Security Now #1058: "A Gift for the New Year"

Hosts: Steve Gibson, Leo Laporte
Date: December 30, 2025

Episode Overview

This special New Year's Eve edition of Security Now departs from the usual cybersecurity fare to revisit and update a landmark episode from 2009. Steve Gibson revisits his deep research into vitamin D, the science behind it, its impact on health, and new findings he's learned since the original show. The episode covers why supplementation may be necessary, how our environment and aging affect vitamin D, and practical guidance for listeners. The discussion is candid, scientific, and caring—a true "gift for the new year" oriented toward personal health and longevity.

Key Discussion Points & Insights

1. Why Revisit Vitamin D? (00:47–01:35, 12:49–15:01)

• Steve & Leo acknowledge the lack of tech news during the holidays and decide to repeat a personal health-focused episode from 2009, now with updates.
• Steve: “Something has really come onto my radar that I almost feel I have an obligation just to share once…our listeners are important to me.” (12:54)

2. Vitamin D Basics: Production, Deficiency, Misconceptions (02:27–08:54, 21:38–26:00)

• Discusses why natural diet alone may not be enough due to food processing and drastically changed lifestyles.
• The body synthesizes vitamin D via UVB from sunlight—not from most foods.
• Vitamin D is not truly a vitamin, but a steroid hormone, essential for calcium metabolism and many other functions.
• Quote (Steve): “It is the most powerful steroid hormone in the human body...almost no dietary sources...we cannot get D from our diet.” (23:13)
• Historical context: rickets due to deficiency, cod liver oil as an early supplement.

3. The Science & Evolutionary Biology of Vitamin D (26:00–34:05)

• Human evolution: skin pigmentation adapted for sun exposure and vitamin D synthesis.
• Modern life indoors behind glass or with sunscreen reduces sun-driven D production.
• Vitamin D production in skin decreases with age—by age 65, only about 25% of youthful capacity remains.

4. Emerging Research & Epidemiological Data (34:05–47:24)

• Explores studies linking adequate vitamin D to dramatically lowered rates of colon cancer, digestive cancers, and total cancer mortality (by as much as 45% in some studies).
• Quote (Steve): “Individuals whose 25 hydroxy vitamin D levels were greater than 20 nanograms per milliliter had 1/3 the risk of colon cancer.” (34:05)
• Vitamin D’s role in mood (e.g., seasonal affective disorder), immunity (flu outbreaks in hospitals), and theories around latitude, vitamin D, and autism.

5. The Modern "Deficiency Crisis" (47:24–54:39)

• Reasons for widespread deficiency include less sun exposure, indoor living, and aging.
• Government-mandated fortification (milk) is not enough—most people would need to drink impractical amounts for sufficiency.
• "We have an unrecognized epidemic among both children and adults in the United States." (34:05)
• Recommendations for supplement use have changed; routine blood testing for D is now common.

6. How Much Vitamin D Do You Need? Testing & Supplementation (54:39–76:41)

• Old RDA (400 IU) based on rickets prevention is outdated; half an hour sunlight can make 10,000 IU.
• Supplementation is safe within reason; Steve describes self-testing and suggests aiming for lab values between 50–70 ng/ml.
• Quote: “Taking vitamin D infrequently like that [one 5,000 IU pill every three days] works because it has on the order of about a three or four week half life in our body.” (67:38)
• Cheap, effective supplements: recommends D3 (cholecalciferol) over D2.

7. Caveats and Medical Advice (09:42–10:22, 74:03–80:11)

• Not medical advice! Listeners should check with their physicians, especially if on medications like blood thinners.
• Possible toxicity with very high, excessive supplementation; responsible dosing and periodic blood testing is best.
• Quote (Steve): “We're not doctors. Consult your physician…But my point is that you can take a large dose and then let it be acquired by your system and then used over time as your blood level drops.” (76:41)

8. Dietary Sources & Other Supplement Notes (80:11–81:24)

• Food sources (salmon, oily fish) provide only limited D; cod liver oil also contains vitamin A, which in excess may counteract D’s benefits.
• Vegans/vegetarians: D2 from plant sources less effective; D3 typically from animal sources, but research ongoing.

