Just yesterday I was being consulted by an individual keen to lose weight who was neither sedentary nor ate a rubbish diet. In fact, her diet was what I would call ‘restrained’. It’s easy to be cynical about individuals like this, and just assume that they are eating more than they think or simply not fessing up to the reality of their dietary intake. While I am sure this sort of thing happens, my first instinct is to take an individual at face value, and explore why that individual might be experiencing a body weight that appears to be disproportionate to their food intake and activity habits.
One explanation for this, of course, is that an individual’s metabolism may be on the sluggish side. Even a slightly muted metabolism could, in time, lead to a considerable gain in weight. On the up side, boosting metabolism may make it easier for individuals to lose and maintain a healthy weight.
With this in mind, my attention was caught be a recent study published in the Journal of the American College of Nutrition [1]. It involved the feeding of overweight men with a compound known as epigallocatechin-3-gallate (EGCG). This substance, a component of tea and green tea, has been said to have the ability to stimulate weight loss by boosting the body’s metabolism.
In the study in question, overweight men were treated with 300 mg of EGCG or placebo for just two days. Compared to placebo, the EGCG did not appear to increase the metabolic rate at rest. However, the study did find evidence that the EGCG stimulated the metabolism of fat after a meal. This effect might, of course, give EGCG and the foodstuffs that contain it some ability to reduce fatty accumulation in the body.
As it happens, there is some evidence to support this too. In one study, overweight men were asked to drink catechin-rich (EGCG is part of a group of compounds referred to as ‘catechins’) tea or low-catechin tea for 12 weeks [2]. The catechin-rich tea led to significant reductions in body weight, waist size and fat mass. The total catechin amount supplied by the ‘active’ tea was 690 mg a day ” which equates to about 5-6 cups of green tea [3].
The other thing about catechins is that they appear to have ‘antioxidant’ and other properties that would be expected to help ward of chronic disease including cancer (see below).
The evidence suggests that regular consumption of green tea is likely to have benefits for health, and might even aid weight loss in individuals whose metabolisms could do with a bit of a ‘pick-me-up’,
References:
1. Boschmann M, et al. The Effects of Epigallocatechin-3-Gallate on Thermogenesis and Fat Oxidation in Obese Men: A Pilot Study. Journal of the American College of Nutrition 2007;26(4):389S-395S
2. Nagao T, et al. Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men. American Journal of Clinical Nutrition 2005;81(1):122-129
3. Khokhar S, et al. Total phenol, catechin, and caffeine contents of teas commonly consumed in the United Kingdom. J Agric Food Chem. 2002;50(3):565-70.
More research suggests that green tea has cancer-protective properties – 27 December 2006
In previous blogs, I have reported on the apparent health-benefits of green tea, and in particular its apparent association with a reduced risk of cancer. This beverage is rich in phytochemicals (naturally-occurring plant substances) known as polyphenols that have what is known as ‘antioxidant’ activity. This means that they have the potential to quell disease-promoting molecules known as free radicals in the body.
In a recent study published on-line in the journal Carcinogenesis, the association between green tea drinking and breast cancer was assessed [1]. In this study, green tea drinkers, compared to non-drinkers, tended to be different for other reasons including a tendency to consume more fruits and vegetables (probably protective for breast cancer) and alcohol (which probably increases cancer risk). In this study, these and other factors (known as ‘confounding factors’) were taken account of in an attempt to make as accurate an assessment as possible regarding the actual association between green tea drinking and breast cancer.
This study found that women consuming 750 grams or more of green tea leaves each year were at a 39 per cent reduced risk of breast cancer compared to non-drinkers. Each cup of green tea is generally made with a teaspoon (about 2.5 grams) of leaves. 750 grams of dried leaves per day equates to only 300 cups of green tea over the course of a year: less than one each day.
So-called ‘epidemiological’ studies of this sort can never be used to ‘prove’ that green tea protects against breast cancer. However, the fact that this study took account of common confounding factors strengthens its findings. Also, green tea is known to contain substances that one would expect might help to protect the body from cancer. One particular polyphenol offered by green tea that has attracted particular attention is known as epigallocatechin gallate (EGCG). EGCG has been found to have a number of cancer-protective actions in the body, including an ability to help in the deactivation of cancer-causing chemicals (carcinogens).
Take all of this into consideration, as well as previous research linking green tea with cancer protection, and there seems to be pretty good reason to think that green tea has potential benefits in this respect.
References:
1. Zhang M, et al. Green tea and the prevention of breast cancer: a case-control study in southeast China. Carcinogenesis. 2006 December 20 [Epub ahead of print]
