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This conference takes place every 4 years and attracts some of the top nutritional scientists from around the world wishing to present their study findings or evidence based cutting edge views to the scientific community, public health sector, food industry, clinicians and students. I was fortunate to be able to attend this conference and present some of our study findings on the mediterranean diet with my colleague A/Prof Catherine Itsiopoulos from La Trobe University (see the end of the post).  

Plant omega 3 (alpha linolenic acid) just as important for health as fish omega 3 
(Session by Prof Penny Kris-Etherton)
Overall studies have found that plant omega 3 (ALA) is just as important, and in some studies even more important, than fish omega 3 (EPA, DHA) for preventing heart disease and strokes. This is good news for vegetarians who do not wish to take fish oil supplements. However, there appears to be increased health benefits if one also has plant omega 3 in addition to fish omega 3.  So vegetarians can get algal sources of fish omega 3 if they want the extra health benefits without eating fish but otherwise can stick with their plant sources.  It is recommended we have 2g of plant omega 3 daily which can be achieved with 2-3 teaspoons of chia seeds or 1 tsp flax seed oil or   1 tablespoon of ground flax seed or 1 tablespoon canola oil or 30g (handful) of walnuts or 40g pumpkin seeds or 1.5 tablespoons of soy bean oil. There was some concern that high dose plant omega 3 can increase the risk of prostate cancer but subsequent large studies have not found this to be the case, in fact, the reverse was found!  Plant omega 3 are converted to long chain type fish omega 3 EPA/DHA in the body but this conversion can be reduced by high intakes of omega 6 fats found in some polyunsaturated vegetable oils/margarine (such as safflower, grape seed, sunflower). If you consume a variety of oils (which includes monounsaturated oils like olive oil, peanut oil, sesame oil) then this should not be a problem.

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Monounsaturated fat and Extra virgin Olive oil
(Session by Prof Dariush Mozaffarian and Prof Perez Jimenez)
Photo: McDonalds in Spain serves their tuna/egg salad with extra virgin olive oil!

Monounsaturated fat also known as oleic acid can be found in both plant foods (e.g olive, canola, peanut, palm, sesame, soybean, nuts) and animal foods.  Carbohydrates in the diet can also be converted to oleic acid.  The research on the cardiovascular benefits of oleic acid has not been that favourable, however, most of the studies have been on animal sources of oleic acid. It is now believed that the health benefits of extra virgin olive oil (the purest less processed form of olive oil) have got nothing to do with its high oleic acid content but more to do with its phytochemical content.  The phytochemical phenolics found in olive oil are specific to olive oil and not found in any other food. The phenolic hydroxytyrosol  in extra virgin olive oil has not only been found to protect LDL cholesterol (the bad cholesterol) from oxidation (oxidation makes LDL cholesterol more atherogenic) but also has cardioprotective anti-inflammatory action  (by reducing NFKappa-6) and anti-clotting action (by reducing thromboxane B2). Hydroxytyrosol has also been shown to stimulate the production of glutathione in the body. Glutathione is made endogenously from amino acids and has potent antioxidant activity in the body. So it is now believed that olive oil is not high in antioxidants per se but is able to stimulate the production of antioxidants in the body which are health protective.  Also, during and after digestion, toxic peroxides develop and enter the blood stream along with the fats (post prandial lipaemia).  This short term physiological state post digestion is inflammatory and can promote clotting. The presence of extra virgin olive oil in the blood after digestion has been shown to reduce post meal inflammation by reducing thromboxane B2. Olive oil has also been shown to improve the integrity and function of the blood vessel walls (endothelium). Include 1-2 tablespoons of extra virgin olive oil in your diet and don’t be afraid that this will make you stack on the kilos as studies have not found that olive oil puts on weight….quite the reverse!  

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The Gut microbiome, prebiotics and their link to obesity, diabetes, fatty liver, bowel disorders, immunity and systemic inflammation
(Prof Raylene Reimer, Prof Nathalie Delzenne)
Photo:  Barcelona market sells an amazing variety of takeaway fresh fruit cups for a couple of euros!

