news Probiotic mechanisms revealed There is no doubt that probiotics (supplements of live microorganisms) have a beneficial impact on health. However research on the mechanisms explaining how probiotics work has been slower to emerge. Now, a new paper has been published which brings together evidence showing how probiotics may exert their actions. This includes modulating immune function, impacting on how other microorganisms function and acting on microbial products/food components within the gut. Different probiotics could have different functions depending on their own metabolic properties.
It has been suggested that regular use of probiotics could help to reduce the requirement for antibiotics or some anti-inflammatory drugs. However, more needs to be known about how different combinations of probiotics work together. For more information see: Oelschlaeger TA et al (2009) Int J Med Microbiol [Epub ahead of print].
First opinions on new European health claims The European Food Standards Agency (EFSA) has released a list of opinions on new ‘evidence-based’ health claims. This was the first of a number of planned announcements over the next year. The opinions follow several months of consideration of dossiers put forward by the food industry in response to the 2007 Nutrition and Health Claims regulation. EFSA’s opinions, which need to be approved by the European Commission before becoming law, include favourable decisions on several nutrients and ingredients. These include health maintenance claims on calcium, magnesium and bone health, vitamin A and vision, selenium and spermatogenesis, and zinc and immune function. Several substances were found to have cholesterol-lowering properties including plant stanol esters, linoleic acid, alpha-linolenic acid and beta glucan fibres (found in oats). The omega-3 fatty acids, DHA and EPA, were found to reduce blood pressure and triglycerides. However, most of the proposed health claims were rejected due to a lack of appropriate evidence or insuffi
cient characterisation of active ingredients. Surprisingly, claims on probiotics and soy isoflavones were rejected due to a lack of specific evidence on cause and effect. To see the full list of approved and rejected health claims visit: http://www.efsa.europa.eu/cs/ Satellite
Polyphenols lower blood pressure and cholesterol It is relatively well known that flavonoids, beneficial plant substances from the polyphenol family, may reduce the risk of cardiovascular disease. However, the effects of individual flavonoids such as quercetin are not clear. In a new study, around 100 overweight and obese Germans (25-65 years) were given 150mg/day quercetin (a flavonoid found in apples and onions) or a placebo for six weeks (with a fiveweek washout period between treatments). Quercetin supplementation was associated with a reduction in systolic
blood pressure (by 2.6mmHg), serum high-density lipoprotein and LDL ‘bad’ cholesterol. Although some markers of CVD in this study remained unchanged, quercetin may provide some protection against CVD development. For more information see: Egert S et al (2009) British Journal of Nutrition Vol 102: pg 1065-74.
Omega-3s and obesity It is now clear that long-chain omega-3 polyunsaturated (LCn3 PUFA) fats such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) play a key role in the maintenance of good health.
Higher levels of adipose tissue can increase the risk of metabolic syndrome (a combination of medical conditions that may be detrimental to health). It is thought that higher intakes of LC-n3 PUFA cause a ‘metabolic switch’, promoting lipid breakdown rather than synthesis. LC-n3 PUFA may also improve insulin sensitivity (how the body handles glucose) in patients with type 2 diabetes (Kopecky et al., 2009). Another theory is that LC n-3 PUFA help to mobilise and redistribute body fat, mainly by blocking enzymes involved in fat synthesis (Li et al., 2008). A recently published animal study found that when Wistar rats were fed a diet containing marine n-3 PUFA (rather than lard) this resulted in both a reduction and redistribution of body fat. Visceral fat (fat around internal organs) was reduced at the end of the sevenweek study. In addition, the expression of genes encoding cytokine and chemokine function (proteins released in times of inflammation/ infection) was improved (RoklingAndersen et al, 2009). More detailed studies are now needed to further understand how these fatty acids generate their health effects. For more information see: Rokling-Andersen MH et al (2009) British Journal of Nutrition Vol 102: pg 995-1006; Kopecky J et al (2009) Proceedings of the Nutrition Society [Epub ahead of print]; Li JJ et al (2008) Molecular Nutrition & Food Research Vol 52: pg 631-45 and Krebs JD et al (2006) International Journal of Obesity (London) Vol 30: pg 1535-44.
Need a career change?
4
visit www.dieteticJOBS.co.uk NHDmag.com Dec '09/Jan '10 - issue 50
