosion, but are only in Plants, and not in Food. So the fact that Food is part of the new inclusive explosion doesn’t make it any easier to search for PBFs.

In addition to the fact that most fruits and vegetables are treated as plants instead of foods, another problem in searching for them is that almost all of them are put under their botanical, Latin names, that are not recognizable to most people. Here are some examples, all of which are in the plant-taxonomic branch of the MeSH tree:

  • Kale is Brassica
  • Sweet potato is Ipomoea batatas
  • Plum is Prunus domestica
  • Almond is Prunus dulcis
  • Apple is Malus
  • Cranberry is Vaccinium macrocarpon
  • Strawberry is Fragaria
  • Kidney Beans is Phaseolus
  • Chocolate is Cacao
  • Turmeric is Curcuma

If you’re searching for specific food plants, the Latin botanical MeSH terms are usually not a problem, because when you search for a common name, it’s mapped to the botanical MeSH term (e.g. if you search for Grapes, it maps to Vitis). The problem comes if you want to browse the Plants explosion to pick out the edible plants from the many plants that are not edible, because only the botanical names are listed. The Rose family (Rosaceae) of plants, for example, has several edible species within it. There are 19 genera listed in MeSH in the family, and 6 of them have edible species. But to find them, you have to be able to pick out the genera with edible species (e.g. Malus, Prunus) from the others (e.g. Agrimonia, Alchemilla).

If you’re interested in learning about how to search for PBFs in PubMed, see our companion article, which includes an updated “search recipe,” or hedge.

[Image above is public domain, from WikiMedia]

US Lags Behind The World In Plant-Based Food Research

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Many other countries spend a much larger proportion of their research time and resources on plant-based foods than the United States does.

By Xiaomei Gu, Eric Rumsey and Janna Lawrence

In our explorations of plant-base foods (PBFs) in PubMed, it’s often striking that there are many excellent articles from non-US countries. So we did a survey in PubMed to measure different countries’ authorship of articles on PBFs, and we found that, indeed, several countries have a much higher proportion of their total articles on PBFs than the US.

The chart above shows our data for all PBFs and the charts below show four specific foods or food groups. The charts are based on the percentage of articles from each county, not the total number of articles. So even though the total number of articles on PBFs by US authors may be higher than other countries, the proportion of articles on PBFs is substantially lower. [The charts are from a poster presented at MLA in 2016. For more details on our survey methods, see the poster. The PubMed search strategy used to find plant-based foods in the chart above is described here.]

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Nuts as a Healthy Food: How to Search in PubMed

By Eric Rumsey, Janna Lawrence and Xiaomei Gu

This article is based on a poster presented at the Medical Library Association annual meeting, Toronto, May 2016.

Introduction

Searching for nuts as food is difficult. As with most plant-based foods, MeSH terms for specific types of nuts are in the Plants explosion instead of in the food explosion. Nuts are especially tricky because the MeSH term Nuts is not an explosion, and most articles on specific types of nuts are not indexed to the term Nuts. So it’s necessary to search for specific nuts to retrieve articles on them.

A caveat—As with nutrition topics in general, and plant-based foods in particular, searching in PubMed is complicated, largely because many plant-based substances are used as foods and also as medicines or experimental organisms. A list of articles on specific nut types is likely to contain some articles that are not food-related.

Searching for Nut Types

The general idea of searching for specific types of nuts is simple: Do an OR search that includes the common name and botanical name. In most cases, articles on a specific nut type will be indexed under the botanical name, but using the common name is always a good idea. See the example below for searching walnuts.

walnut [tiab] OR walnuts [tiab] OR juglans [MeSH]

It is necessary to restrict the search for the common names to the title and abstract [tiab] fields because there are many streets in the Address field that are named after nuts (e.g., 975 Walnut St.).

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Image 1. Almonds

 

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Image 2. Walnuts

 

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Image 3. Hazelnuts

 

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Image 4. Cashews

 

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Image 5. Pecans

 

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Image 6. Brazil Nuts

 

Peanuts Are Different!

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Image 7. Peanuts

Peanuts are a special case. Unlike the other nuts here, they grow on herbaceous plants instead of on trees and, as members of the bean family, they are nutritionally more closely related to beans than to other nuts. There is also a separate MeSH term, Peanut Hypersensitivity, dealing with peanut allergies.