Notable Quotes & Memorable Moments

• On why this matters:
  “I'm literally willing to do anything it takes every single day so that I'm able to jump around more or less as I am now as I continue aging…you want to maximize the area under that [health] curve.” —Steve Gibson (15:08)

• On vitamin D as a hormone, not a vitamin:
  “It is such a shame that it's been lumped in with the vitamins because it is a steroid hormone. Really.” —Steve Gibson (23:13)

• On evidence from research:
  “An increment of 25 nanomoles per liter in predicted vitamin D level was associated with a 17% reduction in total cancer incidence…a 45% reduction in digestive system cancer mortality.” —Steve Gibson (34:05)

• On testing and personal experience:
  “My first test showed me at 23.6 nanograms per milliliter…after a week of sun, completely exposed…dropped to 21.3…I’m unable to produce vitamin D through being out in the sun.” —Steve Gibson (54:39)

• On realistic supplementation:
  "My favorite supplier is a company called Now Foods...120 [5,000 IU] pills costs $8.80. If you take one every three days, that's a year's supply for $8.80.” —Steve Gibson (67:38)

• On practical advice:
  “The really responsible thing to do is to get a test…as long as you follow the label, you cannot be toxic.” —Steve Gibson (75:35)

Updated Recommendations & Practical Takeaways

• Blood Testing: Vitamin D status is now a routine blood test; ask your doctor.
• Supplementation: Steve now strongly recommends vitamin D3 plus K2 for most adults, especially those not frequently in the sun.
• K2 Addition: New research suggests K2 helps direct calcium appropriately when supplementing D.
  • “K2 carboxylates two proteins, which have the effect of driving the calcium into your bones, which is where you want it to go and keeping it out of your arteries.” (06:07)
• Risks: For those on prescription blood thinners (like warfarin), consult a physician before starting K2 (09:53).
• Target Levels: Aim for 50-70 ng/ml blood levels (as per Steve’s reading).
• Forms: Prefer D3 (cholecalciferol) over D2 (ergocalciferol).
• Annual Reassessment: Regular vitamin D testing recommended to tailor supplementation.

Timestamps for Notable Segments

• How Steve got interested & history of prior episode: 01:12–02:27
• Sunlight, diet, and D production basics: 02:43–04:00
• K2 update & calcium handling: 04:42–06:09
• Anecdotes on D & immune health (including COVID/flu): 06:56–08:26, 07:37
• Vitamin D isn't really a vitamin: 21:38–23:13
• Cancer studies, risk reduction stats: 34:05–34:07
• Deficiency epidemic & why food fortification fails: 47:24–54:39, 74:03–75:14
• How/why sun exposure often isn’t enough: 59:39–67:38
• Supplements: brands, dosing, forms: 67:38–75:12
• Practical advice/testing your levels: 75:35–76:41
• Dietary sources & more Q&A: 80:11–81:27
• Final thoughts / GRC.com vitamin D page: 84:09–84:40

Tone & Style

The episode is research-driven but highly conversational, with Steve sharing deep-dive science in a clear, methodical way. Leo provides lively, relatable commentary and prompts practical takeaways. The hosts repeatedly stress this is not medical advice, and listeners should consult their doctors.

Where to Learn More

• Steve’s Updated Vitamin D Page: GRC.com → Research → Health → Vitamin D
  • Includes references, dosing, supplement recommendations, and medical literature.
• Get Tested: Ask your doctor for a 25-hydroxy vitamin D blood test.

Summary

• Vitamin D is vital to immune function, cancer resistance, mood, and more; modern lifestyles and aging reduce natural levels.
• Supplementing with vitamin D3 (with K2) is safe, inexpensive, and powerful, but dosage should be guided by regular testing.
• “If I had to choose one single supplement… I think it would be vitamin D because of its powerful immune support.” —Steve Gibson (85:08)

For the full research and recommendations, see Steve’s page at GRC.com. Happy New Year and good health from Security Now!