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Food Processing and Health


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How the way food is processed and cook can alters its health affects on us.

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Food Processing and Health

  1. 1. Food Processing and Health “It’s not just what you eat, but how you cook it too” Associate Professor Tim Crowe School of Exercise and Nutrition Sciences Deakin University @CroweTim Nutrition @ DEAKIN 1 1
  2. 2. Topics to be Covered 1. Inflammation: what is it and when can it be bad for us? 2. Update on trans fats 3. Effect of heating on cooking oil 4. Advanced glycation end-products (AGEs) 5. Acrylamide production in baking 6. Charring of food producing HCAs and PAHs 7. Practice implications Nutrition @ DEAKIN 2
  3. 3. What is Inflammation? • Body's normal response to protect against infection, injury, or disease • Involves activation of monocytes, neutrophils, and lymphocytes and the release of inflammatory mediators • Without inflammation, wounds and infections would never heal • Acute inflammation: Initial response to harmful stimuli and involves ↑movement of leukocytes to the injured tissues • Chronic inflammation: Leads to a progressive shift in the type of leukocyte cells present at site of inflammation, particularly the presence of macrophages • Macrophages: secrete coagulation factors, reactive O2 species, cytokines, growth factors, nitric oxide and also induce continued recruitment of monocytes from circulation Nutrition @ DEAKIN 3
  4. 4. The Inflammatory Process Source: Nutrition @ DEAKIN 4
  5. 5. Chronic Inflammation and Disease • Impairs endothelial function and vascular lining • Increases platelet activation and clotting • Depletes intrinsic antioxidants • Generates free radicals and amplifies oxidative stress • Delays wound healing and tissue regeneration • Promotes cell aging and premature cell death • Suppresses or amplifies immune responses Nutrition @ DEAKIN 5
  6. 6. Causes of Chronic Inflammation Unlike acute inflammation showing redness, swelling and pain, chronic inflammation can be invisible Causes • Autoimmune diseases e.g. such as rheumatoid arthritis, lupus • Infectious agents e.g. H. pylori, viruses • Atherosclerosis • Environmental e.g. smoking • Allergens • Central adiposity: more macrophages localised in fat will thus produce more inflammatory mediators Nutrition @ DEAKIN 6
  7. 7. Treating Inflammation •Exercise: Negative association between PA and CRP •Weight loss: ↓ body fat means reducing the ‘inflammatory factories’ being the fat cells •↑fruit, vegetables, fish, olive oil •↑fibre (inversely associated with CRP) •↓ trans and saturated fats •Moderate alcohol •Quitting smoking Nutrition @ DEAKIN 7
  8. 8. Trans Fats • Unsaturated fat that behaves like a saturated fat because of its chemical structure • Occurs in nature (e.g. CLA in dairy), but in small amounts. Most come from hydrogenation • Intermediate melting temp and shelf stability makes them desirable (texture and mouthfeel) for use in food industry • Recommended to be <1% of EI Nutrition @ DEAKIN 8
  9. 9. Trans Fats Hydrogen + Vegetable Oil = Partially Hydrogenated Vegetable Oil (“PHVO”) Up to 6 different trans fats produced in this process • • Straight molecules (trans fat) can pack more closely against one another (like saturated fat), making the substance more solid and stable Adding hydrogen also prevents the oil from becoming rancid as quickly Nutrition @ DEAKIN 9
  10. 10. Trans Fats and CVD • ↑ LDL, VLDL, TG and ↓HDL and LDL particle size • ↑ inflammation via CRP, TNF-α and IL-6 • Inhibition of FA incorporation into cell membranes (affecting fluidity and signalling) • Interfere with elongation and saturation of FAs • Linked with IR, visceral adiposity and development of T2DM • 2%↑ in EI from trans fats = 23%↑ in CVD risk Nutrition @ DEAKIN 10