Because peanuts are commonly used as experimental plants, many of the articles about them are not related to nutrition. To  focus on nutritional aspects, we suggest incorporating the Diet, Food, and Nutrition explosion into the search:

(peanut [tiab] OR peanuts [tiab] OR arachis [mh])

AND Diet, Food, and Nutrition [mh]

Citations: 2932

EndNote X7 for MAC now works with Microsoft Word 2016

endnote_logoGood news!  EndNote X7 for the Mac now works with Microsoft Word 2016.  When you open the desktop version of EndNote, it should tell you that that there is an update available, but you can also select Check for Updates in the EndNote X7 dropdown menu.  EndNote Basic (the online only version) will also prompt you to install the new Cite While You Write plug-in for Word.  Whether you are using the desktop or online version, you also need to have the latest version of Word 2016  (currently version 15.18) installed.

Once Word and EndNote are both updated, the EndNote Cite While You Write tools should appear as a tab in Word. The first time you launch Word 2016 after updating EndNote, you will be asked to “grant access” to an EndNote .plist file. Simply click Grant Access; you should not be asked this again.

More information about the update, including some troubleshooting in case the tools do not automatically appear in Word, can be found at http://endnote.com/kb/138936.  More information about updating Word, with a more complete explanation about “granting access,” is at http://endnote.com/kb/138936.

If you have questions about EndNote, please contact your Library Liaison or Janna Lawrence.

ClinicalKey, Other Elsevier Resources Undergoing Maintenance, Saturday, August 1

All Elsevier products will be undergoing maintenance on Saturday, August 1, beginning at 5:00 pm central time, until approximately 10:30 pm.

ClinicalKey will still be available, but individual log-ins, used to view PDFs and save content within ClinicalKey, will be unavailable.  HTML views of chapters and articles will still be available.

All other Elsevier resources, including journals and books accessed through the ScienceDirect platform and EMBASE, are expected to be unavailable.

Embase: Tips For Navigating A Powerful & Tricky Resource

By Eric Rumsey
Embase, which we described in an earlier article, is a powerful biomedical database which is comparable to PubMed. Unfortunately, the interface for Embase is rather difficult to navigate, especially for new users. We have created two resources for beginning users:

A 2-page handout: Basic Searching in EMBASE

A slide set that shows the first steps in doing a successful search in Embase: Embase: Use Quick Search To Do Mapping!

A slide set that shows the steps to do a simple search on heart attack and aspirin: Embase Searching- A Basic Tutorial

Searching Nutrition In PubMed & Embase: The Winner Is…

By Eric Rumsey and Janna Lawrence

As we’ve discussed, the big problem in searching for food-diet-nutrition subjects in PubMed is that the subjects are not together in a convenient bundle, as most subject groupings are in PubMed. To get a list of articles that includes food, diet and nutrition, it’s necessary to search each of these areas separately and then bundle them together into one search set.

When we first wrote about the difficulty of searching food-diet-nutrition in PubMed in 2013, we stated clearly that much of problem is caused by the fragmentation of the the relevant MeSH terms. So, jump forward a year. About two months ago, our library got institutional access to Embase.com, sometimes called the “European MEDLINE.” Embase includes all of the articles in MEDLINE, as well as many other articles, and uses its own subject heading system. Because we’ve long been aware that food-diet-nutrition subjects are generally given more attention in Europe than in the US, we thought that the subject might get better treatment in Embase than it does in PubMed. We weren’t disappointed…

A Nutrition explosion that includes Food and Diet

Embase uses explosions to bundle related subjects together, much like PubMed, and, as we were hoping, it does indeed bring food, diet and nutrition subjects together in a convenient bundle – Nutrition. So in the search box, just type in Nutrition/exp to get the nutrition explosion, that will retrieve everything on food and diet as well as nutrition. This is a great advance over PubMed. It becomes easy to combine a subject of interest with food-diet-nutrition, in one simple step. For example, using Embase.com format:

‘Heart disease’/exp AND Nutrition/exp
Neoplasm/exp AND Nutrition/exp
‘Mental function’/exp AND Nutrition/exp

To do equivalent searches in PubMed, it’s necessary to do a hedge/filter search, such we have developed, or to search food-diet-nutrition terms separately and combine these with the subject of interest.

Better treatment of “Food” in Embase

Certainly having the inclusive food-diet-nutrition explosion is the biggest advantage in Embase. But there are other problems in PubMed, especially in the way the Food explosion is treated. In both Embase and PubMed, Food is the largest food-diet-nutrition explosion. There are several difficulties with this explosion in PubMed. An overall complication is that Food and Beverages have a confusing relationship. They are together in one explosion Food and beverages, which is made up of two separate explosions, one for each of the terms. If the user knows enough to search Food and beverages, he/she will get both terms. But if the user searches “Food,” the search will not include beverages. In Embase, beverage is an explosion that’s included in the food explosion, so searching “food” will retrieve articles on beverages.

