Two Nobel prizes didn’t settle vitamin C, a lesson in judging an expert

Key takeaways

• Linus Pauling won two unshared Nobel Prizes, yet two Mayo Clinic trials of high-dose vitamin C pills found no benefit for people with advanced cancer.
• DocInfo.org, run by the Federation of State Medical Boards, covered more than one million physicians and physician assistants as of 2025 and lets you check licenses and disciplinary actions for free.
• ABMS Certification Matters shows, at no cost, whether a doctor holds board certification from one of 24 member boards, or whether it lapsed or was revoked.
• In a 2012 study of 2,047 retracted biomedical papers, about two in three were pulled for misconduct; the Retraction Watch database, free to search since 2023, held more than 64,000 retractions by April 2026.
• A license is a floor, not proof: in a 2023 study, 50 of 52 U.S. doctors who posted COVID-19 claims that conflicted with CDC guidance held licenses.

Linus Pauling is the only person ever to win two Nobel Prizes on his own¹. He took the chemistry prize in 1954 and the peace prize in 1962¹. Few scientists of the 20th century carried more authority.

In 1970, Pauling published a bestseller, Vitamin C and the Common Cold¹. Millions of people changed their diets, and vitamin C sales soared¹. In the 1970s, he also teamed up with Scottish surgeon Ewan Cameron to study vitamin C for cancer².

Their 1976 report compared 100 people with terminal cancer who got high doses of vitamin C with 1,000 matched patients from the same hospital’s past records²⁴. The authors claimed the vitamin group lived about 300 days longer on average². There was no placebo group, which gets a dummy treatment so the comparison is fair⁴.

Researchers at the Mayo Clinic then ran two randomized trials, where chance decides who gets the real treatment²³⁴. Patients took either a placebo or 10 grams of vitamin C a day by mouth. On survival, symptoms and the ability to carry on daily life, the two groups came out the same in both trials².

Pauling was a brilliant chemist. That didn’t make him right about cancer care. The useful question was never “Is this person an expert?” It was “Is this person an expert on this claim, and has the claim been tested?”

This guide gives you five free checks to answer that question for any doctor, scientist or wellness expert.

Check 1: Does the expert’s training fit the claim?

Credentials are real information. A license, a residency and board certification mean someone passed demanding tests in a field. Our guide to the letters after a practitioner’s name explains what each degree means.

But expertise has borders. Pauling trained in chemistry, earning his Ph.D. at Caltech and later leading its chemistry division¹. Cancer treatment is a different field, with its own methods for proving that a therapy helps patients.

That gap matters more than ever online. A cardiologist may weigh in on nutrition, a surgeon on vaccines, a chiropractor on hormones. Each may be right, but the credential doesn’t settle it.

Start by stating the claim in one sentence. “This herb lowers blood pressure.” “This diet reverses diabetes.” Then ask which field studies that question, and look for these matches:

• Degree and field. A Ph.D. in physics is a real doctorate, but it isn’t medical training. A medical degree isn’t training in nutrition research.
• Specialty. An endocrinologist talking about thyroid disease is in her lane. The same doctor on cancer treatment is a well-read outsider.
• Hands-on work. Has the person treated patients with this problem or run studies on it?

An outsider can still be right. But when someone speaks outside their training, the claim should lean harder on outside evidence and less on the speaker’s title.

Check 2: Verify the license, the minimum bar

A license means a state allows someone to practice. It’s a floor, not a ceiling. Our article on state licensing explains what boards do and don’t promise.

For physicians and physician assistants, start at DocInfo.org. The Federation of State Medical Boards runs it, and it’s free⁵⁶.

The Federation of State Boards of Physical Therapy profiled the tool in 2025. DocInfo holds background on over a million licensed doctors and physician assistants⁶. For each one, you can see active licenses by state, medical school, specialty and any board discipline, with records reaching back to the early 1960s⁶. The site handled close to 3 million doctor searches in 2024 alone⁶.

DocInfo has limits. When a reporter tested it in 2015 with 20 doctors who had known disciplinary records, it found 18 of them⁷. For the details of a case, you often have to visit the state board’s own site and search again⁷.

Other professions are patchier. Physical therapists have no national lookup yet, and each state runs its own, with search pages that vary in quality⁶. For nurses, chiropractors, acupuncturists or naturopathic doctors, search for your state’s licensing board for that profession. Make sure the lookup belongs to the official board, not a directory that sells listings.

A license doesn’t guarantee accurate advice

Credentials can’t do the whole job, and a 2023 study shows why. Researchers at the University of Massachusetts Amherst tracked U.S. physicians who posted COVID-19 claims on major social platforms from January 2021 through December 2022¹³¹⁵. They judged the claims against CDC guidance on preventing and treating the disease¹³.

They found 52 such physicians. Fifty held licenses, and they came from 28 specialties¹³.

