Podcast Summary: ZOE Science & Nutrition

Episode: Top Doctor: The Hidden Dangers in Your Daily Multivitamin
Host: Jonathan Wolf (ZOE)
Guest: Dr. David Seres, Director of Medical Nutrition and Professor at Columbia University
Release Date: September 4, 2025

Episode Overview

This episode dives deep into the truth about vitamin and supplement use, exposing the gaps in regulation, the marketing myths, and the real science—or lack thereof—behind daily multivitamins. Dr. David Seres, a physician expert in nutrition for critically ill patients, guides listeners through the surprising legal history, scientific evidence, and practical advice for those considering supplements. Throughout, the conversation maintains an engaging, myth-busting tone, empowering listeners to critically evaluate their supplement choices.

Key Discussion Points & Insights

1. The Origins & Regulatory History of Vitamins

• Initial Breakthroughs:
  Vitamins once offered miraculous cures for severe deficiencies (scurvy, rickets, goiter).

  • [03:02] Dr. Seres:
    “The whole nickname of British sailors as limeys was because they ate limes...because it cured scurvy, because there's vitamin C in limes...”

• From Medicine to Massive Industry:
  America’s supplement industry skyrocketed after the 1994 Dietary Supplement Health and Education Act (DSHEA), which removed nearly all federal oversight.

  • [05:54] Dr. Seres:
    “There was a bipartisan effort...this law...essentially deregulates anything brought to the market that's called a dietary supplement...left specific ways in which the supplements were allowed to advertise suggestively.”

• Hollywood’s Role – Mel Gibson’s Ad:
  A viral ad campaign with Mel Gibson, dramatizing a raid for possessing vitamins, triggered public outcry and Congressional action.

  • [06:20] Dr. Seres:
    “That advertising campaign got more letters written to Congress than the entire Vietnam War.”

• Consequences:
  Supplements can make structure/function claims (“supports heart health”) without proof, with no requirement for pre-market approval, and minimal regulation compared to pharmaceuticals.

  • [08:21] Dr. Seres:
    “A drug company has to undergo a series of randomized control trials...Dietary supplements are treated as if they were a completely different thing...so they're available without any science necessary...without any safety testing.”

2. Public Perception, Marketing, and Misleading Claims

• General Misconceptions:
  Most Americans are unaware just how unregulated supplements are.

  • [09:59] Dr. Seres: “I don't think so, no.”

• Marketing Outpaces Science:
  Companies use suggestive, science-sounding claims that skirt direct disease treatment language.

  • [11:08] Dr. Seres: “I could...put...crushed up rose hips and tell you that it supports your kidney health and make a lot of money. There's really nothing that precludes that.”

• Scientific Spin:
  Supplement manufacturers frequently cite weak evidence, cherry-pick studies, or even use experimental cell data irrelevant to real-world health.

  • [16:19] Dr. Seres:
    “...if you do A and get B and do B and get C and do C and get D, the likelihood of doing A and getting D is close to zero because of all the intervening processes...it's never a straight line in biology.”

  • Example: Prostate Cancer Study
    Supplement levels in the body were assumed to be a cause, but large RCTs found that vitamin E and selenium supplementation increased, rather than decreased, cancer risk.

    • [18:29] Dr. Seres:
      “...anyone who received either vitamin E or selenium had about 18% increased rate of prostate cancer.”

3. Understanding the Science—And Its Distortion

• Levels of Evidence:
  Observational studies ≠ cause/effect; randomized controlled trials (RCTs) are the gold standard.

  • [23:27] Dr. Seres:
    “What we really want is a study that gives us information that's actionable, gives us information that talks to us about cause and effect.”

• Manipulation of Data:
  Inflated claims sometimes result from cherry-picking positive results among many negative ones in subgroup analyses.

  • [21:09] Dr. Seres (memory pill litigation):
    “If you take a large enough data set and analyze it enough times, you'll find something...statistically significant but not relevant...they thought they could then claim that they had good evidence that they improved memory...it was a biological impossibility.”

4. The Role (and Failings) of the Scientific Community

• Scientists’ Shifting Guidelines:
  Mistakes—like the push for low-fat diets—have eroded public trust. Scientists sometimes overstate evidence and fail to communicate its nuance.

  • [31:35] Dr. Seres:
    “It was bad advice. In fact, low-fat diet may in some people at least...predisposed to weight gain...carbohydrates have an effect on appetite hormones...”

• Openness to Change:
  Good science means admitting when previous recommendations were wrong.

  • [32:07] Jonathan Wolf:
    “You recognize a good scientist because they say, oh, I've changed my mind on things.”

5. What The Evidence Really Shows About Specific Supplements

Vitamins in the General, Healthy Population

• Dr. Seres’s Rule:
  For most, focus on balanced, less-processed foods.
  Only supplement under physician advice for clear deficiencies.