Several other problems with the Food explosion in PubMed are caused by a lack of detail, in comparison with Embase. Some examples:

  • In PubMed, Fruit is not an explosion, although there are individual fruits included in the Plants explosion, usually under their Latin plant name. In Embase, the fruit explosion has 43 terms under it, 6 of which are themselves explosions.
  • In PubMed, Spices is an explosion with one term under it – Black Pepper. In Embase, the spice explosion has 31 terms listed under it, 4 of which are themselves explosions.
  • In PubMed, specific kinds of red meat, e.g. beef and pork, do not have their own MeSH terms; instead, they’re indexed under the general term Meat. In Embase, the meat explosion contains a red meat explosion, which has 7 terms, including beef and pork.

Related to the lack of detail in the Food explosion in PubMed is that many foods, especially plant-based foods, are not retrieved in a search for “food” because they don’t have specific terms in the Food explosion. We have written some “case studies” of this on chocolate, cranberries, and olive oil, all of which are in the Food explosion in Embase, but not in PubMed. We have also written an article on red meat being difficult to search in PubMed because there is no MeSH term for it; as mentioned above, Embase does have a term for it.

Looking at articles in Embase and PubMed that mention specific foods in the article abstract, it’s almost always the case that Embase’s detailed indexing will include descriptor terms for the specific foods, and PubMed usually will not. Comparison of article indexing is easy to do because Embase provides a “Source” filter, that makes it possible to limit to articles that are included in both Embase and PubMed. Each of the articles retrieved using this filter has a direct link to the citation in PubMed.

PubMed Advantages

The biggest advantage of PubMed, of course, is that it’s free to world. Embase, on the other hand, is an Elsevier product and is only available at institutions that have a subscription.

Another PubMed advantage is its simple Google-like interface, which is certainly more comfortable to most people. Embase uses an older style of interface that may appeal to librarians more than to most users. For anyone with a serious interest in food-diet-nutrition, though, we would say it’s definitely worth learning.

Plant-Based Foods – An Inclusive PubMed Search

This article has been superseded by the following:
Plant-Based Foods – An Inclusive PubMed Search – Revised 2016

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By Eric Rumsey and Janna Lawrence

In our earlier article on searching for plant-based foods (PBF) in PubMed, we suggested that a quick way to search the subject is to combine MeSH plant-related explosions AND our Food-Diet-Nutrition (FDN) hedge. This works quite well, especially for citations after 2002. In that year the Plants explosion was greatly expanded by the addition of several hundred new MeSH plant names. Before that, articles on specific plants were indexed inconsistently. Sometimes they were put under the plant family name, in which case they were included in the Plants explosion, and in other cases they were indexed under other terms like Vegetables, Fruit, or Plants, Edible, that are not in the Plants explosion.

In order to do the most inclusive search for plant-based foods, including citations before 2002, we have created two hedges, to be used for all the years in PubMed. These hedges include other MeSH terms and text-words, to supplement the plant-related MeSH term search strategy that works well after 2002. We have done fairly thorough testing of the two hedges, and we recommend the first hedge for most searches. It uses MeSH terms, and it emphasizes precision, which means that it gets somewhat fewer citations, but the citations are more likely to be on target. For both of the hedges, we’ve combined them in an OR search with the “Plants AND FDN” hedge search mentioned above.

Here’s the first hedge – Recommended for most searches – Emphasizes Precision:

((Plants [mesh] OR Plant Preparations [mesh]) AND (food OR foods OR beverages OR diet OR dietary OR vitamin OR vitamins OR nutrition OR nutritional OR nutrition disorders OR food industry OR nutritional physiological phenomena OR dietary fats OR dietary proteins OR feeding behavior)) OR (Vegetables [mesh] OR Fruit [mesh] OR Cereals [mesh] OR Plants, Edible [mesh] OR Soybeans [mesh] OR Dietary Fiber [mesh] OR Flour [mesh] OR Bread [mesh] OR Diet, Vegetarian [mesh] OR Nuts [mesh] OR Condiments [mesh] OR Vegetable Proteins [mesh] OR Tea [mesh] OR Coffee [mesh] OR Wine [mesh])