On Twitter alone, 37 of them had 9.1 million followers combined¹³. Claims about vaccines were the most common, and about three in four doctors spread claims in more than one category¹³¹⁵. Nearly a third belonged to groups with long records of spreading medical misinformation¹⁴.

Few faced discipline. The authors noted that licensing boards lack the resources to monitor social media¹³.

The lesson cuts every way. A license tells you a board approved someone to practice. It doesn’t check their posts, their podcast or their book. That’s true of the TV doctor, the celebrity surgeon and the naturopath with a big following.

Check 3: Confirm board certification, and which board

Board certification shows that a doctor completed training in a specialty and passed its exams. For the 24 member boards of the American Board of Medical Specialties (ABMS), that means a medical degree, three to five years of residency, a full license and passing the board’s exams⁸.

ABMS runs a free lookup called Certification Matters, listing over a million doctors certified by its member boards⁹. A search tells you a doctor’s status, such as certified, no longer certified, suspended or revoked, and whether they are keeping their certification current⁹. DocInfo also shows specialty certification from both ABMS and the American Osteopathic Association⁵.

Watch for gaps. Chiropractors, dentists, oral surgeons and podiatrists aren’t in the database, and a doctor who just passed the boards may be missing for as long as 90 days⁹.

Watch the wording, too. “Board certified” should come with the name of a real board. Some groups hand out certificates after a weekend course or an online quiz. Our guide to telling a real certification from a logo shows how to check.

Check 4: Look for a track record, including retractions

Real expertise usually leaves a trail. Search the person’s name in PubMed, the National Library of Medicine’s free index of medical research. Look for studies on this topic, not just opinion pieces, and notice whether they appeared in peer-reviewed journals.

A thin record isn’t damning. Many excellent clinicians treat patients rather than publish. But someone who calls themselves a leading researcher should have research you can find.

Then check for retractions, which happen when a journal withdraws a paper. In 2023, the scholarly-records organization Crossref acquired the Retraction Watch database and made it free and open¹⁰. Combined with Crossref’s own records, it held about 50,000 retractions at the time¹⁰.

In April 2026, Retraction Watch managing editor Kate Travis testified before a House science subcommittee. Her written statement said the database now held more than 64,000 retractions¹¹. She put the retraction rate at about 0.2% of articles, up from 0.02% in the early 2000s¹¹. Retractions are still rare, in other words, but far less rare than they were.

Why does a retraction matter? In a 2012 study of 2,047 retracted biomedical papers, 67.4% were pulled for misconduct, including fraud or suspected fraud in 43.4%¹². Honest error explained 21.3%¹².

Read the reason before you judge. A scientist who retracts a paper after finding their own mistake is showing integrity. A string of retractions for faked data is a different story.

Check 5: Listen to how they handle uncertainty

Training and records tell you about the person. The way they talk tells you how they think.

Good experts usually:

• Say how sure they are, and why.
• Separate what trials show from what they’ve seen in their own patients.
• Tell you who might be harmed and when to see someone else.
• Name their money ties, such as products, clinics or affiliate links.
• Change their minds when strong new evidence arrives.

Be cautious when someone claims total certainty on an open question, says every other expert is lying, or sells the fix they recommend. Our companion articles on conflicts of interest and on recognizing uncertainty go deeper.

Many people come to natural health after an expert let them down. Asking “How do you know?” is a healthy habit. Apply it evenly: to the hospital specialist, the supplement company’s “medical advisor” and the beloved wellness author alike.

Pauling’s story ends with a narrower, fairer question

It’s tempting to tell Pauling’s story as a simple warning. The full version is more interesting, and it shows how science treats a bold idea.

The Mayo trials used vitamin C pills. Cameron’s patients, by contrast, had started with 10 days of vitamin C given by vein before switching to pills, and neither Mayo trial used the IV route². Research by NIH scientists later showed that the body tightly limits how much vitamin C from pills reaches the blood²⁴. An intravenous drip, given straight into a vein, can push blood levels far higher, more than 25 times higher for the same dose in one analysis⁴.

That finding reopened a narrower question. Some researchers support testing high-dose IV vitamin C again, and trials are under way²³. As of the National Cancer Institute’s 2024 summary, the FDA has not approved it to treat cancer².

It can harm people with kidney problems or an inherited enzyme shortage called G6PD deficiency². If you’re considering it, talk with your cancer care team first.

Colds got a similar narrowing. A Cochrane review summarized by NIH found that regular vitamin C doesn’t prevent colds in most people³. It did shorten them, by 8% in adults and 14% in children, and it cut colds in half among marathon runners, skiers and soldiers under extreme strain³.

Pauling raised a real question and overstated the answer. Careful testing kept the useful part. That’s what checking the claim, and not just the person, accomplishes.

Your five-step expert scorecard

Use this table the next time a confident voice tells you what to take, skip or fear.