  11. 11. Trans Fats and CVD Mozaffarian D et al. Trans fatty acids and cardiovascular disease N Engl J Med 2006;354:1610-1613 Nutrition @ DEAKIN 11
  12. 12. Regulation of Trans Fats: International • Denmark (2003) and Switzerland (2008) banned the sale of foods in which trans fat is more than 2% of total fat content • US (2008) requires listing of trans fats on label (<0.5 g can be labelled as ‘trans free’) • New York and Philadelphia banned restaurant/fastfood sales of foods with >0.5 g trans fat per serve Nutrition @ DEAKIN 12
  13. 13. Regulation of Trans Fats: Australia • FSANZ not in favour of requiring trans fats to be labelled as believes will • • • • have a small effect on consumption FSANZ dietary modelling estimates intake at 0.5% of EI with 90% of Australians having trans fat intake <1% EI/day* (WHO recommends trans fats contribute < 1% of daily EI) Around 60% to 75% of TFA intake is derived from ruminant foods FSANZ (2009) reviewed the outcome of non-regulatory measures to reduce TFAs in the food supply and found intakes of TFAs from manufactured sources ↓ by around 25 to 45 percent since 2007* For Australians with total TFA intake >1% of EI: pastry products, sausages and luncheon meats, and creamy style pasta dishes contributed disproportionally to high TFA intakes * Intakes of Trans Fatty Acids in New Zealand and Australia. Review Report – 2009 Nutrition @ DEAKIN 13
  14. 14. Trans Fat Intake: Aus vs US • Australia: 0.5% of EI as TFA (majority from ruminant sources) • US: 2.6% of EI as TFA (80% from PHVO and 20% from ruminant sources) Nutrition @ DEAKIN 14
  15. 15. Reducing Trans Fats in the Diet • Read labels: the amount of trans fat in a food must be declared if a nutrition claim is made about cholesterol, saturated or unsaturated fat, or trans fatty acids • Choose margarines that have <1% trans fatty acids • Reducing intake of the ‘usual culprits’ • HF tick foods (<0.2% TFA of fat for all products except margarines and vegetable oils which must limit trans fat to <1% of total fat) Nutrition @ DEAKIN 15
  16. 16. Behaviour of Oil during Cooking • Prolonged oil use causes polymerisation reactions, which cause foaming and ↑ viscosity, ↓quality of foods, and ↑susceptibility of oil to oxidation • Various compounds produced from oil during frying: • Aldehydes and ketones • Hydrocarbons • Lactones and alcohols • Oxidised sterols • Peroxidised fatty acids • Free radicals • Health effects unlikely except for when using near-rancid oil and/or high consumption Nutrition @ DEAKIN 16
  17. 17. Smoke Point • Temperature at which a cooking fat or oil begins to break down and give off smoke • At this point, deterioration of flavour and nutritional quality begins and the oil is more prone to bursting into flame (i.e. its flash point) • Not only is the smoke dangerous, but the materials that remain in the liquid start to affect the flavour of the food being cooked Nutrition @ DEAKIN 17
  18. 18. Smoke Point •Smoke point determines what the oil can be used for, dictating the maximum useable temperature of the oil •A high smoke point is ideal for deep-fat frying •Oil which has oxidised because of exposure to air, heat and light will have a lower smoke point •Using oil repeatedly will also make it smoke sooner from ↓ smoke point Nutrition @ DEAKIN 18
  19. 19. Smoke Point of Oils Olive Oil (Extra Virgin) 191°C Olive Oil (Virgin) 199°C Canola 204°C Olive Oil, high quality (Extra Virgin) 207°C Almond Oil 216°C Grapeseed Oil 216°C Coconut Oil 232°C Peanut Oil 232°C Sunflower Oil 232°C Palm Oil 235°C Soybean Oil 238°C Olive Oil (Extra Light) 242°C Canola Oil (high oleic acid) 246°C Safflower Oil 266°C Nutrition @ DEAKIN 19