The human gastrointestinal tract is host to a complex microbial ecosystem of hundreds of bacterial species also known as the gut microbiome. It plays a crucial role in the development of a healthy gut and immune system, while disturbances have been associated with systemic inflammation and in turn various disease states such as diabetes, fatty liver, cardiovascular disease, obesity, autoimmunity, joint pain and even depression. Keeping the gut microbiome stable against the dominance of pathogens or dysbiotic bacteria is emerging as a key factor in preventing many so called chronic diseases.  This represents a paradigm shift in our thinking of what causes many chronic diseases. Dietary prebiotics are food components that provide “food” for good bacteria, fermented by these bugs to produce beneficial metabolites. Prebiotics are primarily foods high in fibre (such as chia seeds, oat bran, psyllium husk, fruits, vegies, legumes, nuts), resistant starch (high in cold rice/pasta/potatoes) and fermentable sugars, also known as FODMAPs. FODMAPs include fructans/ inulin/oligofructose found in onions, garlic, wheat and as an additive in some packaged foods, galacto-oligosaccharides found in legumes and fructose and polyols found in many fruits and vegetables.  Following a low FODMAP diet in the short term helps reduce the symptoms of irritable bowel syndrome but may have adverse effects on bowel flora and overall health if followed long term. It is now believed that having an adequate intake of prebiotics may be just as important as probiotic foods (e.g yoghurt, kimchi, tempeh) and supplements for the maintenance of a healthy gut microbiome.  Fermentation of prebiotic foods (fibre/starch) produces short chain fatty acids such as acetataldehyde, priopionate, butyrate and lactate which have been shown to improve gut and liver function. These fatty acids also regulate gut peptides responsible for satiety (e.g GLP1, PYY, ghrelin) leading to reduced appetite and energy intake. Several studies have shown that increasing the intake of prebiotics can help with weight loss, especially abdominal fat loss. In contrast protein fermentation is considered more detrimental for human health as it results in the production of potentially toxic substances such as ammonia, amines, phenols and sulphides. This is another reason why eating too much protein and too little fibre/carbohydrates may not be good for you. Dysbiotic (pathogenic) bacteria release toxic substances, called lipopolysaccharides (LPS) which cross the gut barrier and enter the host blood, leading to stimulation of inflammatory pathways via interaction with receptors on macrophages and causing “systemic inflammation”.  This is turn can affect the function of many organs (e.g liver, brain, blood vessels), tissues (e.g joints) and physiological systems (e.g immunity). LPS migration is made easier by weaker gut barriers (or leaky permeable gut) but also by consumption of a high animal fat diet as LPS can follow the route of chylomicrons (globules of fat produced after digestion). Interestingly, HDL cholesterol can help clear LPS from the body.  Clear associations exist between glucose intolerance/diabetes/fatty liver/obesity and endotoxaemia (stimulated by the actions of LPS).  Good bacteria (stimulated by prebiotics) can ameliorate these effects by improving gut barrier function by up-regulating tight junction proteins which helps to repel LPS and by promoting cell differentiation in the gut leading to an increase in L-cells which release GLP1 and GLP2. These hormones are responsible for satiety, glucose metabolism, gut cell proliferation and barrier function and control of liver lipids levels. Animal and human studies have shown that increasing the intake of prebiotcs results in beneficial changes in gut peptides, reductions in appetite and energy intake and improvements in body composition and hepatic fat levels.  It would appear that eating a more plant based diet high in legumes (like the traditional Mediterranean diet) would encourage a healthy gut microbiome and all the health benefits associated with such diets.

4 simple lifestyle factors that can significantly reduce your risk of heart disease, cancer and diabetes (from the EPIC study)
(Session by Prof Heiner Boeing)
a) keep your body mass index below 30 
b) do not smoke
c) exercise (e.g walking) for 3.5 hours per week
4) eat more plant foods (fruit/veggies/wholegrains/legumes) and less red meat              
      
Best way to lose weight and keep it off
(Session by Prof Arne Astrup)
We have been lead to believe that slow weight loss is the best way to lose weight and to keep it off. There is now overwhelming evidence that the reverse is true. Greater initial weight loss has been associated with greater long term outcome.  In studies where patients were put on more strict diets of about 800 calories lost more weight faster and were able to keep it off longer than patients who were placed on slower weight loss higher calorie diets.  The 800 calories ideally should come from more protein and less  carbs  because protein increases satiety by altering several gut hormones (increased GLP1 and CCK and reduced Ghrelin). Carbohydrates are still needed because they are best at stopping hunger but protein increases the feelings of fullness.  So it is not recommended to completely eliminate carbs when trying to lose weight but to have a protein carb ratio of 1:2. For example most people need to have about 60-100g protein per day (depending on their weight) so the recommended carb amount would be around 120-160g per day when trying to lose weight. And yes, the carbs consumed should be unprocessed low GI grainy types not fluffly white bread or donuts because the former are more satisfying, reduce hunger and maintain more even blood sugar and insulin levels which favours the biochemistry that breaks down fat rather than the storage of fat. Studies have also shown that most people are already consuming enough (or too much) protein but are eating too much poor quality high GI processed carbs.  So simply reducing the intake of such poor quality carbs should result in weight loss and maintenance of the weight lost. Ideally, some of our protein should come from plant sources such as tofu, nuts and pulses (i.e lentils, baked beans, chickpeas), which also provide fibre (for satiety) and low GI carbs … perfect!  In fact, high animal protein diets can adversely affect the gut bacteria promoting dysbiosis (bad bugs!) and inflammation whereas the reverse is true for plant proteins (see above). And what about the 5:2 diet or intermittent fasting diet i.e 5 days normal eating and 2 days (non-consecutive) of 500-600 calories? There is evidence that it works in the short term but more studies are needed on its long term effects. 
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The mediterranean diet, home gardens and health
(A/Prof Catherine Itsiopoulos, A/Prof Antigone Kouris, Ms Tania Thodis)
Photo:  Amazing variety of fresh fruits, vegetables and spices sold at Barcelona Market