  • [33:06] Dr. Seres:
    “...unless you have an identified risk or deficiency that your doctor has recommended...there is really no benefit to any of these with a couple of minor exceptions.”

Vitamin C

• No benefit for healthy people; possible minor benefit in endurance athletes (lower cold incidence), at lower doses.
  • [35:15] Dr. Seres: “...really no salutary benefit...with one minor exception...intense skiers and marathon runners had fewer colds if they took vitamin C...”

Vitamin D

• “Insufficient” lab ranges were arbitrarily set; mass supplementation is unsupported for most.
• Slight, questionable benefit in elderly (potentially fewer falls).
• Mega-doses are actively harmful (risk of toxicity, calcium deposits).
  • [36:29] Dr. Seres: “Vitamin D is a real headache...randomized controlled trials...have not shown to have much benefit.”
  • [37:19] Dr. Seres: "Vitamin D at high doses can be very toxic. There are real, potentially even deadly consequences.”

Critically Ill & Elderly

• No clear benefit even in ICU patients. Observational associations often due to illness, not deficiency.
  • [43:12] Dr. Seres:
    “...even in that extreme a situation...there's no benefit.”
• Routine multivitamin for elderly? No convincing evidence, potential for harm.
  • [43:44] Dr. Seres: “...still very weak...I really just can't get behind the idea of wholesale supplementation simply because you’re over a certain age.”

Probiotics and Prebiotics

• Most do not contain microbes that colonize the human gut.
• Little evidence of benefit, except in some specific, minor circumstances.
  • [46:35] Dr. Seres:
    “...most of the probiotics are not normal inhabitants of the intestine...they don’t survive much past the stomach...to expect a salutary benefit...seems to me far-fetched.”

6. Dietary Advice & What You Should Actually Do

• Eat food that resembles its form when it was harvested or alive (“less processed, more fresh”).

• Emphasize a diversity of plants and fiber, but admit evidence is suggestive—not definitive—except for clear deficiency or at-risk groups.

  • [51:05] Dr. Seres:
    “a diet that’s got a lot of things that look more like what it looked like when it was harvested...avoid the heavily processed foods...shift away from meat and animal products..."

• Strongest advice: don't waste your money on supplements unless medically indicated, and beware the potential for harm in the absence of benefit.

  • [53:54] Dr. Seres:
    “It would be look at your diet and don’t go to the vitamin store.”
    • (Final advice—memorable closer)

Notable Quotes & Memorable Moments

• On the biggest myth of vitamin supplements:
  [02:24] Dr. Seres:
  “The biggest myth about vitamin supplements is that if some is good, more must be better and will have health benefit and will be safe...It’s not true.”

• On how little regulation exists:
  [11:34] Dr. Seres:
  "I could...sell crushed up rose hips and tell you that it supports your kidney health and make a lot of money. There's really nothing that precludes that."

• On biological complexity:
  [16:19] Dr. Seres:
  "It’s never a straight line in biology."

• On changing advice:
  [31:37] Dr. Seres:
  “It was bad advice. In fact, low-fat diet may in some people...predisposed to weight gain.”

• Final actionable tip:
  [53:54] Dr. Seres:
  “It would be look at your diet and don’t go to the vitamin store.”

Key Segment Timestamps

• [00:57]–[02:35]: Quickfire Myth-busting on Vitamins
• [05:54]–[07:35]: The 1994 DSHEA Law and Mel Gibson ad
• [16:19]–[20:04]: How biology complicates claims and why correlation isn’t causation
• [21:09]–[23:27]: How supplement advertisers twist science and why RCTs matter
• [33:06]–[34:23]: Dr. Seres’s core advice on supplements
• [35:15]–[37:19]: Deep dives into vitamin C and D science/effectiveness & risks
• [39:10]–[43:12]: Vitamins in critical illness—case studies and COVID-19 evidence
• [49:27]–[53:38]: Dietary patterns, limitations of nutrition science, and fiber/plant diversity

TL;DR—Dr. Seres’ Core Recommendations

• Do NOT take vitamin or other dietary supplements unless you have an established deficiency or a doctor’s advice.
• Supplements are largely unregulated, can make misleading claims, and rarely have supporting RCT evidence.
• Focus on a balanced, minimally processed diet rich in plant diversity and fiber.
• Mega-dosing on vitamins like D can be actively dangerous.
• Science is complex and evolving: be wary of new claims, and be open to changing your mind as new evidence arises.
• If you’re healthy and have no deficiencies, save your money—the best investment in your health is in your plate, not your pills.

Memorable closer:
[53:54] Dr. Seres:
“It would be look at your diet and don’t go to the vitamin store.”