Supplement Guides

Ashwagandha

Ashwagandha (Withania somnifera) is an Ayurvedic herb whose root contains steroidal lactones called withanolides.

Berberine

Berberine is a bitter yellow alkaloid from goldenseal, barberry, Oregon grape, and Chinese goldthread.

Biotin

Biotin deficiency is rare, and the evidence for biotin as a hair and nail treatment comes almost entirely from people who were deficient.

Caffeine

Caffeine blocks adenosine A1 and A2A receptors.

Calcium

Calcium is the mineral of bone, and the skeleton doubles as the body's calcium reservoir, drawn down whenever diet falls short.

Chromium

Trivalent chromium was proposed decades ago as a "glucose tolerance factor" that amplifies insulin signaling.

Coenzyme Q10

Coenzyme Q10 carries electrons from complexes I and II to complex III in the inner mitochondrial membrane, and in its reduced form, ubiquinol, it acts as a lipid-soluble antioxidant.

Collagen

Collagen is the most abundant protein in the body, and collagen supplements are hydrolyzed animal collagen from hides, bones, or fish skin.

Copper

Copper is a cofactor for enzymes that move electrons and iron: cytochrome c oxidase in mitochondria, superoxide dismutase, and ceruloplasmin, which prepares iron for transport.

Creatine

Creatine is made in the liver and kidney from arginine, glycine, and methionine, about 1 g a day, and an omnivorous diet supplies roughly another gram.

DHEA

DHEA is the most abundant circulating steroid in young adults, made mostly by the adrenal glands and converted in tissues into testosterone and estrogens.

Elderberry

Elderberry products are made from the cooked berries of the European black elder, Sambucus nigra, and are sold mainly as syrups and gummies for colds and flu.

Fiber

Dietary fiber is carbohydrate that escapes digestion in the small intestine.

Folate

Folate carries one-carbon units for thymidine and purine synthesis and for the remethylation of homocysteine to methionine.

Glutathione

Glutathione is a three-amino-acid peptide that every cell makes for itself and uses as its main defense against oxidative damage.

Inositol

Inositol is a six-carbon sugar alcohol, and myo-inositol, the form that dominates both the body and the supplement shelf, is the backbone of the second messengers that carry signals for insulin, FSH, and several neurotransmitter receptors.

Iron

Iron carries oxygen in hemoglobin and myoglobin and sits at the active site of cytochromes and other redox enzymes.

L-Theanine

L-theanine is an amino acid found almost only in tea leaves, where it accounts for much of the savory taste of green tea.

Lion's Mane

Lion's mane (Hericium erinaceus) is an edible mushroom with long white spines.

Magnesium

Magnesium is a cofactor in more than 300 enzyme systems, including every reaction that uses ATP, which exists in cells mainly as a magnesium-ATP complex.

Melatonin

Melatonin is secreted by the pineal gland in darkness on a schedule set by the suprachiasmatic nucleus, and light suppresses it.

N-Acetyl Cysteine (NAC)

N-acetylcysteine is an acetylated form of cysteine, the amino acid that limits how fast cells make glutathione.

NMN and NAD+

NAD+ is a coenzyme in every cell's energy metabolism and the fuel that sirtuins and PARP DNA-repair enzymes burn.

Omega-3 (EPA and DHA)

EPA and DHA are long-chain omega-3 fatty acids built into the phospholipids of cell membranes, where they compete with arachidonic acid as substrates for eicosanoids and give rise to pro-resolving lipid mediators.

Potassium

Potassium is the main positive ion inside cells, and the gradient between high intracellular and low extracellular potassium sets the resting voltage of every nerve and muscle cell, the heart included.

Probiotics

A probiotic is a specific live microorganism, tested at a specific dose, for a specific outcome.

Quercetin

Quercetin is a flavonol found in onions, capers, apples, and tea, and one of the most studied plant compounds in the laboratory.

Rhodiola

Rhodiola rosea is a flowering plant of cold, high-altitude regions whose root was used in Scandinavian and Russian folk medicine against fatigue.

Saw Palmetto

Saw palmetto extract is the most widely used herbal remedy for enlarged prostate symptoms, and it does inhibit 5-alpha reductase, the enzyme that converts testosterone to DHT.

Selenium

Selenium is built into about 25 selenoproteins as the amino acid selenocysteine, including the glutathione peroxidases, thioredoxin reductases, and the deiodinases that convert T4 to T3.

Turmeric and Curcumin

Turmeric is a root; curcumin is the yellow pigment that makes up about 3% of it and the compound behind most of the supplement claims.

Vitamin A

Vitamin A comes in two forms: preformed retinol from animal foods and supplements, and provitamin A carotenoids from plants, which the body converts as needed.

Vitamin B12

Cobalamin is a cofactor for exactly two human enzymes: methionine synthase, which remethylates homocysteine and regenerates usable folate, and methylmalonyl-CoA mutase, which feeds odd-chain fatty acids into the citric acid cycle.

Vitamin B6

Pyridoxal 5'-phosphate (PLP), the active form of vitamin B6, is the coenzyme for more than 140 reactions, most of them in amino acid metabolism: transamination, and the decarboxylations that make serotonin, dopamine, GABA, and histamine.

Vitamin C

Ascorbate donates the electrons that prolyl and lysyl hydroxylases need to stabilize collagen, and it serves the enzymes that make norepinephrine and carnitine.

Vitamin D

Vitamin D is a prohormone.

Vitamin E

Vitamin E is a family of eight fat-soluble compounds, four tocopherols and four tocotrienols, of which the liver keeps essentially one: RRR-alpha-tocopherol.

Vitamin K2

Vitamin K is the cofactor for gamma-glutamyl carboxylase, which activates clotting factors in the liver and, outside it, proteins such as osteocalcin in bone and matrix Gla protein in artery walls.

Whey Protein

Whey is the soluble protein left over when casein curdles in cheesemaking.

Zinc

Zinc is a catalytic or structural cofactor for several hundred enzymes, and about one in ten human proteins binds it, including the zinc-finger transcription factors.