PEN eNews 12(4) April 2022

Vitamin C and Immune Function: What is the Latest?

Does vitamin C supplementation improve immune function, including preventing or treating the common cold?

Habitual vitamin C supplementation may reduce cold severity and duration and exercise-induced bronchoconstriction symptoms. For the general population, it does not reduce cold incidence or improve asthma outcomes, but an exception may be decreased cold incidence in individuals undergoing brief periods of heavy physical stress (soldiers and athletes). It is unclear whether vitamin C supplements play a role in the prevention of pneumonia.

Treatment with vitamin C after the onset of symptoms does not reduce cold severity or duration and does not improve acute pancreatitis outcomes. For pneumonia, due to the uncertainty of the evidence, it is unclear whether vitamin C supplements provide any additional support in the treatment of pneumonia in children.

Vitamin C supplements of ≤2 g/day have not been associated with adverse effects, except in individuals with severe acute pancreatitis.

Pneumonia
Results from a 2021 Cochrane review reported that due to limited and very low certainty of evidence, it was unclear whether vitamin C supplementation (2 g/day) prevented pneumonia in young adults. For the adjunct treatment of pneumonia in children under five years of age with vitamin C supplements (200 mg/day), results showed a small improvement in the time it took to improve oxygen saturation and respiration rates compared to controls. However, these results should be viewed with a high degree of caution as the evidence was considered of very low certainty due to study limitations (unclear or high risk of bias in most domains), small sample size and imprecise results (wide confidence intervals). Only one prevention study reported on adverse events with vitamin C supplementation and it was found to have uncertain effects on urticaria. More and better studies are required.
Grade of Evidence C

Common Cold
In a Cochrane review, the routine consumption of ≥200 mg/day vitamin C did not reduce common cold incidence in the general population but may have slightly reduced cold duration and severity. However, for athletes and soldiers undergoing brief periods of heavy physical stress, vitamin C supplementation reduced common cold incidence by about half (RR=0.48; 95%CI, 0.35 to 0.64). In adults, high doses of vitamin C (1-8 g/day) after the onset of a cold did not decrease cold duration or severity compared to placebo.
Grade of Evidence B

Asthma/Bronchoconstriction
In a Cochrane review using GRADE analysis, vitamin C supplementation of 0.5 to 5 g/day in individuals with asthma had no effect on:

• symptoms
  Grade of Evidence B

• health-related quality of life
  Grade of Evidence C

• asthma exacerbation.
  Grade of Evidence C

There was no evidence of adverse effects with a dose of 1 g/day. For individuals with exercise-induced bronchoconstriction, 1.5 g/day vitamin C improved asthma symptom scores.
Grade of Evidence C

Acute Pancreatitis
In a small RCT of individuals treated for severe acute pancreatitis, there were no significant differences in organ dysfunction or length of hospital stay between those supplemented with a combination of IV antioxidants (vitamin C, selenium and n-acetylcysteine) and a placebo. The trial ended early when it was discovered that all four individuals who had died during the trial were from the intervention group.
Grade of Evidence C 

Remarks

For individuals wishing to experiment, vitamin C supplements are low cost and have no adverse effects (except in severe acute pancreatitis). A minimum dose of 2 g/day used in the trials is unlikely to be achieved by dietary sources alone.

To see the full practice question, including the Evidence Statements, Remarks, Comments and References, click here.

New Knowledge Pathway Alert! Nutrition and Fertility

The PEN Team is pleased to announce a new knowledge pathway Nutrition and Fertility!

This knowledge pathway has the following practice questions with more on the way:

• Is body mass index (BMI) related to male infertility?

• Do males who consume soy (foods or supplements) have more fertility/reproductive problems than males who do not consume soy?

• Is there a role for antioxidants in the treatment of male infertility? 

Sign up for PEN Content Alerts to find out when the new practice questions are added.

Also, check out the following related knowledge pathways:

• Endocrine and Metabolic - Polycystic Ovary Syndrome
• Pregnancy
• Pregnancy - Hypertension
• Pregnancy - Multi-fetal
• Pregnancy - Nausea and Vomiting/Hyperemesis Gravidarum

The Urogenital System Knowledge Pathway is Updated!

The Urogenital Knowledge Pathway was recently updated. Do you know the answers to these questions?

• Can saw palmetto (Serenoa repens) help alleviate the symptoms of benign prostatic hyperplasia?

• Are there any foods or dietary supplements that can help treat erectile dysfunction?

Click here for the answers and for additional information, including related tools and resources.

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.

We Need Your Expertise: PEN^® Reviewers Needed 

We need reviewers within the next few months for:

• Chronic Obstructive Pulmonary Disease (COPD)
• Metabolic Syndrome
• Musculoskeletal/Connective Tissue Disorders - Fibromyalgia
• Nephrology - Acute Renal Failure; Chronic Kidney Disease

Are you getting locked out of the PEN^® System and Wondering Why?

We have the answer to your question. Read on...

Typically, this happens when a PEN Account is accessed from multiple devices. Have you shared your username and password with someone in the past?  Doing so not only violates the license agreement, but it puts you at risk. You are responsible for any and all activity that occurs under your account that results if you fail to keep this information secure and confidential. 

According to the PEN License Agreement, a PEN Account can’t be accessed concurrently on multiple devices. Sharing your username and password is against the PEN License agreement and can result in losing access to the PEN System. So make sure to sign out of the PEN System every time you’re finished on the website.  

So what happens if your account is used on multiple devices concurrently?

• The first offence: a warning message will appear on the screens and both users will be logged out. The owner of the PEN license will need to review the relevant section of the PEN License Agreement and accept these terms on both devices prior to logging in again. 

• The second offence: a warning message will appear on the screens and both users will be logged out. The PEN account will be suspended for one hour. The owner of the PEN license will once again need to review the relevant section of the PEN License Agreement and accept these terms on both devices prior to logging in again.

• The third offence: a warning message will appear on the screens and both users will be logged out. The PEN account will be suspended for 24 hours and the owner of the PEN license will once again need to review the relevant section of the PEN License Agreement and accept these terms on both devices prior to logging in again.

• The fourth offence: a warning message will appear on the screens and both users will be logged out. The account will be disabled, and the owner of the PEN license will be asked to contact the PEN Team.

You can read the full License Agreement here! 

thank you to our PEN^® volunteers

Canada

Cathy Chenhall
Caitlin Choquette
Adele Gagnon
Julia Ianiro
Mahsa Jessri
Rachael Kearns
Michelle Lee
Madelaine Morrish
Karen Parinas
Monica Storey
Brock Williams
Jessica Wong