OstroVit CLA + Green Tea + L-Carnitine

CLA (conjugated linoleic acid)· evidence: Limited

CLA is a group of fatty acids found in small amounts in meat and dairy; supplements are usually made from safflower or sunflower oil. It is marketed for reducing body fat.

Meta-analyses report an average fat loss of roughly 0.1 kg a week compared with placebo in some trials, and long-term reviews found the effect too small to be clinically meaningful. Results are inconsistent and effects in healthy, lean people are unclear.

There is no authorised health claim for CLA, so we make no claims about its effects.

Typical dose: Studies have typically used 3–4 g a day

Safety: Can cause stomach upset, nausea and loose stools. Some studies have raised concerns about effects on insulin sensitivity and blood fats in people with obesity, so speak to your GP first if you have diabetes or heart disease. Not for pregnancy or breastfeeding.

Research we looked at:
Whigham LD, Watras AC, Schoeller DA (2007). Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr 85(5):1203–1211.
Onakpoya IJ et al. (2012). The efficacy of long-term conjugated linoleic acid (CLA) supplementation on body composition in overweight and obese individuals: a systematic review and meta-analysis of randomized clinical trials. Eur J Nutr 51(2):127–134.

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.

L-carnitine (incl. L-carnitine L-tartrate)· evidence: Limited

L-carnitine helps carry fats into cells to be used for energy. Your body makes its own, and meat and dairy supply more, so healthy people eating a normal diet are not short of it. Taking extra does not appear to raise the amount in muscle much, which is one reason it does not act as a 'fat burner'.

Reviews of the trials report a small average drop in weight (around 1 kg) compared with placebo, mostly in older or overweight people, often alongside a diet. There is little evidence of a meaningful effect on fat loss in healthy, active people with a normal diet. Small studies of L-carnitine L-tartrate have looked at muscle soreness after exercise, with mixed results.

There is no authorised health claim for L-carnitine, so we make no claims about its effects. Fat loss comes from a sustained calorie deficit, not from this ingredient.

Typical dose: Studies have typically used 1–3 g a day; liquids and capsules usually give 0.5–3 g per serving

Safety: Usually well tolerated at up to about 2 g a day. Higher doses can cause stomach upset, diarrhoea and a 'fishy' body odour. Speak to your GP first if you take thyroid medication or warfarin, have kidney disease, or have had seizures. Not recommended in pregnancy or breastfeeding without medical advice.

Research we looked at:
Pooyandjoo M et al. (2016). The effect of (L-)carnitine on weight loss in adults: a systematic review and meta-analysis of randomized controlled trials. Obes Rev 17(10):970–976.
Talenezhad N et al. (2020). Effects of L-carnitine supplementation on weight loss and body composition: a systematic review and meta-analysis of 37 randomized controlled clinical trials with dose-response analysis. Clin Nutr ESPEN 37:9–23.
EFSA NDA Panel (2011). Scientific opinion on the substantiation of health claims related to L-carnitine. EFSA Journal 9(6):2212.