How long does it take for a daily supplement to work? An honest timeline

One of the most common lines in supplement reviews, across every brand, is some version of "been taking it three weeks and I can't feel any difference". It's an honest complaint and it deserves an honest answer, because half of it is about expectations that were set wrong in the first place.

What a supplement is for

A food supplement tops up nutrients you may not be getting enough of from food. That's the legal definition and it's also the practical one. In Great Britain a supplement may only carry health claims that are on the GB Nutrition and Health Claims Register, and nearly all of those are worded "contributes to normal ..." something: normal energy-yielding metabolism, normal psychological function, normal function of the immune system. "Normal" is the key word. The claims describe a nutrient helping your body do what it already does when you have enough of that nutrient. They are not promises that you will feel a rush.

What you should not expect

• Weight loss. No vitamin, mineral or greens powder makes you lose weight. Meal replacement shakes work by replacing calories, not by magic. If a product implies otherwise, it is outside the rules.
• A stimulant hit. If a powder gives you a noticeable buzz within an hour, it contains caffeine or a similar stimulant. VH Life contains neither.
• Treatment of a condition. Supplements don't treat IBS, menopause, anaemia or anything else. Deficiencies are diagnosed and treated by a GP.

A realistic timeline

Day one. Hydration is the only thing you can plausibly notice on day one, because you've just drunk half a litre of water with electrolytes. Water "contributes to the maintenance of normal physical and cognitive functions" at two litres a day. That is an authorised claim and a lot of people are simply under-hydrated.

Weeks one to two. Your gut adjusts to any fibre and plant powders. Some people get more gas, then it settles. Nothing else to feel yet.

Weeks four to twelve. This is where blood levels of water-soluble vitamins and minerals reach a steady state. If you were low in something, this is when the difference would show, and it usually shows as the absence of a problem rather than the presence of a feeling: fewer afternoon slumps, for example, which is what the authorised claim "contributes to a reduction of tiredness and fatigue" (vitamins B6, B12, C, folate, niacin, pantothenic acid, magnesium) describes.

Three months plus. Slow-turnover tissues. Hair grows about a centimetre a month and nails take around six months to replace, so the biotin and zinc claims ("maintenance of normal hair", "normal skin", "normal nails") are not something to judge in a fortnight.

If you were not short of anything

Here is the part most brands won't say: if your diet already covers your nutrient needs, a supplement will not make you feel better than fine. You may feel exactly the same. That's not the product failing, it's the product having nothing to top up. The people who notice most are usually those who were eating badly, sleeping badly or drinking too little water, and the water and routine did a lot of the work.

How to judge it fairly

Give it eight to twelve weeks, take it every day at the same time, keep the rest of your life roughly the same, and pay attention to what stops happening rather than what starts. If you've done that and feel nothing, it's fine to stop; there is no lock-in on VH Life and no subscription pressure. The 7-sachet trial exists precisely so you don't have to commit £35 to find out.

VH Life is a food supplement. It is not a substitute for a varied, balanced diet and a healthy lifestyle, and it does not treat, prevent or cure anything. Adults only. Not for children, adolescents, or anyone pregnant or breastfeeding. If you take medication, in particular anticoagulants or antiplatelet medicines, speak to your doctor before use.