Security Now 1058: "A Gift for the New Year - Vitamin D Revisited"

Date: December 28, 2025
Hosts: Steve Gibson & Leo Laporte

Episode Overview

For this special New Year's Eve edition, Steve Gibson and Leo Laporte set aside their typical deep-dive into cybersecurity to revisit an earlier "personal security" episode about vitamin D. Steve updates listeners on the science behind vitamin D, its crucial role in health, and what he's learned—and changed—since the original show in 2009. The discussion is detailed, covering biology, evolution, public health, supplementation strategy, and even Steve’s own experiments.

Key Discussion Points & Insights

The Motivation Behind the Episode

• Lack of Security News: The year’s end left few new cybersecurity stories, making it ripe for a special topic ([00:47]).
• A Unique Approach: Steve recalls when he first tackled vitamin D on Security Now in 2009, focusing on “personal security” for health—a rare departure from tech topics, but one he felt passionate to share ([01:12], [12:49]).

Why Vitamin D? Steve’s Personal Journey

• Midlife Health Curiosity: After finishing SpinRite 5, Steve found himself with time and curiosity about his long-term health ([01:35]).
• Analytical Approach: Inspired by seeing aging travelers at airports and deciding “not to be that person,” Steve dove into health optimization via research ([15:08]).
• Quality Over Longevity: Steve wants to maximize quality of life, not just length:
  "You want to maximize the area under that curve. That's the most health you can have for the time you're alive." ([15:08])

The Science: What Is Vitamin D, Really?

Not Just a Vitamin—A Hormone

• Vitamin D is actually a steroid hormone—the strongest in the human body—not a “vitamin” by the classic dietary definition ([21:41], [23:13]).
• It’s produced endogenously in the skin via UVB sunlight interacting with cholesterol, and is not found in significant dietary sources ([22:03], [23:13]).
• Blood levels are usually measured as 25-hydroxy vitamin D ([23:09]).

The Biochemical Pathway

• 7-dehydrocholesterol (in the skin) → exposure to UVB → converts to cholecalciferol (D3) → processed in liver and kidney into active hormone ([25:11]).
• This process is inefficient or impaired with age, darker skin, or limited sun exposure ([67:38], [68:12]).

Evolution, Skin Color, and Sunlight

• Evolution in Africa: Early humans developed dark skin (rich in melanin) to survive equatorial sun exposure while maintaining critical vitamin D production ([27:27]).
• Migration and Depigmentation: As humans moved northward, skin lightened via natural selection to allow sufficient D production under weaker sun ([43:39]).
• Modern life—indoor living, glass, sunscreen—has greatly reduced synthesis ([02:43], [43:39]).

Health Implications & Modern Deficiency

Disease Links (Supported by Correlation, Not Causation)

• Deficiency Dangers: Linked to rickets, osteoporosis, various cancers, cardiovascular disease, multiple sclerosis, rheumatoid arthritis, type 1 diabetes, allergies, autism, and more ([34:05], [53:32], [66:53]).

• Immune Support: Vitamin D is shown to bolster immune function; during COVID-19, higher D status correlated with better outcomes ([07:37], [08:20], [42:06]).

  • "It’s a very strong immune support vitamin, which actually is not a vitamin… it’s actually a hormone." —Steve ([08:10])

• Psychological Impact: Low D has been tied to mood disorders and Seasonal Affective Disorder ([40:14]).

Deficiency Is Epidemic

• Many Americans—children and adults—have low levels; rickets is returning as milk consumption drops ([53:32], [74:38]).
• Blood pressure and D: There’s a known seasonal rhythm to blood pressure that matches sun exposure ([54:03]).

Testing, Supplementation, and Practical Advice

Blood Levels

• Terms used: Deficient, Insufficient, Sufficient, Toxic ([54:58]).
• Ideal target: Steve advocates for blood levels between 50–70 ng/mL; the accepted “normal” is 32–100 ng/mL ([54:58]).
• Sunshine Alone May Not Be Enough: Age and skin tanning reduce endogenous D synthesis, even with deliberate sun exposure ([67:38], [68:12]).

Supplementation

• Forms: D2 (“ergocalciferol”, plant-based, less effective) vs. D3 (“cholecalciferol”, matches body’s own production) ([77:54]).
• Dosage Safety:
  • Up to 2,000 IU/day is broadly considered safe (U.S. government); some studies show much higher doses are still safe ([78:43]).
  • Toxicity is only at much higher, prolonged doses. “As long as you follow the label, you cannot be toxic.” —Steve ([76:48]).
• Steve’s Method: Gets blood tests (using LabCorp, ordered via Life Extension Foundation). Monitors results as he adjusts dosage ([75:51]).
• Recommended Product Example: “Now Foods” 5,000 IU D3 (one cap every three days; D is fat-soluble and persists in the body) ([70:43], [71:39]).
  • Year’s supply can cost under $9 ([71:39]).

