Livestock are fattened with B vitamins to increase their metabolic efficiency, yielding more weight from less feed. For human weight loss, metabolic *inefficiency* is desirable. The widespread fortification of foods with B vitamins may inadvertently make our bodies better at storing calories as fat.

Most Vitamin D research fails because it treats it like a drug, giving everyone a fixed dose. As a hormone, Vitamin D requires personalized dosing to achieve a specific blood level, just like thyroid or testosterone. This methodological flaw explains the conflicting results in many studies.

Over-the-counter melatonin is a hormone, not a simple vitamin. As a circadian pacemaker, it can affect every system in the body and is known to interfere with critical medications, including birth control, antidepressants, and treatments for diabetes and heart conditions.

The biohacking movement's focus on interventions like supplements is flawed without first tracking baseline data. To truly "hack" health, one must measure their normal state to see if interventions are effective. Otherwise, it's impossible to know which of the dozens of changes are actually working.

Restoring a damaged gut microbiome isn't just about probiotics; it requires providing its necessary growth factors. A short, three-month course of B-complex vitamins can "jump-start" the right bacteria. After this, supplementation should cease, allowing the now-healthy microbiome to take over B-vitamin production.

Supplementing with Vitamin D can accelerate the body's repair systems. This increased metabolic activity consumes more B vitamins, potentially leading to a deficiency if not also addressed. This can cause new symptoms like joint pain or burning sensations.

Clinical trials show that supplementing with B vitamins to lower homocysteine provides no cognitive benefit if Omega-3 levels are low. Conversely, Omega-3 supplementation is ineffective if homocysteine is high. This demonstrates a critical nutrient synergy essential for brain health.

Vitamin D functions like a hormone by entering a cell's nucleus to trigger DNA expression. This misclassification has led to misunderstandings about its importance and proper management, which should be based on blood levels like other hormones, not fixed doses.

Melatonin is a hormone, not a simple sleep aid. Studies show over-the-counter products can contain 0% to 667% of the listed dose. It dangerously interacts with SSRIs and birth control, and high doses can act as a contraceptive, potentially disrupting puberty in children.