  20. 20. Antioxidants and Oil Stability • PUFA content a major determinant of oxidation susceptibility Canola as an Example • Canola oil ± vitamins C and E used for deep-fat frying potatoes once per day for 10 days or once per week for 10 weeks* • Smoke point ↓ over 10 fryings (17% in control and 9% in antioxidant supplemented) • Canola oil without antioxidants found to safe to use 8 times on a daily basis, or 7 times on a once-weekly basis • Canola oil with antioxidants, smoke point did not decrease below 170°C in both daily and weekly fryings and safe to use at least 10 times for both frying intervals * Önal B and Ergin G. Antioxidative effects of a-tocopherol and ascorbyl palmitate on thermal oxidation of canola oil. Nahrung 2002;46:420-426 Nutrition @ DEAKIN 20
  21. 21. Choice Recommends Choosing the right cooking oil - August 2010 All-purpose oils • Grapeseed • Sunflower Oils for stir-fry cooking • Peanut • Macadamia Oils for low heat cooking and salad dressings • Olive Nutrition @ DEAKIN 21
  22. 22. Advanced Glycation End-Products (AGEs) • Arise exogenously by heating food, or endogenously through normal metabolism and aging • Formed from non-enzymatic reaction of reducing sugars with free amino groups of proteins, lipids, and nucleic acids (Maillard reaction – leads to browning) • Oxidative stress due to hyperglycaemia can ↑ AGE formation • Pathological effects of AGEs related to ability to promote oxidative stress and inflammation • ↑ vascular permeability, inhibition of vascular dilation, and oxidised LDL linked to causative role in the vascular complications of diabetes Nutrition @ DEAKIN 22
  23. 23. NFκB: Nuclear factor kappa B – regulates inflammatory genes RAGE: Receptor for advanced glycation end products ROS: Reactive oxygen species Source: Nutrition @ DEAKIN 23
  24. 24. Diet and AGEs • Heating (grilling, frying, roasting) has a significant accelerating effect in generation of AGEs in food processing • ∼10% of ingested AGEs is absorbed with food • Animals studies show relationship between high dietary AGE intake and oxidative stress, IR, T2DM and development of complications (vascular and renal) • Restriction of dietary AGEs in animals associated with a significant ↓ in circulating levels of vascular disease markers (e.g., adhesion molecules) as well as of inflammatory mediators Nutrition @ DEAKIN 24
  25. 25. AGE Content of Foods • Beef, poultry, fish and eggs high in AGEs when cooked in a similar way • High-fat cheese can be a significant source (from pasteurisation and long holding times at room temp) as too snack foods (chips, biscuits) • Short heating time, low temperature, high moisture, and preexposure to acidified environment can limit AGE formation • Grains, legumes, breads, F&V, and milk lowest sources unless prepared with added fat Detailed listed of AGE content of foods Uribarri J et al. J Am Diet Assoc 2010;110:911-916 Nutrition @ DEAKIN 25
  26. 26. AGEs and Cooking Methods Marinated in Vinegar Marinated in Lemon Juice 1 = Raw beef 2 = Roasted beef with no vinegar/lemon 3 = Roasted beef after marinating with vinegar/lemon for 1 hour Beef (25 g) roasted for 15 minutes at 150°C with or without pre-marinating in 10 mL vinegar (A) or lemon juice (B) for 1 hour *Significant changes compared to the raw state (P<0.05) #Significant changes compared to cooked without marinating samples. Uribarri J et al. J Am Diet Assoc 2010;110:911-916 Nutrition @ DEAKIN 26
  27. 27. Low AGE Diet • 36 subjects (18 healthy and 18 T2DM) randomised to ‘normal’ diet or isocaloric low-AGE diet (↓50%; boil, stew, steam food instead of frying, baking, grilling) for 4 months* • No significant changes in metabolic markers on ‘normal’ diet for healthy controls or T2DM (apart from effects normal for an ongoing high AGE diet) On low AGE diet for T2DM patients: – Insulin, HOMA, leptin, TNF-α, NF-κB, and serum AGEs all ↓ – ↑ AGER1 (AGE receptor; negative regulator of AGE action), SIRT1 (modulator of insulin action) and adiponectin (↑ insulin sensitivity) On low AGE diet for healthy controls: – ↓ seen only in serum AGEs and isoprostanes (inflammatory eicosanoid-like substances) *Uribarri J et al. Diabetes Care 2011;34:1610-1616 Nutrition @ DEAKIN 27
