Vitamin D Is Crucial!
Vitamin D is found naturally in only a few foods, with the richest sources being fatty fish such as salmon, mackerel, sardines, tuna, and trout, along with cod liver oil.
Smaller amounts occur in egg yolks, beef liver, and cheese, while many people also get vitamin D from fortified foods including milk, plant-based milks (soy, almond, oat), yogurt, breakfast cereals, and orange juice
Additionally, UV-exposed mushrooms (such as certain portobello or maitake mushrooms) can provide meaningful amounts of vitamin D, making them a notable non-animal source.
People may have low vitamin D for many reasons, including limited sun exposure from indoor lifestyles, sunscreen use, covering clothing, winter months, or living at northern latitudes; darker skin, which reduces vitamin D synthesis; aging, as skin becomes less efficient at making vitamin D; low dietary intake, since few foods naturally contain it; malabsorption issues such as celiac disease, Crohn’s disease, or bariatric surgery; obesity, which can sequester vitamin D in fat tissue; chronic kidney or liver disease, which impairs vitamin D activation; certain medications (like steroids, anticonvulsants, or some cholesterol drugs); and seasonal factors that reduce UVB exposure, all of which can contribute to deficiency.
25 Reasons Humans Need Vitamin D:
1. Supports calcium absorption
2. Builds strong bones
3. Prevents osteoporosis
4. Maintains healthy teeth
5. Supports muscle strength
6. Reduces fall risk in older adults
7. ***Supports immune system function***
8. Helps fight respiratory infections
9. Modulates inflammation
10. Supports heart health
11. Helps regulate blood pressure
12. Supports insulin sensitivity
13. Helps regulate blood sugar
14. Supports brain function
15. Plays a role in mood regulation
16. Supports nervous system health
17. Aids hormone balance
18. Supports thyroid function
19. Supports healthy prregnancy
20. Important for fetal bone development
21. Supports cellular growth and repair
22. Plays a role in gene expression
23. May help regulate autoimmune responses
24. Supports gut health and microbiome balance
25. Linked to overall longevity and wellness
Protection Against Viruses
(Citations listed at end)
Vitamin D helps protect against flu and COVID mainly by supporting how your immune system recognizes, responds to, and controls infections.
Here’s how it works, step by step:
1. Strengthens the innate immune system
Vitamin D activates antimicrobial peptides (like cathelicidin and defensins) that help kill viruses early, before they spread.
2. Improves first-line defense in the lungs
Vitamin D supports the immune cells lining the respiratory tract, making it harder for viruses to gain a foothold.
3. Reduces viral replication
Lab and clinical studies show vitamin D can limit how efficiently viruses replicate inside cells.
4. Modulates immune response (prevents overreaction)
Vitamin D helps prevent an excessive inflammatory response, sometimes called a cytokine storm, which is linked to severe COVID and flu complications.
5. Lowers inflammatory cytokines
It reduces pro-inflammatory markers like IL-6 and TNF-α, which are elevated in severe viral infections
6. Supports adaptive immunity
Vitamin D helps regulate T cells and B cells, improving targeted immune responses without excessive inflammation.
7. Improves immune balance
It shifts the immune system toward a balanced response—strong enough to fight infection, controlled enough to avoid tissue damage.
8. Helps maintain healthy mucosal barriers
Vitamin D supports the integrity of lung and airway barriers, reducing viral penetration.
9. Associated with reduced severity
Low vitamin D levels are consistently associated with:
Higher infection risk
Worse outcomes
Increased hospitalization
Higher mortality in respiratory infections
10. Supports recovery
Adequate vitamin D levels are linked to shorter illness duration and improved recovery in respiratory viral infections.
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Important clarification
Vitamin D is not a cure and not a replacement for medical treatment, but it plays a supportive, preventative role in immune resilience.
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And here's something important to hear. We may not be getting enough in supplementation: https://youtu.be/AtoxkK7MeKc?si=ioeVSqh8g_WSbCTA
Citations:
https://link.springer.com/article/10.1186/s40795-025-01060-y
https://pubmed.ncbi.nlm.nih.gov/37571407/
https://pubmed.ncbi.nlm.nih.gov/36829806/
https://pubmed.ncbi.nlm.nih.gov/39861407/
https://www.healthline.com/health/food-nutrition/benefits-vitamin-d