Tuesday, April 5, 2011

Draft Australian Dietary Guidelines:

Are the 2010 Dietary Guidelines for Americans a preview of our own?

Every 5 years the US government is required by federal law to review and update its dietary guidelines, which then guides all federal food programs in the US. The new 2010 Dietary Guidelines for Americans were released a couple of months ago, and with Australia’s draft guidelines currently under review, and a draft expected for consultation in April/May we can’t help but wonder if America’s Dietary Guidelines are a preview of our own.

The message from the 2010 Dietary Guidelines for Americans with regards to grains is “whenever possible, replace refined grains with whole grains." The 2005 message to "make at least half your grains whole" still holds true, however, this time the guidelines are full of reminders to replace refined grains with wholegrains. For most Americans the recommendation for grain-based foods is 6 serves a day (one American serve is equivalent to 1 slice of bread or ½ cup of cooked rice or pasta), with at least 3 of those wholegrain. This amount is equivalent to the 48g Daily Target Intake for wholegrains, as recommended by Go Grains Health & Nutrition.

A series of swap this for that options are promoted in the new 2010 Dietary Guidelines for Americans such as swapping white rice with brown rice, white pasta with whole wheat, cornflakes with oatmeal and doughnuts with wholegrain bagels. The concept is similar to that of the Australian Governments’ current “Swap it, Don’t stop it” campaign, where by Australians are urged to swap some of the things they are doing now for healthier choices - http://www.swapit.gov.au/

The current Australian Dietary Guidelines do not recommend a quantitative amount for wholegrains, instead stating ‘Australians should eat plenty of cereals (including bread, rice, pasta and noodles) preferably wholegrain’. If the new Australian Dietary Guidelines follow the US, it is likely the food industry will develop and manufacture more food products with wholegrains to promote the additional health benefits of these foods. If the US is a preview of our market, wholegrain foods may become the norm. The growth in popularity of wholegrain foods has been demonstrated recently in the US, as The Wholegrains Council’s wholegrain stamp reports a 25% growth over the past 9 months, now appearing on over 5000 wholegrain products in over 22 countries.

The Australian Dietary Guidelines provide evidence-based nutrition information and advice for health professionals and consumers. The National Health & Medical Research Council (NHMRC) is leading the review of Australia’s guidelines together with the Department of Health and Ageing.

The Australian Dietary Guideline review process started in April 2008, with a group of nutrition experts – The Dietary Guidelines Working Committee meeting to establish the terms of reference and review the latest scientific research to make recommendations for updates to the guidelines. The first review process for the Australian Dietary Guidelines is expected to be commence in April/May this year, with the final guidelines planned to be released at the end of the year. We are waiting with anticipation that a quantitative recommendation for wholegrains is included in the draft 2011 Australian Dietary Guidelines. A quantitative recommendation encourages consistency in wholegrain public health messages in the media and on product packs, ultimately helping consumers understand the actual amount of wholegrains they need for good health.


We 'heart' legumes

Sound science supports legumes and cholesterol lowering for a healthier heart

There is consistent evidence from epidemiological studies showing that eating legumes can play a role in preventing some of our most serious chronic diseases, including cardiovascular disease, diabetes, as well as improving gut health and assisting with weight management. Despite this, Australians are not eating enough legumes. A consumption survey conducted by Go Grains Health & Nutrition in 2009 (which is currently in field again for 2011) found that not even a quarter of the 1700 Australians surveyed consumed legumes over the 2 day period food intake data was collected.

The research in support of legumes and health is not as extensive as that for cereal grains, mainly because there is generally a low intake of legumes in most free-living populations. Much of the legume research has focused on soy beans due to higher intakes of soy products such as tofu, soymilk, tempeh and textured soy protein; however, a meta-analysis just published has focused on non-soy legumes in relation to blood lipids. This is the second meta-analysis of this topic, is more vigorous in its methodology and includes four new studies since the 2002 review.

A total of 140 papers were retrieved from a search through MEDLINE, EMBASE and Cochrane databases through to July 2009. Ten randomised controlled trials were selected for analysis that compared a non-soy legume diet to a control diet. Each of the 10 studies lasted a minimum of 3 weeks duration, and reported blood lipid changes (in cholesterol, hypercholesterolemia or hypertriglyceridemia and/or cardiovascular disease) in intervention and control diets. The research included a total of 286 participants (70% males) from 5 countries with a mix of high, borderline high and normal baseline cholesterol levels.

The legume intake in the 10 studies ranged from 80-440g/day of peas, lentils, baked beans, pinto beans, lima beans or black eyed peas with a study length of 21 to 56 days. All studies reported net decreases in total cholesterol with a mean reduction of 11.76mg/dL (translating to around a 5% reduction). The combined results showed a significant decrease in unhealthy LDL cholesterol and triglycerides, however little effect on HDL cholesterol.

Although the number of participants was relatively small and majority were middle aged hypercholesterolemic men, the meta-analysis appears to be carried out very carefully. There was no publication bias or significant differences in the way the protocols were performed, and sensitivity analysis found no effect of study type, length or type of control on the results. The levels of legume intake in the studies are considerably above average legume consumption in Australia today, limiting the potential applicability in the findings, but also highlighting the potential health benefits if legume consumption can be increased amongst Australians, especially in those at higher risk of raised cholesterol and cardiovascular disease.

Non-soy legumes have a similar effect as soy-based supplementation on cholesterol lowering. The authors concluded this meta-analysis of randomised controlled trials provides the strongest evidence to date that non-soy legume consumption lowers serum total and LDL cholesterol and therefore may lower the risk of cardiovascular disease. This provides added weight to the body of scientific evidence supporting the role of legumes in the diets of Australians.

Bazzano et al 2011 Non-soy legume consumption lowers cholesterol levels: A meta-analysis of randomised controlled trials. Nutrition, Metabolism and Cardiovascular Disease (21) 94-103.