  28. 28. Acrylamide • Found in plant-based baked starchy foods (potato chips, biscuits, breakfast cereals, toasted bread, coffee) • Not typically found in meat, dairy or seafood • Arises from reaction b/w reducing sugars and AAs at high temp (Maillard reaction) - not found in food prepared below 120°C • Debate over current exposure levels being of significance c.f. cancer effects seen in animals (typically 300 to 1000-times greater exposure dose) though concern expressed for highintake consumers* • Few observational studies link it to ↑ cancer risk, with most showing a negative finding * Nutrition @ DEAKIN 28
  29. 29. Acrylamide • International Agency for Research on Cancer (IARC) classifies acrylamide as "probably carcinogenic to humans" on basis of evidence from animal studies • Food exposure levels higher than that expected to occur as a result of contact between food and food packaging or use of cosmetics Spivey A. Environ Health Perspect 2010;118:A160–A167 Nutrition @ DEAKIN 29
  30. 30. Ways to Decrease Acrylamide • ↓cooking time, blanching potatoes before frying, and postdrying (drying in a hot air oven after frying) can ↓acrylamide content of some foods • Soaking raw potato slices in water for 15-30 minutes before frying or roasting helps ↓ acrylamide formation during cooking • Cooking potato chips to a light golden colour and using maximum temperatures of 175°C when deep-frying and 230°C when baking • Toast to lightest acceptable colour Nutrition @ DEAKIN 30
  31. 31. Red Meat and Colorectal Cancer • ↑ risk estimates in the range of 20 to 50% for highest vs lowest intakes of red meat in prospective studies • World Cancer Research Fund 2007 report* rates the evidence as ‘Convincing’ • Not clear whether it’s the intake of red meat (?excess haem Fe), form of meat (esp. processed), high fat diets, formation of nitrosamines, or the way meat is cooked • Cooking (charring) of meat produces two types of carcinogens – Polycyclic aromatic hydrocarbons (PAHs) – Heterocyclic amines (HCAs) *The Second Expert Report, Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective Nutrition @ DEAKIN 31
  32. 32. HCAs and PAHs • Heterocyclic amines (HCAs): formed at high temps (and long cooking times) from reaction of creatine or creatinine, AAs, and sugar • Found in fried, grilled and BBQ meat, poultry and fish • Potent mammary, lung, colon, stomach and prostate mutagens in animal models (at very high doses of HCAs though) • Polycyclic aromatic hydrocarbons (PAHs): produced from incomplete combustion of organic compounds • Formed in cooking and smoking of meat • Flames from grilling over fire contain PAHs that can adhere to the surface of meat Nutrition @ DEAKIN 32
  33. 33. Recent Evidence for Charring 1. Case control: 50% ↑prostate cancer risk with ≥1 serve/wk of grilled or well-done meat John EM et al. Nutr Cancer 2011;63:525-537 2. Case control: >3 serves/wk charred meat doubled risk of 3. 4. hyperplastic polyps Burnett-Hartman AN et al. Nutr Cancer 2011;63:583-592 EPIC study: HCA intake associated with 1.47 RR (1.131.93; P=0.002) for colorectal adenoma for highest vs lowest quartiles of intake Rohrmann S et al. Am J Clin Nutr 2009;89:1418-1424 EPIC study also showed ↑ adenoma risk with consumption of extremely browned meat Nutrition @ DEAKIN 33
  34. 34. Reducing HCA and PAH Exposure • Avoid direct exposure of meat to an open flame or a hot metal surface and avoid prolonged cooking times (especially at high temperatures) • Marinating can reduce HCA formation by 90% • Remove any blackened areas before eating • Clean grill well between uses (scrub off blackened parts) • Continuously turning meat over on a high heat source can substantially ↓ HCA formation Nutrition @ DEAKIN 34
  35. 35. Putting it into Practice •Diet high in F&V, grains, and quality healthy oils •Low in processed foods especially deep-fried take-away, and baked CHO foods •Combined with choosing lower-temperature cooking methods will decrease trans fats, AGEs, HCAs, PAH, and acrylamide intake Nutrition @ DEAKIN 35