Preliminary findings from our research at La Trobe University and Tania Thodis' PhD suggests that elderly Greek Australians that have a home garden may have a health advantage (such as lower blood pressure). This could be due to the consumption of more nutrient/ phytochemically dense vegetables and fruits grown at home compared to supermarket produce (we hope to do some testing here). Also, having an extensive home garden facilitated adherence to a more traditional Greek mediterranean diet. Previous studies conducted by A/Prof Itsiopoulos and myself have shown that adherence to such a diet reduces overall mortality, reduces blood sugar levels and can increase blood levels of antioxidant carotenoids (linked to lower rates of heart disease, cancer and diabetes complications). I will keep you posted on new findings as they emerge. 

 
 
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A revised set of dietary guidelines for Australians was recently released by the National Health and Medical Research Council. For the first time in 30 years since the inception of dietary guidelines Australians are no longer advised to reduce their intake of total fat.  There have been a series of well controlled studies in the last 10 years reporting that a high fat intake does not increase the risk of heart disease, stroke, cancer or even obesity! In fact, the high fat 'traditional' mediterranean diet has been linked to lower rates of heart disease, diabetes, cancer and obesity!   However, mechanistic studies have found that the TYPE of fat is important for the prevention of these diseases. This explains why the revised guidelines focus on replacing saturated fat with mono and polyunsaturated fat and they specifically state:  
1) Limit intake of foods high in saturated fat such as many biscuits, cakes, pastries, pies, processed meats, commercial burgers, pizza, fried foods, potato chips, crisps and other savoury snacks.2)  Replace high fat foods which contain predominantly saturated fats such as butter, cream, cooking margarine, coconut and palm oil with foods which contain predominantly polyunsaturated and monounsaturated fats such as oils, spreads, nut butters/pastes and avocado. 
There is controversy surrounding the consumption of natural oils high in saturated fats (extra virgin coconut oil, coconut milk, red palm oil high in carotenoids/tocotrienols) or omega 6 fats (sunflower/safflower oil). Some studies suggest that the former are not detrimental but the latter may be detrimental if consumed in large amounts.
As the evidence emerges I will review them in my posts. In the mean time, enjoy eating a wide variety of extra virgin oils (added mainly to vegetables/fish etc to make more palatable) and avoid commercial foods high in animal fats or hydrogenated vegetable fats.  

 
 
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Recent studies have linked calcium supplements with an increased risk of having a heart attack or stroke in older women. Taking vitamin D at the same time does not appear to reduce the risk.
Participants in these studies were mainly taking calcium carbonate (i.e chalk!) and calcium citrate supplements. The calcium in these supplements is not well absorbed and is usually not accompanied by other nutrients important for bone health, like magnesium, boron, vitamin K, silica. Calcium hydroxyapatite (or ground bone) may be better absorbed than calcium carbonate/citrate.
Supplements that contain calcium hydroxyapatite usually also have the desirable amount of magnesium in a 2:1 ratio (calcium:magnesium). Magnesium is important for the correct utilisation of calcium in the body. If you need to take a calcium supplement because your diet is very low in calcium (a dietitian will help you work this out) and have osteoporosis or osteopenia then it may be safer to take a supplement which does not contain calcium carbonate/citrate. Avoid taking more than 600mg of calcium per dose as your body cannot absorb more than this and avoid taking more than 600mg supplemental calcium per day. Also prefer taking your calcium supplement at night as it is better absorbed. If you have heart disease or are at high risk of heart disease/stroke then you may want to avoid all calcium supplements and prefer calcium from food. Other medical experts have commented that the data from this study are inconclusive about whether calcium supplements are unsafe. http://www.medicalobserver.com.au/news/radical-call-to-stop-calcium-supplements
Before commencing any supplements best to check with your doctor and dietitian.

 

    About this blog

    The purpose of this blog is to keep my patients, students and followers up-to-date with the latest in nutrition research, food products and nutriceuticals.

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    I have over 25 years experience in nutrition as an academic, researcher, clinical dietitian, co-author of 5 university text books, author of 3 of my own books and editor of a medical nutrition journal. My patients challenged me to develop a healthy gourmet biscuit so now I also have experience in developing and marketing my own food product! I am currently an Adjunct
    Asscoiate Professor in Dietetics at La Trobe University and run a busy private practice in Melbourne

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