QUANTITY VERSUS QUALITY OF FAT IN THE DIET. Marius Smuts

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1 QUANTITY VERSUS QUALITY OF FAT IN THE DIET Marius Smuts Centre of Excellence in Nutrition

2 CONTENT Background on fatty acids Roles of Essential fats Quantity of fat in the diet Quality of fat in the diet Summary Conclusions

3 HISTORY OF FATTY ACID RESEARCH challenging and interesting research field spans over 80 yrs 1929 specific components of fat essential for proper growth in animals 1960 s clinical signs of EFA deficiency became apparent in humans 1970 s EFAs are dietary precursors of eicosanoids and there structural role in membranes 1980 s the role of EFA metabolites confirmed in growth and development 1990's - the structural and functional properties of LC- PUFAs increasingly recognized last decade role of individual fatty acids

4 ESSENTIAL FATS : EFAs Omega-3 Family Pathway Omega-6 Family Pathway ALA PARENTS LA Must be supplied by the diet Balance the amount!

5 ESSENTIAL FATS : EFAs Omega-3 Family Pathway Omega-6 Family Pathway ALA PARENTS LA Body converts EPA AA Body converts Anti-inflammatory substances Pro-inflammatory substances

6 ESSENTIAL FATS : EFAs Omega-3 Family Pathway Omega-6 Family Pathway ALA PARENTS LA Body converts EPA AA Body converts DHA DPA

7 ESSENTIAL FATS : EFAs Omega-3 Family Pathway Omega-6 Family Pathway ALA PARENTS LA Body converts EPA AA Supplied by: -marine sources -eggs -etc. Body converts DHA DPA

8 ESSENTIAL FATS : EFAs Omega-3 Family Pathway Omega-6 Family Pathway ALA PARENTS LA Body converts EPA AA Body converts Most abundant fat in the brain DHA DPA

9 PHOSPHOLIPID BILAYER

10 LCPUFA METABOLITES AND THEIR FUNCTIONS Substrate (fatty caids) Metabolite (eicosanoids) Function Arachidonic acid (C20:4n-6) Eicosapentaenoic acid (C20:5n-3) Dihomo-gammalinolenic acid (C20:3n-6) TXA2 PGI2 LTB4 PGE2 TXA3 PGI3 LTB5 PGE1 Potent platelet coagulant Anti-platelet aggregator+vasodilator Chemotactic agent Pro-inflammatory Less potent platelet coagulant Anti-aggregation + vasodilator Less potent chemotactic agent Anti-inflammatory + anticoagulant

12 Health and Disease States - LCPUFAs can play a role - Cardiovascular disease Growth and development - maternal nutrition and pregnancy - infant nutrition (child nutrition) Cancer Inflammation Immune system Rheumatoid arthritis Skin diseases (atopic eczema) Alcoholism Diabetes Hypertension & stroke Depression and aggression Dyslexia, schizophrenia, hyperactivity, Ca-met., etc.

13 INTRODUCTION Too little or too much fat in the diet could be detrimental to health. Not enough essential fatty acids in the diet, i.e. those that cannot be made by the body, can lead to deficiencies. In contrast too much fat, but especially the wrong type of fat in the diet, can contribute to the development of noncommunicable diseases.

14 NEW EVIDENCE Health consequences of dietary fat go beyond the role as energy sources Fats and FAs should be seen as key nutrients affecting: - early growth and development - nutrition-related chronic diseases later More emphasize how to improve the quality or type of fat as the most important factor for wellbeing

15 NEW EVIDENCE..cont More convincing evidence regarding: - role of EFAs during pregnancy & lactation - role of LC-PUFAs as structural components for dev. of brain & CNS All making the process for defining requirements and recommendations more complex Need arises focus more on role of individual FAs Paradigm shift on how we look at or define fats & FAs or oils.

16 NEW EVIDENCE..cont SFA, MUFA & PUFA or even EFAs, LC-PUFAs, n- 6, n-3, etc too simplistic and too non-specific FAs under the same grouping have sometimes quite different properties Actual FAs & their amounts sometimes much better (n-6/n-3 ratio) [Restrict trans fat intake to <1%E]

17 QUANTITY OF FAT IN THE DIET Cross-sectional studies supported the hypothesis that higher total fat is associated with higher body weight Several reports in the past concluded that excessive dietary total fat consumption increases the risk for obesity, CHD and certain type of cancers Recently carefully performed prospective observation studies do not necessarily support the same sentiment It is well-known that despite decreased intakes of total dietary fat, obesity rates increased

18 QUANTITY OF FAT IN THE DIET Both the Framingham studies and the British National Diet and Nutrition Survey showed that irrespective of decreased energy from fat, the prevalence of obesity increased Other studies showed that %E from fat is inversely related to weight change in women but positively associated in men without any morbidity Swedish study in women (6 yr follow-up) total energy and total fat was only associated with increased weight in a sub-population defined as "predisposed"