Step	What to ask	Where to look	Green flag	Red flag
1. Fit	Is their training in the field this claim belongs to?	Bio, degree, specialty	Trained and working in this exact area	Famous for something else
2. License	Can they legally practice?	DocInfo.org; state board lookup	Active license, no serious actions	Lapsed, restricted or revoked
3. Board	Are they certified in the right specialty?	Certification Matters; DocInfo	A named, recognized board; current status	An unnamed “board” or weekend certificate
4. Record	Have they studied or treated this problem?	PubMed; Retraction Watch database	Peer-reviewed work on the topic	Retractions for misconduct; nothing findable
5. Manner	Do they admit limits and disclose ties?	Their posts, talks and sales pages	Sources, caveats, disclosures	Total certainty, claims of persecution, selling the cure

Then ask one more question: has the claim itself been tested? A perfect score on the person never replaces evidence about the claim.

What the evidence shows for the claims in this story

Claim	Evidence level	Basis
High-dose oral vitamin C helps people with advanced cancer live longer	Evidence says no, or unsafe	Two placebo-controlled Mayo Clinic trials found no benefit23
High-dose IV vitamin C treats cancer	Not enough evidence	Not FDA approved; trials are under way2
Regular vitamin C prevents colds in most people	Evidence says no, or unsafe	Cochrane review summarized by NIH3
Regular vitamin C shortens colds a little	Strong evidence for a small effect	Same review: 8% shorter in adults, 14% in children3
A license or title guarantees accurate advice	Evidence says no, or unsafe	Licensed physicians spread claims that conflicted with CDC guidance13

Questions readers ask

The bottom line

Credentials are a starting point. They show that someone trained in something and that a board lets them practice. They can’t show whether a particular claim, in a particular field, has been tested.

Run the five checks: fit, license, board, record and manner. Then ask for the evidence behind the claim itself. Linus Pauling’s story shows that even two Nobel Prizes can’t take the place of a fair trial.

Related reading

• What the letters after a practitioner’s name mean
• How state licensing works, and what it doesn’t promise
• How to tell a real certification from a logo
• Health coaching is real, unregulated, and easy to get wrong
• Simple health answers feel true, so how do you tell which ones are?

Sources

1. Hager T. “Linus Pauling (1901–1994).” The Oregon Encyclopedia, Oregon Historical Society. oregonencyclopedia.org
2. National Cancer Institute. “Intravenous High-Dose Vitamin C (PDQ)–Health Professional Version.” NCI, updated April 5, 2024 (NCBI Bookshelf).
3. NIH Office of Dietary Supplements. “Vitamin C: Fact Sheet for Health Professionals.” National Institutes of Health, updated July 31, 2025. ods.od.nih.gov
4. Cantley L, Yun J. “Intravenous High-Dose Vitamin C in Cancer Therapy.” Frederick National Laboratory for Cancer Research, RAS Dialogue, January 24, 2020. frederick.cancer.gov
5. Federation of State Medical Boards. “DocInfo Tool Provides Consumers Physician Licensure, Disciplinary Data.” News release via Newswise, August 19, 2015. newswise.com
6. Federation of State Boards of Physical Therapy. “Building a Public Licensure Lookup for Physical Therapy.” FSBPT Forum, 2025. fsbpt.org
7. Center for Health Journalism, USC Annenberg. “License Overdrive: Updated Website Makes Tracking Doctors’ Missteps Easier.” September 9, 2015. centerforhealthjournalism.org
8. American Board of Medical Specialties. “Verify Certification.” ABMS. abms.org
9. American Board of Medical Specialties. “ABMS Certification Matters: FAQs.” ABMS. certificationmatters.org
10. Crossref. “News: Crossref and Retraction Watch.” Crossref blog, September 12, 2023 (updated 2024). crossref.org
11. Travis K (Managing Editor, Retraction Watch). Written testimony for the hearing “The State of Scientific Publishing: Assessing Trends, Emerging Issues, and Policy Considerations,” Subcommittee on Investigations and Oversight, U.S. House Committee on Science, Space, and Technology, April 15, 2026. republicans-science.house.gov
12. Fang FC, Steen RG, Casadevall A. “Misconduct Accounts for the Majority of Retracted Scientific Publications.” Proceedings of the National Academy of Sciences, 2012 (summary via Online Ethics Center). pubmed.ncbi.nlm.nih.gov
13. Bendix J. “New Study Sheds Light on Doctors’ Use of Social Media to Spread COVID-19 Misinformation” (on Sule S, et al., JAMA Network Open, 2023). Medical Economics, August 17, 2023. medicaleconomics.com
14. Australian Science Media Centre. “These 52 US Doctors Spread a Heap of COVID-19 Misinformation” (JAMA Network Open press summary). Scimex, August 2023. scimex.org
15. Heath S. “How Common Is Medical Misinformation Spread by Physicians?” TechTarget Patient Engagement, August 16, 2023. techtarget.com