[9.5.14. Hedge revised – Number of citations: 294,149]

To use this search, click this link. You can also copy the text above and paste it into the PubMed search box. If you have a personal “My NCBI” account in PubMed, the hedge search can be saved for later use, or it can be made into a search filter. For information on setting up and using saved searches, see here; for more information on filters, see here. Commentary on terms in this hedge (If the “Year introduced” is not given, the term has been in MeSH since its launch in 1966):

  • Vegetables [mesh] Citations: 84411 An explosion that includes about 25 specific vegetables, including Onions, Soybeans, Daucus carota, and Solanum tuberosum. This is a relatively small proportion of all vegetables, which are indexed with their species or family name, in the Plants explosion.
  • Fruit [mesh] Citations: 57179 Notably, this is NOT an explosion. All particular fruit types are indexed with their species or family name, in the Plants explosion.
  • Cereals [mesh] Citations: 73516 An explosion that includes 8 cereals, including Avena sativa, Triticum and Zea mays. This is an important group, since it includes the world’s staple foods–wheat, rice, and corn.
  • Plants, Edible [mesh] Citations: 38945 An explosion that includes several terms elsewhere in this hedge that get more citations when they’re searched separately. The term Plants, Edible by itself gets 5402 citations.
  • Soybeans [mesh] Year introduced: 1986 Citations: 19284 An explosion that includes Soy Foods, Soy Milk, and Soybean Proteins.
  • Dietary Fiber [mesh] Year introduced: 1982(1977) Citations: 13468
  • Flour [mesh] Citations: 3570
  • Bread [mesh] Citations: 3115
  • Diet, Vegetarian [mesh] Year introduced: 2003(1963) Citations: 2537
  • Nuts [mesh] Citations: 2074
  • Condiments [mesh] Citations: 1945 An explosion that includes Spices.
  • Vegetable Proteins [mesh] Year introduced: 1975 Citations: 1515
  • Tea [mesh] Citations: 6904
  • Coffee [mesh] Citations: 4751
  • Wine [mesh] Citations: 7256

Here’s the second hedge – Emphasizes Recall:

((Plants [mesh] OR Plant Preparations [mesh]) AND (food OR foods OR beverages OR diet OR dietary OR vitamin OR vitamins OR nutrition OR nutritional OR nutrition disorders OR food industry OR nutritional physiological phenomena OR dietary fats OR dietary proteins OR feeding behavior)) OR (vegetable OR vegetables OR fruit OR fruits OR cereal OR cereals OR spices OR condiments OR flour OR nut OR nuts OR vegetarian OR soy OR soybean OR soybeans OR bread OR Tea OR Coffee OR Wine)

[9.5.14. Hedge revised – Number of citations: 380,361]

To use this search, click this link, or see instructions above with first hedge. Most of the words used in this hedge are text-word versions of the MeSH terms used in the first hedge. Since this emphasizes “recall” instead of “precision,” it gets more citations than the first hedge. But the citations are less likely to be relevant. We looked closely at citations using the two hedges, and it was easy to see the lesser relevancy of the citations in the second hedge. Most of these, of course, are retrieved because they mention words that are in the abstract (e.g. fruit, vegetables) but which are not assigned as MeSH terms.

A word about searching for older citations

When we first realized that most of the plant name MeSH terms were only introduced in 2002, it seemed like a serious problem. However, as we’ve looked back retrospectively, we’ve come to see that there really wasn’t much research attention given to the subject in the earlier days of MEDLINE, especially before about 1990.

We’ve done detailed work to study this, but in this article we’ll just give a couple of anecdotal examples of what we’ve found. We looked at the number of citations that contain the word “fruit” since 1968, and found that this stayed flat, at about 400 mentions per year, until about 1990. It’s grown fast since then, and in 2013, the word is in about 8000 citations. In another example, we found that there are 70 articles in all of PubMed that have “sweet potato” in the title, and are on human subjects. All but three of these are after 1992; zero citations from 1980-1992 contain the words in the title. So, if it seems like the hedges in this article aren’t finding many citations before 1990, it’s probably because there just aren’t many to be found.

Things improve in the 1990s. It appears, from our retrospective examination of citations on FDN, that as the volume of research on the subject increased, NLM gradually improved the quality of MeSH indexing to accommodate it. The coverage of more prominent plant families improved, and the application of existing FDN MeSH terms became more consistent. So in the 1990s, even before the mass introduction of new MeSH plant terms in 2002, FDN indexing and retrieval was improving.