Fireblood Blog — Supplement Science & Ingredient Guides

Close-up of sunflower seeds in the shell on a dark background
Foods rich in vitamin B1 (thiamine): 22 ranked per 100g
The foods richest in vitamin B1, ranked per 100g from USDA data. Pork beats beef 11 to 1, seeds lead the plants, and roasting cuts the numbers hard. Read more...
Vitamin tablets and capsules spilling from a bottle onto a dark surface, what vitamins should I take
What vitamins should I take? Start with these gaps
What vitamins should you take? Start with vitamin D in winter, then check magnesium, vitamins E, A and C. B12 if you're vegan or older. Read more...
Scoop of white amino acid powder held over an open supplement tub
Best essential amino acid supplement: 6 label checks
The best essential amino acid supplement lists all 9 EAAs with doses and 700mg+ leucine. 6 label checks, and when food does the job for less. Read more...
Older man with a grey beard in profile against a black background
Best multivitamin for men over 60: what the trials tested
The best multivitamin for men over 60 is a plain daily multi with no iron and free-form B12. What PHS II and COSMOS found, and what to skip. Read more...
A single mandarin orange on a black background
Vitamin C deficiency symptoms: the signs, in the order they appear
Vitamin C deficiency symptoms start with fatigue and low mood, then gums, skin and joints. The signs in order, who runs low, and how to fix it. Read more...
Close-up of brown kelp blades drying in Hokkaido, Japan. Seaweed is the food highest in iodine
What food is highest in iodine? Seaweed, then white fish
Seaweed tops the list, but baked cod gives 172mcg of iodine per 100g, more than a day's need. 26 foods ranked from the USDA iodine database. Read more...
A pile of dried red apricots, one of the richest fruit sources of potassium
Potassium deficiency symptoms: 6 signs and real causes
Potassium deficiency symptoms: weakness, cramps, fatigue, palpitations. Why low potassium usually comes from losses, and what to check first. Read more...
Zinc metal fragments and a 1cm zinc cube
Best form of zinc for colds: what the trials show
Zinc acetate lozenges at 75 to 100mg a day cut colds by about a third. Which forms work, which to avoid, and why daily zinc will not prevent one. Read more...
A loaded barbell on a dark gym floor, the kind of training an athlete multivitamin has to support
Best multivitamin for athletes: 6 things it has to cover
What an athlete's multivitamin actually needs: sweat-lost minerals, B vitamins in active forms, and the one ingredient it should leave out. Read more...
Two fresh spinach leaves with water droplets on a dark slate surface
Folate deficiency symptoms: what shows up first
Folate deficiency causes fatigue, a sore red tongue and mouth ulcers. UK folate levels have fallen since 2008. What to check and what to do. Read more...
Dark leafy greens including curly kale, the top food source of vitamin K1
What food is highest in vitamin K? K1 and K2 ranked
Natto tops vitamin K2. Collard greens and spinach top K1. The ranked list with USDA numbers, plus how much vitamin K you actually need. Read more...
Assorted supplement tablets and capsules spilled from a white bottle onto a dark textured surface
Best time to take vitamin B12 (and what matters more)
Morning with breakfast is the practical answer. But dose size and the gap between doses change your B12 levels far more than the clock. Read more...