Fireblood Blog — Supplement Science & Ingredient Guides

Red and yellow bell peppers on a dark slate surface
Best food sources of vitamin C: 10 ranked, and where the orange lands
The best food sources of vitamin C ranked by mg per 100g of USDA data. Where the orange really lands, what boiling costs, and how much you need. Read more...
Almonds in a black bowl on dark marble, one of the richest food sources of vitamin E
What is vitamin E best for? One job, done well
Vitamin E has one proven job: protecting the fats in your cell membranes from oxidation. What the trials found, how much you need, and what to ignore. Read more...
Gold blister pack and loose capsules on a black surface
Best multivitamin for men over 40: the age gate is marketing
Every RDA for men is identical from 31 to 50. What actually changes at 40, what to look for on a label, and what the over-40 tag is selling. Read more...
Supplement tablets spilling from a bottle onto a dark surface
Magnesium glycinate vs citrate: what the data shows
Glycinate has the reputation. Citrate has the human trials. What the absorption data actually shows, and which magnesium form fits which person. Read more...
Quail eggs in a wooden bowl on a dark surface, a food source of vitamin B2 riboflavin
What is vitamin B2 good for? The honest answer
Vitamin B2 (riboflavin) mainly works by activating other nutrients. What it does, how much you need, and why 37% of adults test low. Read more...
Coarse salt scattered across a dark slate surface with a wooden spoon
Iodine deficiency symptoms: 7 signs to check
Iodine deficiency runs through the thyroid: fatigue, cold intolerance, weight gain, neck swelling. What the data shows and how much you actually need. Read more...
Close-up of a person's hands in low light, fingertips touching
Vitamin B12 deficiency symptoms: the nerve signs that come first
B12 deficiency often shows in the nerves before the blood. Tingling, numbness and balance changes can appear with a completely normal blood count. Read more...
Raw salmon fillet being sliced on a dark stone surface
Foods high in vitamin D: 8 ranked, and why the list is short
Foods high in vitamin D, ranked by measured IU per 100g. Why the list is so short, the farmed salmon catch, and what cooking takes back. Read more...
Loaded barbell resting on a dark gym floor, creatine for women over 30
Creatine for women over 30: what the evidence shows
Creatine for women over 30: the dose, what the trials found in female subgroups, and where the evidence is thinner than the marketing. Read more...
Multivitamin pills spilled from a white bottle on a dark surface
Are multivitamins worth it? What the trials show
Most multivitamins are not worth it. The trial data shows who benefits, who wastes money, and the label markers that separate the two. Read more...
A single cup of coffee on a dark scratched concrete surface
Caffeine free energy supplement: why we left it out
We do not put caffeine in Fireblood. What caffeine actually does, why it is not energy, and what a caffeine free supplement can really fix. Read more...
Close-up macro of a human iris and pupil on a black background
Vitamin A deficiency symptoms: what shows up first
Night vision that fades, dry eyes, repeat infections. The real vitamin A deficiency symptoms, why 34% fall short, and what to do about it. Read more...