Draft Australian Dietary Guidelines (PDF, 3MB) - Eat For Health

2.2.5.1 Cardiovascular disease, type 2 diabetes and excess weightmechanismsFood components with anti-oxidant activity including vitamins (vitamin C and E) andphytochemicals in these foods may reduce the risk of inflammation and haemostasis, and ofcholesterol becoming oxidised and deposited in blood vessels to form the atherogenous plaquesthat underlie many cardiovascular conditions [180, 204-206]. Several studies have shown thatconsumption of vitamin C is associated with reduced risk of cardiovascular disease and stroke,however, other studies have shown no protective effect [207] [9]. Vegetables and fruit are low insodium and saturated fat [10]. Plant foods including vegetables and fruit provide potassium andmagnesium, both of which have been linked to lower blood pressure [9]. Importantly, reviews ofthe effect of beta-carotene on coronary heart disease suggest that benefits may be related to thecomponents of the foods, various antioxidants and micronutrients in these foods or otherconfounding factors, rather than to the beta-carotene alone [208].Most fruit, vegetables and legumes have a low energy (kilojoule) density and high dietary fibre andwater content, providing a plausible mechanism for the association of consumption of these foodswith reduced risk of weight gain. Any effect is likely to be mediated through potentially increasingsatiety, and also through taking longer to chew, which leads to reducing total energy (kilojoule)intake [9, 10]. High dietary fibre intakes have been linked to lower rates of obesity, type 2 diabetesand cardiovascular disease, mainly through an effect on plasma cholesterol [9]. The majority ofvegetables are nutrient-dense and low in kilojoules - in particular, green, Brassica and other ‘salad’vegetables are relatively low in energy (kilojoules) [10]. However, starchy vegetables are lessnutrient-dense and are higher in kilojoules, but provide a rich source of complex carbohydrates[10].Diets high in fibre and specific complex carbohydrates such as non-starch polysaccharides havebeen used with modest success by people with type 2 diabetes attempting to lose weight. Thesmall effects seen in these experimental situations might relate to a satiating effect due to theprolongation of food absorption and a smoothing of the blood glucose response after meals [9].In the prevention and dietary control of type 2 diabetes, some vegetables are likely to be ofparticular value because of their low energy density and relatively high content of dietary fibre,although longer term studies may be required to demonstrate effects.Legumes are also believed to confer cardiovascular health benefits because they provide a valuablelow saturated fat source of protein as an alternative to meats, and because of their glycaemicproperties and phytoestrogen and isoflavone content [209, 210]. These reviews suggest theisoflavone in soy foods may have a role in cholesterol reduction, improved vascular health,preservation of bone-mineral density [209] and anti-oestrogenic, anti-proliferative, pro-apoptotic,anti-oxidative and anti-inflammatory processes [210]. However more research is needed todetermine the relative effect of legumes/beans and soy foods themselves as opposed to isoflavonesspecifically.DRAFT Australian Dietary Guidelines- December 2011 40