The proof: Although some studies suggest that dietary carnitine (found in red meat and dairy products) has the potential to stimulate fat metabolism (Nutrition, 2004; 20: 709-15), there’s little evidence to show that carnitine supplements are effective for weight loss. In fact, one Australian study found that eight weeks of l-carnitine supplementation combined with aerobic training failed to promote weight loss in moderately obese women (Int J Sport Nutr Exerc Metab, 2000; 10: 199-207). Similarly, a review of several popular weight-loss supplements reported that “no trials demonstrate that l-carnitine is effective for weight loss” (Am Fam Physician, 2004; 70: 1731-8).
- Precautions: l-Carnitine appears to be safe, although the Australian study mentioned above reported nausea and diarrhoea in some people taking the supplement that was sufficient to cause them to drop out of the study.
Hydroxycitric acid
- The pill: Hydroxycitric acid (HCA), found in the Malabar tamarind fruit (Garcinia cambogia), has been used for centuries in Southeast Asia to make meals more filling. Today, it’s marketed as a weight-loss supplement either alone or in combination with other ingredients.
- The promise: HCA purportedly aids weight loss by suppressing the appetite and reducing the conversion of carbohydrates into stored fat.
- The proof: The good news is that some placebo-controlled studies have found that HCA can increase weight loss, reduce appetite (Int J Obes, 1997; 21 [Suppl 2]: S61; Diabetes Obes Metab, 2004; 6: 171-80), cut calorie intake (Int J Obes Relat Metab Disord, 2002; 26: 870-2) and increase fat-burning in athletes (J Nutr Sci Vitaminol [Tokyo], 2002; 48: 128-33). Moreover, one study reported increased weight loss after treatment with HCA plus chromium (Am J Bariatr Med, 1993; Summer: 17-9).However, several other studies have not confirmed these proposed effects. In one of the largest and most rigorous trials, researchers found no significant differences in weight loss or body fat mass between those taking HCA and those taking a placebo (JAMA, 1998; 280: 1596-600). There is, nevertheless, some evidence to suggest that HCA effectiveness may depend on the dose and type of HCA formulation used. For example, in rat studies, Dutch scientists found that the HCA-based products Citrin K and Regulator were significantly more effective than Super CitriMax HCA-600-SXS at reducing food intake, despite using the same dosages (150 and 300 mg/kg) of each product (Nutr Metab [Lond], 2005; 2: 23). But these results may not apply to humans.
- Precautions: Side-effects associated with HCA include headache, nausea and gastrointestinal symptoms. However, in most of the trials, there were no significant differences in adverse events between HCA and placebo (J Obes, 2011; 2011: 509038; doi:10.1155/2011/509038).
Pyruvate
- The pill: Pyruvate is a three-carbon compound made in our bodies as a result of glucose metabolism. It’s also found naturally in foods (such as apples), as well as in slimming and sports supplements.
- The promise: Pyruvate can supposedly reduce body fat and enhance the body’s ability to use energy efficiently.
- The proof: Several studies have suggested that pyruvate might be useful for weight loss and for improving body composition. In one randomized controlled trial, high-dose pyruvate supplements (22-44 g/day) enhanced weight loss and led to a greater reduction of body fat in overweight adults consuming a low-fat diet (Am J Clin Nutr, 1994; 59: 423-7).In another study, a much lower dose of pyruvate appeared to have similar effects. A group of overweight men and women were randomly assigned to receive either 6 g/day of pyruvate or a placebo for six weeks. In addition, all participants took part in an exercise programme that consisted of a 45- to 60-minute aerobic/anaerobic routine three days a week. The results showed a significant reduction in body weight and body fat in the pyruvate group (Nutrition, 1999; 15: 337-40). According to a recent review published in the Journal of Obesity, the evidence so far suggests that pyruvate “may be beneficial for weight loss”, and appears to work via fat-modifying mechanisms. However, the researchers point out that the trials conducted so far have had small sample sizes and lasted for only short periods of time (J Obes, 2011; 2011: pii: 297315; Epub 2010 Aug 10).
- Precautions: Studies suggest that pyruvate is generally well tolerated, with gastrointestinal upset (such as wind, bloating and diarrhoea) being the most common side-effect. One preliminary study involving women who exercised found t
hat 10 g/day of pyruvate reduced blood levels of ‘good’ HDL cholesterol after just one month (Med Sci Sports Exerc, 1998; 30: S155).
Joanna Evans
Factfile: What is atrial fibrillation?
Atrial fibrillation (AF), the most common type of cardiac arrhythmia (irregular heart beat), involves the two upper chambers (atria) of the heart. Although some people with AF experience no symptoms at all, others suffer from fatigue, confusion, shortness of breath, chest pain and palpitations.
While not immediately life-threatening, AF can increase the risk of stroke or heart failure. Recent evidence suggests that AF sufferers also have an elevated risk of Alzheimer’s disease and other types of dementia (J Am Geriatr Soc, 2011 Aug 1; doi: 10.1111/j. 1532-5415.2011.03508.x).
Abnormalities or damage to the heart’s structure are the most common reasons for AF. Other possible causes include high blood pressure, heart attack, congenital heart defects, heart surgery, overactive thyroid gland, exposure to stimulants such as medications, caffeine or tobacco, and viral infections. Some people with AF, however, don’t have any heart defects or damage and the cause is often unclear. This is known as ‘lone’ AF.
Conventional treatment of AF varies, depending on factors such as age, severity of symptoms and whether there’s an under-lying cause. Usually, a combination of anti-arrhythmic and anticoagulant drugs are prescribed, but these, not surprisingly, come with a host of adverse effects. Tiredness, painful joints, loss of taste, dry skin and pink-coloured urine are just a few that have been reported by WDDTY readers.
