PEN eNews 10(11) November 2020
PEN
® eNews is a monthly e-newsletter shared with the global PEN Community and created to help dietitians position themselves as leaders in evidence-based nutrition practice. In addition, users of the PEN System will find articles on the new evidence, resources and features available and how to maximize one's use of PEN.
The Lung Cancer Knowledge Pathway is Updated!
The Lung Cancer Knowledge Pathway is updated. Do you know the answer to these questions?
- How much fruit is recommended daily to reduce the risk of cancer in current and former smokers?
- Does eating retinol (vitamin A)-containing foods reduce the risk of lung cancer?
- Is the consumption of foods containing vitamin C associated with a reduced risk of lung cancer in current smokers, former smokers or for those that have never smoked?
- Does arsenic in drinking water increase the risk of lung cancer?
- Is taking beta-carotene supplements recommended for current and former smokers?
- Does alcohol intake impact lung cancer risk?
For answers to these questions and for additional information, see the links below:
Looking for more information related to cancer? There are:
10 Knowledge Pathways
87 Practice Questions
194 Handouts
Enter the search term “cancer” in the PEN® Search and check out the results!
Want to know what else is new and updated? Bookmark these pages:
New Knowledge Pathway Content (Knowledge Pathways, Practice Questions, Summary of Recommendations and Evidence, Practice Guidance Toolkits, Backgrounds)
Tools and Resources.
Thyroid and Soy - What is the Latest?
The Question
Does the consumption of soy products (food or supplements) affect thyroid function among adults?The Recommendation
While free triiodothyronine (fT3) and free thyroxine (fT4) have generally not been affected by soy product (food or supplement) intakes, increases in TSH have been observed in some groups, particularly among those with pre-existing subclinical hypothyroidism or among those consuming soy products longer than three months. There is currently no recommendation for the general public regarding modifying soy product intakes for thyroid function and there is no dose response data available. However, it should be noted that soy consumption can interfere with the absorption of levothyroxine medication. Users of this medication should follow the advice provided by the prescribing physician or pharmacist regarding how best to take their medication.
To see the full practice question, including the Evidence Summary, Remarks, Evidence Statements, Rationale and References, click here.
PEN® Content: What is on the Horizon
With 204 PEN Knowledge Pathways, more than 1100 Practice Questions and research constantly being published, the PEN Team is kept busy updating content and adding new content. Wondering what is going to be added to the PEN System or updated in the near future?
Check out the following:
New, Revised and/or Expanded Pathways Under Development
New
Being Updated/Revised
Allergenic Disease
Autism
Breast Cancer
Carbohydrate Counting
Cystic Fibrosis
Dementia
Food Safety
Food Skills
Functional Foods/Nutraceuticals
Gastrointestinal System - Pediatrics/Paediatrics
Gastrointestinal System - Pediatrics/Paediatrics: GERD/GORD
Gastrointestinal System - Pediatrics/Paediatrics: Infant Colic
Gerontology
Heart Failure
Lactose Intolerance
Low Carbohydrate and Diabetes
Malnutrition
Menopause
Neutropenia
Nutritional Implications of Cancer
Organic Foods
Pregnancy
Reactive Hypoglycemia
Telehealth
Vegetarianism
If you are an individual subscriber and wish to receive notifications when specific content is updates, sign up for PEN Content Alerts.
Open Access to COVID-19 Content Continues
Although the Open Access to the entire PEN® System is now closed, we continue to make COVID-19 information, Trending Topics and PEN® eNews available to all with no PEN subscription or access credits required:
If you are interested in continuing your access to the entire PEN System and you are not a current subscriber, please view the different subscription options available at:
https://www.pennutrition.com/signup.aspx. Revenue from PEN subscriptions is reinvested in the system to keep the content up-to-date and constantly growing while positioning you on the leading edge in your practice. The PEN System does not accept industry revenue or advertising.
We hope you'll be an active member of our PEN community and stay connected with us:
Stay Safe,
The PEN Team
Surprising Findings: Spilling the Tea
I thought I was seeing double! As an avid tea drinker, an article investigating tea consumption with cancer risk caught my eye. But, spoiler alert! This “surprising finding” isn’t specifically about tea or cancer risk. During a perusal of the literature, I had stumbled upon not one, but two meta-analyses assessing tea consumption and cancer risk in observational studies published within months of each other in the same journal by different authors. While repetition and validation are important aspects of the scientific process, it is not every day that articles appearing to address the same research question and objectives are published in the same journal so close together, unless there is a debate on the topic. So, I was curious to investigate “why?”
My investigation had two main questions.
First Question: What did the authors find and did the findings between the two articles differ?