19 QUANTITY OF FAT IN THE DIET Other studies like the Nurses' Health Study found a weak association but no clear association with those "predisposed" to obesity Overall, the data from prospective cohort studies are inconclusive on the relationship between total fat intake and body weight RCTs (industrialised countries) study showed that isocaloric diets with different levels of total fat, response to a diet with high %E from fat (40 %E) did not differ from a diet with low %E from total fat (20%E)

20 Diet composition and weight loss Randomly selected group of overweight and obese men and women (n= 811) Randomized clinical trial Two years intervention Regular follow-up Different diets Fat Prot. CHO %E %E %E Low-fat, average protein Low-fat, high protein High-fat, average protein High-fat, high protein Sacks et al., 2009

21 Effect of low- and high fat diets on weight loss and risk factors for cardiovascular disease In overweight and obese participants there were no differences between the effect of low vs high fat diets on weight loss achieved over two yeas. Regular follow-up during the two years played an important role in weight loss. All the diets reduced risk factors for cardiovascular disease. The two low-fat diets (20%E) decrease LDL-C more than did the high-fat diets. The lowest carbohydrate diet (35%E) increased HDL-C levels more than the highest carbohydrate diet (65%E) All the diets except the highest carbohydrate diet (65%E) decreased triacylglycerol levels. Sacks et al., 2009

22 QUANTITY OF FAT IN THE DIET Conversely, response on high %E from fat diets can even lead to greater weight loss than observed in lower fat diets (?dyslipidemias) A few meta-analysis of RCT reported mixed results Nordmann et al. (2006) reported that a low CHO with no energy restriction on protein and total fat to be as effective as a low fat higher CHO, energy-restricted diets in inducing weight loss for up to 1 yr (low fat diets associated with: lower TC & LDL-C, but lower HDL-C & higher TAG levels)

23 QUANTITY OF FAT IN THE DIET Systematic review and meta-analysis of 33 RCTs (n=73 589) and 10 cohort studies in developed countries lower fat leads to a small but significant and sustained reduction in body weight in adults (Hooper et al., 2012) Interpretations difficult based on low fat diets as they are characterised by energy restriction

24 QUALITY OF FAT IN THE DIET SFAs (animal, palm kernel & coconut): Integral part of the human diet, present in all fats and oils in different quantities Although SFAs associated with higher LDL-C concentrations, Mensink et al. (2003) concluded, because it raise HDL-C & decrease TAG, it resulted in little net effect of TC:HDL-C ratio compared to CHOs Recent meta-analysis of prospective epidemiologic studies, the authors concluded there is no significant evidence that SFAs are associated with an increased risk for CHD

25 QUALITY OF FAT IN THE DIET It was convincingly shown that by replacing SFAs with PUFAs the risk of CHD was lowered in both prospective cohort studies & RCTs Certain individual SFAs, like palmitic acid (C16:0) have more cholesterol-raising properties than lauric acid (C12:0) On the other hand, stearic acid (C18:0) has shown some favourable effects on blood lipid profiles

26 QUALITY OF FAT IN THE DIET MUFAs: potential benefits shown in the past are now contradict by the latest studies that fail to show the some notion, with some showing even higher risks of CVD (Nurses' Health Study) PUFAs: quality of fat is mainly determined by the proportion of specific PUFAs it contains of BOTH the omega-6 & omega-3 series EFAs play an important role in well-being, dietary EPA & DHA consumption has been demonstrated to have various physiological benefits on BP, HR, TAG levels, inflammation and endothelial function

27 QUALITY OF FAT IN THE DIET Consistent evidence of reduced risk of fatal CHD & sudden death when consuming approximately 250 mg/d of EPA + DHA has been shown (Smit et al., 2009) Chowdbury et al. (2014) in a systematic review and meta-analysis concluded that this study does not yield clearly supportive evidence to encourage high consumption of PUFAs and low SFAs The Risk and Prevention Study Group (Italy) found no significant benefit of omega-3 fatty acids in reducing the risk of death from cardiovascular causes or hospital admission for cardiovascular causes (NEJM, 2013)

28 QUALITY OF FAT IN THE DIET TFAs: affects several cardiovascular risk factors & contribute significantly to an increased risk of CHD events

29 Health implications of high fat intake on risk factors for coronary heart disease Type of Fat TC LDL-C ( bad ) HDL-C ( good ) Trans fatty acids SFAs MUFA (vs SFA) - PUFA TC = total cholesterol; LDL-C = low density lipoprotein cholesterol; HDL-C = high density lipoprotein cholesterol; SFA = saturated fatty acids; MUFA = monounsaturated fatty acids; PUFA = polyunsaturated fatty acids

30 Summary of the effect of dietary fat on CHD Type of fat Fatal CHD CHD events TFAs - Convincing increased risk PUFA for SFA Convincing decreased risk Convincing decreased risk N-3 LC-PUFA - Convincing decreased risk Total fat Convincing no relationship Convincing no relationship Adapted from Skeaff & Muller, 2009

31 EPA and DHA content and requirements of different fish species Type of fish Amount (g) of EPA + DHA per 100 g portion Number of times per week a 90 g portion should be consumed to provide about 500 mg EPA+DHA per day Amount of fish (g) required per day to provide 500 mg EPA+DHA Mackerel (salted) Salmon, Atlantic Herring, Atlantic Bluefin tuna Pilchards Snoek Sardines Rainbow trout Hake Tuna, light Smuts & Wolmarans, 2013

