A plain daily multivitamin at conservative amounts. It exists because vitamin D and B12 are the two shortfalls that show up most in Western diets, and because zinc and magnesium are the minerals people most often miss without noticing. If you only take one thing, this is the least exciting and most defensible choice.

Thiamin, riboflavin, niacin, B6, B12 and pantothenic acid are the cofactors in the reactions that turn food into usable energy. That is what they do; it is not a promise that you will feel different. Topping up a B vitamin you already have enough of does nothing — the effect is in correcting a shortfall. Deliberately contains no iron: iron is worth taking on evidence of a deficiency, not on a feeling of tiredness.

Magnesium is involved in normal muscle and nerve function and B6 in making several neurotransmitters. The evidence that supplementing either improves sleep in people who are not short of them is weak, and we would rather say so than sell you a promise. If you sleep badly, the sleep diary in this app and a conversation with a clinician will do more than a capsule.

EPA and DHA are structural fats concentrated in the brain and retina, choline is used to make acetylcholine, and B12 keeps nerve cells working. Those are roles, not results. Nothing here is a treatment for memory problems, and memory changes that worry you belong with a clinician rather than a supplement.

These four are the nutrients most often studied alongside low mood, largely because a shortfall in any of them is common and worth ruling out. That is a reason to make sure you are not short; it is not evidence that taking more helps if you are not. **This is not a treatment for depression.** If your mood is a problem, talk to someone — there are crisis numbers on the care pages, and they are a better first call than this.

Sustained stress tends to come with worse eating rather than a higher nutrient requirement, and this pack is aimed at the first of those. The B vitamins and magnesium are cofactors in energy metabolism and nerve function; vitamin C is used to make collagen and is depleted quickly. It will not make a stressful period less stressful.

Zinc is involved in maintaining the gut lining and the B vitamins in digestive enzyme function. Being straight about the limits: the things that most affect digestion are fibre, water, sleep and what you actually eat, and none of those comes in a capsule. We do not sell probiotics, and this pack is not a substitute for one or for seeing someone about persistent symptoms.

Vitamin C is required to make collagen, zinc is involved in wound healing, and biotin is a cofactor in building fatty acids. Worth knowing before you buy: biotin supplements are the classic case of a nutrient that helps visibly only if you were deficient, which is rare. Worth knowing before a blood test: **high-dose biotin interferes with thyroid and troponin assays** — tell whoever takes your blood that you take it.

**No supplement here causes weight loss, and this one does not either.** What it is for is the actual nutritional risk of eating less: when total intake drops, micronutrient intake drops with it, and the gaps show up first in iodine, B12, vitamin D and the minerals. This is a plain multivitamin sold honestly for that, and nothing else. Anyone selling you a capsule that burns fat is selling you something that does not work.

Magnesium is part of normal muscle function, vitamin D of muscle strength, vitamin C of making collagen for connective tissue, and zinc of wound healing. Being straight about the order of things: **protein, calories and sleep do far more for training than any of this**, and the drink mixes below cover protein and creatine, which have better evidence than anything in a capsule here. This is the small stuff, sold as the small stuff.

Calcium is the mineral bone is built from, vitamin D lets the gut absorb it, vitamin K activates the proteins that bind it into bone, and magnesium is part of the structure. The calcium here is half an adult requirement on purpose — most people get a good share from food, and the two together should not exceed what you need. **Vitamin K interacts directly with warfarin**; if you take it, this pack is not for you without asking first.

All four are involved in normal immune function, and a shortfall in any of them measurably impairs it. That is the honest claim. The stronger one people expect — that taking these prevents colds — is not supported for people who are not deficient, and we are not going to make it.