News with Dr Carrie Ruxton

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 pubIt has been suggested that regular lished which brings together evidence use of probiotics could help to reduce showing how probiotics may exert the requirement for antibiotics or some their actions. This includes modulating anti-inflammatory drugs. However, more immune function, impacting on how needs to be known about how differother microorganisms function and actent combinations of probiotics work ing on microbial products/food compotogether. nents within the gut. Different probiotics For more information see: Oelschlaecould have different functions dependger TA et al (2009) Int J Med Microbiol ing on their own metabolic properties. [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, cient characterisation of active ingrealpha-linolenic acid and beta glucan dients. Surprisingly, claims on probiotfibres (found in oats). The omega-3 fatty ics and soy isoflavones were rejected acids, DHA and EPA, were found to due to a lack of specific evidence on reduce blood pressure and triglycerides. cause and effect. To see the full list of

However, most of the proposed approved and rejected health claims health claims were rejected due to a visit: http://www.efsa.europa.eu/cs/ lack of appropriate evidence or insuffi 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 overblood pressure (by 2.6mmHg), serum weight and obese Germans (25-65 high-density lipoprotein and LDL ‘bad’ years) were given 150mg/day quercetin cholesterol. Although some markers of (a flavonoid found in apples and onions) CVD in this study remained unchanged, or a placebo for six weeks (with a fivequercetin may provide some protection week washout period between treatagainst CVD development. ments). For more information see: Egert S et al

Quercetin supplementation was (2009) British Journal of Nutrition Vol 102: associated with a reduction in systolic pg 1065-74.

Need a career change? 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.