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In an effort to slash heart disease, the Dietary Guidelines for Americans [1] have since 1977 been urging people to:

1. Reduce total fat consumption to 30% of total caloric intake.

2. Reduce saturated fat consumption to 10% of total energy intake.

Government issued dietary guidelines are highly authoritative and regarded by a majority as being backed by solid research. However, as it turns out, this is not the case…

Dietary recommendations regarding intake of total and saturated fat are highly controversial, and the debate is heating up. A recent systematic review and meta-analysis of six studies that were available 1977, when the first version of the Dietary Guidelines for Americans was published, shows: [2]

- Dietary interventions that reduce total and/or saturated fat intakes result in no differences in all-cause mortality, and non-significant differences (meaning could be due to chance) in coronary heart disease mortality.

- While lower total fat and saturated fat intakes led to significant reductions in mean total cholesterol levels, this did not result in significant differences in coronary heart disease or all-cause mortality.

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NOTE:

As I described in a previous article, total cholesterol levels tells nothing; it is a far too crude measure. One has to look at each cholesterol and lipoprotein fraction, and their respective particle distributions, in order to get an idea about the cardiovascular risk profile. I covered this in more detail in a previous article “Blood Cholesterol Testing – don’t let the routine standard lipid panel fool you!”

In the context of this discussion, it is notable that replacing carbs with fat beneficially reduces atherogenic lipoprotein (i.e. cholesterol carrying) particles.[3]

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Thus, the available randomized controlled trials (RCT; the gold standard type of study in scientific nutrition research [4, 5]) clearly did NOT support the introduction of these dietary fat recommendations in order to reduce heart disease and mortality.

Astonishingly, five of the six RCTs did not even examine either a total fat consumption of 30%, or a saturated fat consumption of 10%, of energy intake.[2] The trials investigated administration of vegetable oil, the replacement of saturated fats with vegetable oil, and an approximate 20% fat diet. Only one single RCT examined the consequence of a 10% saturated fat diet… and here comes the kicker… reported a HIGHER incidence of all-cause mortality and coronary heart disease deaths in the low saturated fat group.[6]

The conclusion from this analysis is:

Dietary advice [on fat intakes] not merely needs review; it should not have been introduced.

Comments

Since the 1980s we have been indoctrinated by supposedly authoritative guidelines to believe that dietary fat, and especially saturated fat, is “bad”. Even the most uneducated citizens know how “bad” it is it to eat fat, right!?

This undue focus on total fat and saturated fat as a dietary villain for heart disease has greatly distracted attention away from the risks posed by other foods and nutrients, such as carbohydrates [7-12], processed foods [13-16], and fruits/vegetables.[17-20] In addition, we have to remember that it is not just about eating too much of something harmful; too little of something health promoting may be as deleterious for our health and wellbeing. This brings up the issue of reductionism vs. holism [21], i.e. the importance to look at the whole dietary picture. This is especially important when it comes to saturated fat intakes, as the carbohydrate content of the overall diet will tremendously impact how the body metabolizes ingested fats.[22, 23] In addition, if you reduce intake of one thing, what you replace it with may be even more important.[8, 24]

Perhaps the most disturbing issue is that guidelines originating from authorities are supposed to be evidence based; meaning, based on the totality of evidence.[25] Thus, even if the government issued dietary goals back in 1977 were wrong, one would expect that the accumulating body of scientific evidence over the past few decades, showing that dietary fat is not a villain [26-32], would have impelled the authorities to modify their recommendations….not so!

We can only hope that the 2015 edition of the Dietary Guidelines for Americans – after 38 years – will embrace the fact that science (including nutrition science) is an evolving discipline and finally update their old-school low-fat mantra … the world is not flat anymore!

References:

