Clinical Updates
Filter:   By Product Type  |  By Date   

Vitamin C
Vitamin C Blunts Exercise Benefits -- (3/26/2019) If you are trying to build muscle with resistance exercise, go easy on vitamins C and E, according to a recent study. Get the details in the Concerns and Cautions section of the Vitamin C Supplements Review.
Vitamin C for Blood Sugar Control -- (2/12/2019) High-dose vitamin C was found to help control blood sugar levels in people with type 2 diabetes in a recent study. For details, see the What It Does section of the Vitamin C Supplements Review. Also see our latest Top Picks for vitamin C.
Vitamin C and Kidney Damage -- (12/9/2018) High doses of vitamin C can cause kidney stones and damage kidneys. People with certain diets or medical conditions may be more prone to these problems. Get the details, including those of a recent case, in the Concerns and Cautions section of the Vitamin C Supplements Review.
Vitamin C and Prostate Cancer -- (9/22/2018) Does taking vitamin C reduce the chance of developing prostate cancer? Find out what studies are showing, including one reported this month, in the What It Does section of the Vitamin C Supplements Review. (Also learn about vitamin C and cataracts and see our Top Picks for vitamin C.)
Vitamin C for Colds? -- (8/3/2018) Taking vitamin C may modestly help with colds, according to a new study -- but there's a catch. Find out in the What It Does section of the Vitamin C Supplements Review. (Also see our Top Picks for vitamin C supplements.)
Exercise Benefit Lost With High-Dose Vitamins -- (4/8/2017) Older men asked to perform resistance (strength) training for 12 weeks showed less gain in bone density if they were given high daily doses of vitamins C & E than if they were given a placebo. This is not the first time that  high-dose antioxidant supplements have been shown to reduce benefits from exercise. For details, see the "Concerns and Cautions" section of the Vitamin C Supplements Review >>
Is Ester-C Better? -- (8/3/2016) One of the forms of vitamin C in supplements is Ester-C. In addition to being non-acidic, a recent study suggests another possible benefit over regular vitamin C (ascorbic acid). Get more information about this and other forms of vitamin C in the "ConsumerTips" section of the Vitamin C Supplements Review >>
Vitamin C and Breast Cancer -- (7/23/2016) Higher intakes of vitamin C from foods are linked to lower risk of postmenopausal breast cancer in women, but getting vitamin C from supplements on top of that may increase the risk, says a new study. Get the details in the Vitamin C Supplements Review >>
Vitamin C: The Exercise Replacement? -- (9/9/2015) A small clinical study recently found that taking vitamin C had a positive effect on blood vessels similar to a daily walk. The study focused on overweight and obese individuals, in whom blood vessel tone is compromised. Long-term effects were not studied. Get details about the study (including dose) and other pros and cons of vitamin C in the Vitamin C Supplements Review >>
When Vitamin C May Curb a Cold -- (8/6/2014) A recent small study among men with low to adequate levels of vitamin C showed that supplementing with vitamin C reduced the incidence of colds compared to placebo. The men taking vitamin C also reported having more energy -- although this finding was not statistically significant. Learn more about what vitamin C can and cannot do, the dose used in this study, and results of our tests of vitamin C supplements, in the update to the Vitamin C Supplements Review >>
Vitamins C & E Blunt Exercise Effect -- (2/7/2014) A recent study found that giving high-dose vitamin C or vitamin E to people involved in intensive exercise training blunted cellular changes thought to be important for improving muscular endurance. These and similar results recently reported with resveratrol raise concerns about high-dose antioxidant supplementation during exercise training. For details, see the updates to the "Concerns and Cautions" sections of the Vitamin C Supplements Review >>  and the Vitamin E Supplements Review >> 
Antioxidants: Too Much of a Good Thing? -- (8/25/2013)
A new, long-term study of Americans found the risk of dying over the course of the study (about 14 years) was lowest when antioxidant levels in the blood were above the lowest levels (the bottom 20% of the population). However, for people in the top 20% of blood levels for vitamins A and E, the risk of death increased compared to people with moderate levels. For selenium and beta-carotene, there was no significant difference in the death rate between moderate and high levels, although for vitamin C some additional benefit was seen at high, but not the highest, levels.
The results suggest that antioxidant supplements may be useful for those who are nutritionally deficient, but, as noted by the researchers, "beyond a certain threshold, higher levels do not lead to additional benefit, and may potentially be toxic." More details (including specific serum levels) are found in the linked updates to the following reviews, which include our test results and quality ratings of products:
Vitamin C: Does It Fight Colds? -- (6/9/2013) A new analysis says it can help — a little. Get the bottom line, plus test results for 27 products, in the updated Vitamin C Supplements Review >>
Vitamin C and Blood Pressure -- (4/30/2012) Vitamin C supplements may modestly reduce blood pressure, particularly among people with elevated blood pressure, according to a review of the latest clinical studies. Get the details, as well as our tests of vitamin C supplements, in the updated Vitamin C Supplements ReviewMore >>




Product Reviews

In addition to our product reviews our encyclopedia covers the following:

Herbs & Supplements


Drug Interactions

Alternative Therapies


Follow us on...
facebook twitter
Join |  Sign In
Join Us on Facebook! Join Us on Instagram! Join Us on Twitter! Join Us on YouTube! Join Us on YouTube!
Product Tests
Brands Tested
Health Conditions
CL Answers
Clinical Updates
Recalls & Warnings
Where to Buy Products
Raw Materials Tests
Testing Program
How Products Were Tested
Join CL Today
Join Free Newsletter
Group Subscriptions
Gift Membership
About Us
The CL Seal
CL Survey
Privacy Policy
Contact Us/Help

©2019, LLC. All rights reserved. A single copy of a report may be printed for personal use by the subscriber. It is otherwise unlawful to print, download, store or distribute content from this site without permission. name and flask logo are both registered trademarks of, LLC. This site is intended for informational purposes only and not to provide medical advice.