The Kicker: Add Vitamin K2!

• Updated Advice (2025): Newer research supports pairing D3 with K2 to direct calcium safely to bones and away from arteries and kidneys ([04:43], [05:11]).
  • "Raising your blood level of D also causes calcium and phosphorus to be more strongly absorbed...adding some K2 drives the calcium into your bones and keeps it out of your arteries." —Steve ([05:11])

Important Caveats

• Check With Your Doctor: Especially if on blood thinners, or if you have conditions that impact D metabolism ([09:42]).
  • K vitamins are “blood clotters,” the opposite of blood thinners like warfarin ([09:53], [10:02]).

Notable Quotes & Memorable Moments

• "It's not the healthy daily requirement, which is one of the things that has steered so many people wrong." —Steve ([04:18])
• "Nobody makes any money on it." —Leo, on the lack of vitamin D studies ([06:53])
• "I want to maximize the area under that curve… the most health you can have for the length of time that you’re alive." —Steve ([15:08])
• "It is so powerful that… the active form… is measured in picograms per milliliter… 20 to 50 trillionths of a gram in our blood." —Steve ([23:13])
• "So my point is that… as I get older and what happens is we lose the cholesterol in our skin… no amount of sun can give it to you… the only solution is to monitor your vitamin D levels and supplement." —Steve ([68:12])
• "If I had to take one thing, if I, if I were… on a desert island… I would take vitamin D." —Steve ([72:43])
• "There are studies that demonstrate that cancer, autism, allergies, diabetes… have latitudinal correlations." ([66:53])
• "Being in the sun releases… a form of narcotic… we were meant to be in the sun. We evolved in the sun." ([66:12])
• "Check with your physician. This is not an ad. We don't have an advertiser selling vitamin D—this is a man who is brilliant, an autodidact who loves researching deeply into a variety of fields." —Leo ([10:42])

Timestamps for Important Segments

| Topic/Segment | Timestamp | | ------------------------------------------------------------- | -------------------- | | Introduction, intention for special episode | 00:47 – 01:35 | | Steve’s background, why focus on health/vitamin D | 01:35 – 02:27 | | Explanation: Vitamin D synthesis, sunlight, and diet | 02:43 – 04:28 | | Importance of pairing D3 with K2 | 04:43 – 06:07 | | Anecdotal health effects, immune support | 06:53 – 08:26 | | Bio/chemistry: What is Vitamin D? | 21:38 – 23:13 | | Evolution and skin color | 27:27 – 30:12 | | Cancer and disease correlations | 34:05 – 40:14 | | Accounts of institutional supplementation (flu case study) | 40:14 – 41:58 | | Modern epidemic of deficiency | 53:32 – 54:58 | | Steve’s experiment measuring his own D levels | 54:58 – 59:39 | | Sun exposure, limitations with aging | 67:38 – 68:12 | | Supplementing: How, what kind, how much? | 70:43 – 72:43 | | Food sources (lack thereof), only oily fish matter | 80:11 – 81:27 | | Concluding thoughts: Summary, web link for more info | 84:09 – 84:23 |

Recommendations & Takeaways

• Get Your Levels Checked: Ask your doctor for a vitamin D test, particularly at your next physical.
• Supplement with D3, Not D2: D3 (cholecalciferol) matches what your body makes naturally; D2 (ergocalciferol) is less effective.
• Consider D3 Plus K2: Newer evidence suggests the pairing helps direct calcium correctly.
• Don’t Rely on Sun Alone: Aging and tanning reduce your D production; supplementation is safest, especially for older adults or those living at high latitudes.
• No Foods Are Enough: Outside of fatty fish, little is available via diet; milk isn’t sufficient for adult needs.
• Monitor for Safety: Over-supplementation is rare but possible; best practice is to keep levels monitored by blood tests.
• Consult with a Professional: Always check with your doctor, especially if you have health conditions or take medications that might interact.

Final Notes

• More Information: Steve’s vitamin D research, including references, is available at grc.com > Health.
• Not Medical Advice: Steve and Leo emphasize—they are not doctors; listeners should seek personal medical guidance.

This episode stands out as a rare but important health-focused installment of Security Now, echoing the spirit of public service and deep research that Steve brings to all his work—whether digital or biological security.