1 December 2006

GI News Briefs

Two matters of the heart

1. Low carb and heart health
‘A heart-healthy diet should embrace healthy types of fat and carbohydrates,’ said Frank B. Hu commenting on the findings of the first study to look at the long-term effects of low-carb diets published in the New England Journal of Medicine. The researchers from the Harvard School of Public Health looked at data collected over a 20-year period from 82,802 women in the Nurses’ Health Study. They found no evidence of an association between low-carb diets and an increased risk of coronary heart disease (CHD) in women. When vegetable sources of fat and protein (see below) were chosen rather than animal sources, they report that ‘these diets may moderately reduce the risk of coronary heart disease.’ The authors highlighted a link between glycemic load and CHD. ‘A low-carbohydrate diet tends to have a lower dietary glycemic index and glycemic load than a high-carbohydrate diet,’ explained the researchers. ‘We found that the direct association between glycemic load and coronary heart disease was much stronger than the association between carbohydrate and coronary heart disease, probably because glycemic load reflects both the quantity and quality of carbohydrates.’ In a press release about the findings, Hu says: ‘This study doesn’t mean that you should load your plate with steak and bacon. One likely explanation that we did not see increased risk of CHD with low-carbohydrate diets is that the adverse effects of animal products might be counterbalanced by reducing refined carbohydrates. The quality of fat and carbohydrate is more important than quantity.’
New England Journal of Medicine (Vol. 355, pp. 1991-2002)
– Harvard School of Public Health press release: www.hsph.harvard.edu

Coronary heart disease

GI Group: How much protein can you get from plants?

  • 200 g (7 oz) of home-cooked or canned beans, lentils or chickpeas provide an average of 15 g protein
  • 200 g (7 oz) soy beans or soy products provide around 24 g protein
  • 100 g (3½ oz) tofu provides around 10 g protein
  • a cup of brown rice provides around 6 g protein
  • a slice of mixed-grain bread or 30 g (1 oz) raw rolled oats provide around 3 g
  • a 30 g (1 oz) serving of most nuts or seeds will deliver around 5 g protein
2. Fruit and veg – it’s a numbers game
Every extra of fruit or vegetable consumed daily could cut the risk of heart disease by 4 per cent, says a meta-analysis of almost a quarter of a million people published in the Journal of Nutrition (Vol. 136, pp. 2588-2593). Scientists from France’s INSERM in Paris, Lille’s Pasteur Institute, and Rouen’s Department of Epidemiology and Public Health pooled nine cohort studies giving an overall study population of 91,379 men, 129,701 women, and 5,007 coronary heart disease events. They report that the risk of coronary heart disease (CHD), was cut by 4% for each additional fruit and vegetable portion consumed, and by 7% for fruit portion intake. The link between the risk of CHD and vegetable intake however was mixed with a more beneficial relationship observed for general cardiovascular mortality (26% risk reduction) than for the more specific fatal and non-fatal heart attacks (myocardial infarction) (5%).
Journal of Nutrition (Vol. 136, pp. 2588-2593)


GI Group: If you are wondering what a meta-analysis is, think of a it as being a way of looking at all the evidence statistically by integrating the results of several independent smaller studies.

PCOS prevalence
PCOS is one of the most common hormonal disorders affecting pre-menopausal women and the leading cause of female infertility. Because insulin resistance is at the root of PCOS, women with it are at greater than average risk of other chronic diseases that will have a huge impact on their long-term health and wellbeing – diabetes, metabolic syndrome and heart disease. No one really knows how many women actually have PCOS. It tends to be under-diagnosed because many women consult their doctor (or doctors) about a variety of very different symptoms (See October GI News), and the dots never get joined. Figures like 5–10% are widely quoted. But this may be just the tip of the iceberg.

A new Spanish prospective study of pre-menopausal Spanish women published in Archives of Internal Medicine puts the figure at 28.3% for those who are already overweight or obese. Francisco Álvarez-Blasco, MD, of the Hospital Universitario Ramón y Cajal and colleagues recruited 113 otherwise healthy women referred by their primary physicians to an outpatient endocrinology clinic for dietary treatment. All participants were pre-menopausal, had a body mass index above 25 and were younger than 50. Of 113 women recruited, 32 were diagnosed as having PCOS, based on clinical and/or biochemical hyperandrogenism, oligo-ovulation, and exclusion of secondary causes. ‘Our results demonstrate a 28.3% prevalence of PCOS in overweight and obese women from Spain, which is markedly increased compared with the 5.5% prevalence of PCOS in lean women of our country,’ they write. But even this figure may underestimate the prevalence of PCOS as women on medications that might interfere with hormone profiles, such as contraceptives or insulin sensitisers, were excluded.

‘Physicians treating overweight and obese patients should be aware of the high prevalence of PCOS among these women,’ conclude the authors. They call for routine screening of overweight or obese women for PCOS, ‘at least by obtaining a detailed menstrual history and a careful clinical evaluation of hyperandrogenic symptoms … to diagnose PCOS and ameliorate the health burden distinctly associated with this prevalent disorder.’
Archives of Internal Medicine. 2006; 166:2081-2086


Anonymous said...

Some studies suggest that many women with PCOS can be helped with supplementing fish oil, also with Vitamin D, calcium and magnesium. Peggy L Manuel, MD, FAAP
PS I love your GI newsletter. I wish we had more labels on food products here in USA. Thanks for all your excellent research on GI/GL.

beruang said...

it seems that the authors cited in the first article (low carb & heart health) got a bit mixed up about low carb vs low GI, especially at the beginning. what do you think? when i read through the article i was thinking that they were talking about low GI carb, rather than 'low amount of carb'. so i suppose they should have used the term 'high (complex) carbohydrate low GI' rather than 'low carb'.

beruang said...

whoops sorry. it turns out that these authors ARE actually talking about 'real' low carb (and actually plant based) diet.