To provide a bit more background, both research teams meta-analyzed observational findings examining the association of black tea, green tea or total tea intake on the risk of any type of cancer (1,2). Neither study reported excluding articles from their analyses based on the type of participants being studied, the duration of the follow up or the setting of where the study took place.
Surprisingly, overall, there appeared to be little evidence to support an association between tea drinking with cancer risk; however, the findings did differ between the two articles.
Kim and colleagues were the first to publish their research showing a significant inverse association between tea consumption and the risk of oral cancer (1). Inverse associations with other types of cancer were also reported; however, the authors noted the findings were not supported by consistent or convincing evidence.
Zhao and colleagues showed, except for an inverse association between lymphoid neoplasms with green tea intake, no consistent associations were observed between tea consumption and cancer risk when there was more than one cohort, either for assessment of the highest compared to the lowest tea intake nor in dose-response analyses (2).
Second Question: What could have led to these differences?
A key difference was in the methodology, specifically the type of meta-analysis conducted. Kim and colleagues conducted an umbrella review (i.e. a meta-analysis of meta-analyses, which syntheses information from all systematic reviews and meta-analyses on a given topic) (1), whereas Zhao and colleagues meta-analyzed individual prospective cohorts (2).
An umbrella SRMA has been called one of the ‘next-generation’ SRMAs being touted to “raise the bar and help shape a new generation of more reliable evidence synthesis” (3). While an umbrella SRMA certainly has the potential to enable an efficient method for higher level synthesis of evidence allowing for detection associations, effects, uncertainties and knowledge gaps, its strength is still dependent on the type of data available and included. Kim and colleagues present one example of an umbrella SRMA acknowledging limitations based on the types of studies included (1). Specifically, the authors reported inclusion of systematic reviews with both cohort and case-control studies, and due to the potential biases that may affect case-control studies, such as recall and selection bias, recommended further analysis of only prospective studies.
Zhao and colleagues met this call as they purposely included only prospective cohort studies in their analyses to reduce potential bias (2). As well, they provided separate analyses by tea type (black, green, total) (2), which had not been done by Kim and colleagues (1).
Additional methodological comparisons consisted of the umbrella SRMA including only English language publications (1), whereas the articles included by Zhao and colleagues had no language restriction (2). Only the Zhao article reported publicly registering their study protocol (2), which allows for greater transparency. Given the observational nature of both studies, a causal relationship between tea and cancer could not be inferred in either case. Despite limitations, both articles should be acknowledged for their strengths, specifically their comprehensive designs affording an overview of at least 25 cancer sites using standardized SRMA methods.
These studies serve as a reminder of the importance of assessing the strengths and limitations of research methods. One of the earliest research lessons I received was to read and critically assess the methods of a paper first (even before the abstract!). This advice highlights the importance of research methodology and continues to stay front of mind as I ponder the next article over a cup of tea.
If you were hoping to learn more about tea and/or cancer, don’t worry the PEN
® System has you covered! Check out this
content.
Written by:
Stephanie Nishi RD, MSc, PhD(c)
PEN Evidence Analyst
References
- Kim TL, Jeong GH, Yang JW, Lee KH, Kronbichler A, van der Vliet HJ, et al. Tea Consumption and Risk of Cancer: An Umbrella Review and Meta-Analysis of Observational Studies. Adv Nutr. 2020 Jul 15:nmaa077. doi: 10.1093/advances/nmaa077. Epub ahead of print. PMID: 32667980. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/32667980
- Zhao LG, Li ZY, Feng GS, Ji XW, Tan YT, Li HL, Gunter MJ, Xiang YB. Tea Drinking and Risk of Cancer Incidence: A Meta-Analysis of Prospective Cohort Studies and Evidence Evaluation. Adv Nutr. 2020 Oct 1:nmaa117. doi: 10.1093/advances/nmaa117. Epub ahead of print. PMID: 33002099. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/33002099
- Ioannidis J. Next-generation systematic reviews: prospective meta-analysis, individual-level data, networks and umbrella reviews. Br J Sports Med. 2017 Oct;51(20):1456-1458. doi: 10.1136/bjsports-2017-097621. Epub 2017 Feb 21. PMID: 28223307. Link available from: https://pubmed.ncbi.nlm.nih.gov/28223307
PEN® International Guideline Collections
Many knowledge pathways include a tool called the International Guideline Collection. These collections gather all of the clinical practice guidelines on a specific topic from our global partners and around the world.
There are over 20 International Guideline Collections. Here are the latest ones that are new or have been updated:
Looking for the entire list of International Guidelines Collections, look no further than
here.
PEN eNews
November 2020 Volume
10 (11)
A Publication of the PEN® System Global Partners,
a collaborative partnership between International Dietetic Associations.
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