SciTec Water Cut

Herbal 'water' blend (dandelion, parsley, juniper, etc.)· evidence: Insufficient

'Water' or 'cutting' products combine herbs such as dandelion, parsley, juniper, artichoke and cranberry, which have traditionally been used to increase urine flow. Only a handful of very small human studies exist; one short study of dandelion leaf found a small, temporary increase in urination.

Any water lost this way is not fat and comes straight back when you eat and drink normally. These are botanicals, and botanical health claims are not authorised in the UK, so we make no claims about what they do. Persistent swelling or water retention should be checked by a GP.

Typical dose: No established dose; products vary widely

Safety: Do not use to make weight for a competition without medical supervision: dehydration is dangerous. Speak to your GP first if you take diuretics, lithium, blood pressure or diabetes medicine, or have kidney, heart or liver disease. Juniper and parsley extracts are not suitable in pregnancy. Avoid dandelion if you are allergic to ragweed, daisies or related plants.

Research we looked at:
Clare BA, Conroy RS, Spelman K (2009). The diuretic effect in human subjects of an extract of Taraxacum officinale folium over a single day. J Altern Complement Med 15(8):929–934.
NHS. Oedema (swelling) (nhs.uk).

Green tea extract· evidence: Limited

Green tea extract contains catechins (mainly EGCG) and usually some caffeine. Studies have looked at whether it raises the energy the body uses. A Cochrane review found any effect on weight in overweight adults was very small, around a kilogram or less, and not clinically important. Much of the small effect seen may come from the caffeine.

Green tea is a botanical, and botanical health claims are not authorised in the UK, so we make no claims about what it does. It is not a substitute for eating less and moving more.

Typical dose: Products usually give 100–500 mg extract a day; check the label for EGCG and caffeine content

Safety: Concentrated green tea catechins have been linked to rare cases of liver damage. EFSA found that 800 mg or more of EGCG a day from supplements was linked to raised liver enzymes. Take with food, do not exceed the label dose, and stop and see a doctor if you notice dark urine, yellowing skin or eyes, or abdominal pain. Contains caffeine unless decaffeinated; count it in your daily total. Not for pregnancy, breastfeeding or under-18s.

Research we looked at:
Jurgens TM et al. (2012). Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database Syst Rev (12):CD008650.
EFSA ANS Panel (2018). Scientific opinion on the safety of green tea catechins. EFSA Journal 16(4):5239.

Vitamin C· evidence: Moderate

Vitamin C (ascorbic acid, or mineral ascorbates such as sodium, calcium or magnesium ascorbate) is an essential vitamin found in fruit and vegetables. Adults need about 40 mg a day in the UK, and most people who eat fruit and vegetables get enough. The body cannot store much, and absorption falls off at higher doses, so the extra from a 1,000 mg tablet is largely passed in urine.

The best evidence on colds (a Cochrane review) found that taking vitamin C every day does not stop most people catching colds, but may shorten them slightly. People doing very heavy physical exercise are the exception, where regular vitamin C roughly halved the number of colds in trials.

A supplement makes sense if your diet is low in fruit and vegetables, if you smoke, or around periods of hard training. Most people do not need mega-doses, and fancy forms (liposomal, ester or buffered) have little evidence of meaningful benefit over plain ascorbic acid, though buffered forms can be gentler on the stomach.

Typical dose: The UK reference intake for adults is 40 mg a day (NRV on labels: 80 mg). Supplements commonly give 200 to 1,000 mg.

Safety: The FSA advises that 1,000 mg (1 g) a day or less from supplements is unlikely to cause harm. Higher doses can cause stomach pain, diarrhoea and wind. People with a history of kidney stones, haemochromatosis (iron overload) or kidney disease should speak to their GP before taking high doses. Chewable and powder forms are acidic and can affect tooth enamel.

Research we looked at:
NHS. Vitamin C. nhs.uk/conditions/vitamins-and-minerals/vitamin-c
Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 2013;(1):CD000980.
EFSA NDA Panel. Scientific opinion on dietary reference values for vitamin C. EFSA Journal 2013;11(11):3418.
Carr AC, Vissers MCM. Synthetic or food-derived vitamin C: are they equally bioavailable? Nutrients 2013;5(11):4284-4304.

Cost per daily dose lets you compare packs of different sizes fairly.Worked out from our current prices.