1. Needs., S.C.o.N.a.H., Dietary goals for the United States. 1st edn. . 1977: Washington: US Govt Print Office.
2. Harcombe, Z., et al., Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis. Open Heart 2015. 2: p. e000196.
3. Volek, J.S., M.J. Sharman, and C.E. Forsythe, Modification of lipoproteins by very low-carbohydrate diets. J Nutr, 2005. 135(6): p. 1339-42.
4. Concato, J., N. Shah, and R.I. Horwitz, Randomized, controlled trials, observational studies, and the hierarchy of research designs. N Engl J Med, 2000. 342(25): p. 1887-92.
5. Benson, K. and A.J. Hartz, A comparison of observational studies and randomized, controlled trials. N Engl J Med, 2000. 342(25): p. 1878-86.
6. Woodhill, J.M., et al., Low fat, low cholesterol diet in secondary prevention of coronary heart disease. Adv Exp Med Biol, 1978. 109: p. 317-30.
7. Hite, A.H., V.G. Berkowitz, and K. Berkowitz, Low-carbohydrate diet review: shifting the paradigm. Nutr Clin Pract, 2011. 26(3): p. 300-8.
8. Kuipers, R.S., et al., Saturated fat, carbohydrates and cardiovascular disease. Neth J Med, 2011. 69(9): p. 372-8.
9. Volek, J.S., et al., Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids, 2009. 44(4): p. 297-309.
10. Feinman, R.D., Fad diets in the treatment of diabetes. Curr Diab Rep, 2011. 11(2): p. 128-35.
11. Wylie-Rosett, J., et al., Health effects of low-carbohydrate diets: where should new research go? Curr Diab Rep, 2013. 13(2): p. 271-8.
12. Bazzano, L.A., et al., Effects of low-carbohydrate and low-fat diets: a randomized trial. Ann Intern Med, 2014. 161(5): p. 309-18.
13. Birlouez-Aragon, I., et al., A diet based on high-heat-treated foods promotes risk factors for diabetes mellitus and cardiovascular diseases. Am J Clin Nutr, 2010. 91(5): p. 1220-6.
14. Uribarri, J., et al., Advanced glycation end products in foods and a practical guide to their reduction in the diet. J Am Diet Assoc, 2010. 110(6): p. 911-16 e12.
15. Semba, R.D., E.J. Nicklett, and L. Ferrucci, Does accumulation of advanced glycation end products contribute to the aging phenotype? J Gerontol A Biol Sci Med Sci, 2010. 65(9): p. 963-75.
16. Stirban, A., T. Gawlowski, and M. Roden, Vascular effects of advanced glycation endproducts: Clinical effects and molecular mechanisms. Mol Metab, 2014. 3(2): p. 94-108.
17. Wang, X., et al., Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies. BMJ, 2014. 349: p. g4490.
18. Leenders, M., et al., Fruit and vegetable intake and cause-specific mortality in the EPIC study. Eur J Epidemiol, 2014. 29(9): p. 639-52.
19. Hartley, L., et al., Increased consumption of fruit and vegetables for the primary prevention of cardiovascular diseases. Cochrane Database Syst Rev, 2013. 6: p. CD009874.
20. Oude Griep, L.M., et al., Colours of fruit and vegetables and 10-year incidence of CHD. Br J Nutr, 2011. 106(10): p. 1562-9.
21. Fardet, A. and E. Rock, Toward a new philosophy of preventive nutrition: from a reductionist to a holistic paradigm to improve nutritional recommendations. Adv Nutr, 2014. 5(4): p. 430-46.
22. Forsythe, C.E., et al., Limited effect of dietary saturated fat on plasma saturated fat in the context of a low carbohydrate diet. Lipids, 2010. 45(10): p. 947-62.
23. Volk, B.M., et al., Effects of step-wise increases in dietary carbohydrate on circulating saturated Fatty acids and palmitoleic Acid in adults with metabolic syndrome. PLoS One, 2014. 9(11): p. e113605.
24. Siri-Tarino, P.W., et al., Saturated fatty acids and risk of coronary heart disease: modulation by replacement nutrients. Curr Atheroscler Rep, 2010. 12(6): p. 384-90.
25. Blumberg, J., et al., Evidence-based criteria in the nutritional context. Nutr Rev, 2010. 68(8): p. 478-84.
26. Malhotra, A., Saturated fat is not the major issue. BMJ, 2013. 347: p. f6340.
27. DiNicolantonio, J., The cardiometabolic consequences of replacing saturated fats with carbohydrates or Ω-6 polyunsaturated fats: do the dietary guidelines have it wrong? Open Heart 2014. 1: p. e000032.
28. Hite, A.H., et al., In the face of contradictory evidence: report of the Dietary Guidelines for Americans Committee. Nutrition, 2010. 26(10): p. 915-24.
29. Siri-Tarino, P.W., et al., Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr, 2010. 91(3): p. 535-46.
30. Micha, R. and D. Mozaffarian, Saturated fat and cardiometabolic risk factors, coronary heart disease, stroke, and diabetes: a fresh look at the evidence. Lipids, 2010. 45(10): p. 893-905.
31. Ravnskov, U., et al., The questionable benefits of exchanging saturated fat with polyunsaturated fat. Mayo Clin Proc, 2014. 89(4): p. 451-3.
32. Ramsden, C.E., et al., n-6 fatty acid-specific and mixed polyunsaturate dietary interventions have different effects on CHD risk: a meta-analysis of randomised controlled trials. Br J Nutr, 2010. 104(11): p. 1586-600.

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Monica Mollica holds a Master Degree in Nutrition from the University of Stockholm and Karolinska Institue, Sweden. She has also done PhD level course work at renowned Baylor University, TX.

 

Monica is a medical writer, diet/supplement/health counselor and body transformation coach, and a regular contributor to www.BrinkZone.com.

 

Check out Monica's website:        www.Ageless.Fitness

 

She can be contacted via email:   Monica@Ageless.Fitness

 

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