32 EFFECTS OF A FISH FLOUR- ENRICHED SPREAD ON COGNITION AND ABSENTEEISM IN SCHOOL CHILDREN: A RANDOMISED CONTROLLED TRIAL CM Smuts 1, A Dalton 1, RC Witthuhn 2, P Wolmarans 1 1 Nutritional Intervention Research Unit, MRC, Parow Valley, Cape Town, South Africa 2 Department of Food Science, University of Stellenbosch, Stellenbosch, South Africa

33 RESULTS Cognitive evaluation

34 Intervention effect for HVLT, Reading and Spelling Tests Parameter / Variable Intervention effect (95% CI) P-value Hopkins Verbal Learning Test (HVLT) HVLT: Recognition HVLT: Discrimination Index Reading and Spelling Tests Reading test (T-score) (n: EG = 76; CG = 75) Spelling test (T-score) (n: EG = 76; CG = 75) 0.80 (0.15; 1.45) 1.10 (0.30; 1.91) 2.21 (-0.14; 4.56) 2.81 (0.59; 5.02)

35 ABSENTEEISM (Days absence due to illness) Omega Placebo p-value Any illness Respiratory-related Flu or Cold

36 Effects of iron and DHA/EPA supplementation on PBMC phospholipid fatty acids and morbidity in iron-deficient children in South Africa Linda Malan 1, Jeannine Baumgartner 1,2, Michael B Zimmermann 2, Philip C Calder 3 and Cornelius M Smuts 1 1 Centre of Excellence for Nutrition, North-West University, Potchefstroom, South Africa 2 Human Nutrition Laboratory, Institute of Food, Nutrition and Health, ETH Zürich, Switzerland 3 Institute of Human Nutrition, School of Medicine, University of Southampton, Southampton, United Kingdom

37 Study design

38 Days absent due to respiratory symptoms Fe: Treatment effect: DHA/EPA: FexDHA/EPA: p=0.068 ns ns

39 Duration of respiratory symptoms Fe: Treatment effect: DHA/EPA: FexDHA/EPA: p<0.001 p<0.001 p=0.004

40 Direct interaction! α-linolenic acid (ALA) Conversion rate*: ALA EPA: < 10 % EPA DHA: < 1 % Desaturation Elongation ID? *Burdge & Calder, 2005 Eicosapentaenoic acid (EPA) Docosahexaenoic acid (DHA)

41 SUMMARY Total fat intake is less important than the type of fat in the diet Decrease TFA intake Replacing SFAs with PUFAs decrease the risk for CHD Importantly, increase omega-3 PUFA intake is essential to meet EFA and long-chain PUFA requirements Always dietary fat guidelines should emphasise the total fat intake, taking energy balance into account and ensuring that the optimal intake of EFAs and long-chain PUFAs are addressed

42 SUMMARY To improve the quality of fat intake, it is recommended that SFAs are replaced with PUFAs & MUFAs, rather than only concentration on lowering of total fat intake as a means of lowering SFA intake

43 CONCLUSIONS Current evidence highlights the importance of the type of fat in the diet Fats are an essential component of the diet as they provide EFAs that are precursors of hormone-like substances that influence and regulate key physiological functions Adequate intake of EFAs, especially omega-3 longchain PUFAs, is recommended to promote neurodevelopment and cardiovascular health, and to prevent degenerative diseases at all stages of the life cycle

44 CONCLUSIONS Based on the evidence from prospective and RCTs, emphasis should be placed on the intake of certain fatty acids, rather than the total amount of fat in the diet (=TC interpretation) Although fat is an important source of energy in the diet, the main message should be to balance energy intake with energy expenditure, in an effort to reach and maintain a normal body weight and to ensure the type of fat consumed promotes health Thus, within the boundaries of energy intake and energy expenditure, the emphasis should be on the type, rather than on the amount, of fat in the diet

45 FOOD BASE DIETARY GUIDELINES FOR SOUTH AFRICA The importance of the quality or type of fat in the diet: a food-based dietary guideline for South Africa Smuts & Wolmarans, 2013 Use fats sparingly: choose vegetable oils, rather than hard fats OR Eat and use the right type of fats and oils in moderation

46 Thank You!

47 FAT Recommendations 20-30% of the daily energy intake. Saturated fat < 10% of the daily energy. Cardiovascular risk <7% energy. Polyunsaturated fats 6 10 % of the daily energy intake. Omega 6, 5-8% and omega 3, 1-2% energy. Trans fats <1% of the daily energy intake. Remainder of the energy from fat should provided by mono unsaturated fats.

Facts on Fats. Ronald P. Mensink

Facts on Fats. Ronald P. Mensink Facts on Fats Ronald P. Mensink Department of Human Biology NUTRIM, School for Nutrition, Toxicology and Metabolism Maastricht University Maastricht The Netherlands Outline of the Presentation Saturated