How evidence-based are

Introduction

Is nutritional science evidence-based? Smith concludes that ‘from low fat to Atkins and beyond, diets that are based on poor nutrition science are a type of global, uncontrolled experiment that may lead to bad outcomes [Ref]. Mayer says that ‘prescribing a diet restricted in carbohydrates to the public was “equivalent to mass murder”[Ref]. Nina Teicholz’s book, The Big Fat Surprise chronicled the bad fat saga.[Ref]. The recent 2015-2020 dietary  for Americans have introduced significant changes in recommendations especially for dietary fat [Ref].

Ancel Keys who established the link between cholesterol and heart disease in the 1960s with the ‘seven-country study’ advocated a low-fat, low cholesterol diet to prevent heart disease. However Keys’s study was flawed because he omitted contradictory data from fifteen countries which he had gathered, leading to criticism of its findings at the time. Nonetheless, the American Heart Association strongly promoted a low-fat diet, which included advocating margarine instead of butter and avoidance of eggs.

Next came the sugar scandal. Sugar is in three-fourths of all packaged foods. Since the 1950s, the sugar industry has promoted the idea that a calorie is a calorie, and that eating a calorie’s worth of sweets is no more likely to make someone obese than any other food. The sugar trade association put the blame for heart disease on saturated fat. For decades, the sugar industry has been commissioning researchers, including the influential Ancel Keys, to echo these claims. The three Harvard scientists who published the classic review paper indicting dietary fats for heart disease in the New England Journal of Medicine in 1967 were paid by the Sugar Association. The trade association also opposed new labels on food that would disclose how much sugar had been added to packaged foods. That problem continues in the present day. In 2015, we learned that Coca-Cola worked with scientists to squash the notion that sugar had anything to do with obesity. This is not a problem only with the sugar industry. 

Marion Nestle has shown that, in nearly two hundred food studies, those funded by industry (compared to no industry support) had a positive ratio of thirteen to one. Food “science” is not only compromised by a dearth of hard evidence but also colored by bias.

Nobody really questioned ‘Salt reduction’ until and it was associated with hypertension and heart attacks. Less maybe good for weight loss because the food becomes so tasteless that Sir George Pickering once said, “To stay on it requires the asceticism of a religious zealot.”  A 2018 study of more than 95,000 people in eighteen countries, while verifying a modest increase of blood pressure (with increasing sodium ingested as reflected by urine measurement), showed that the bad outcomes only occurred when sodium intake exceeded 5 grams per day. The average American takes in about 3.5 grams of sodium per day. In fact, for less than 5 grams per day of sodium, there was an inverse correlation between sodium intake and heart attack and death.

Introduction 

the so called facts of Fats, Sugar & Salt

How much of dietary advice is based on reliable evidence?

Are diets mass murder – Smith

Basics – CHO, Facts & Proteins. What is a Calorie?

Nutritional plate

Fat Facts – Saturated, Diary – The Big Fat Surprise book

CHO – glycaemic index

Gut microbiome, personalized diet

Cofee, chocolates, red meat,

Guidelines – what and whom to believe?  

 

 

 

  
  • Large, rapid weight loss is associated with poorer long-term weight-loss outcomes, as compared with slow, gradual weight loss.
  • A bout of sexual activity burns 100 to 300 kcal for each participant
New engl j med 368;5 nejm.org january 31, 2013 449
  • Cardiovascular disease and death are increased with low sodium intake (compared with moderate intake) irrespective of hypertension status.
www.thelancet.com Vol 388 July 30, 2016
  • Coffee consumption seems generally safe within usual levels of intake, with summary estimates indicating largest risk reduction for various health outcomes at three to four cups a day, and more likely to benefit health than harm.
BMJ 2017;359:j5024 | doi: 10.1136/bmj.j5024
  • There is no evidence of association between chocolate intake and risk of CHD, stroke, or both combined in participants free of preexisting major chronic disease.
Am J Clin Nutr 2018;108:41–48.
  • The frequent consumption of fried potatoes appears to be associated with an increased mortality risk.
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Am J Clin Nutr 2017;106:162–7.
  • There is no compelling evidence to indicate important health benefits of non-sugar sweetener use on a range of health outcomes
BMJ 2019;364:k4718 | doi: 10.1136/bmj.k4718
  • The risk of coronary heart disease is reduced by replacing saturated fat with polyunsaturated fats (including plant oils) but not when carbohydrate is the replacement nutrient.
BMJ 2018;361:k2139 doi: 10.1136/bmj.k2139

There is good quality evidence that increasing omega-6 fats reduces cardiovascular outcomes in primary and secondary prevention.

 

Cochrane Database Syst Rev. 2018 Nov 29;11:CD011094

Increasing polyunsaturated fatty acids (PUFA) intake reduces effect on all-cause or cardiovascular disease mortality.

 

Cochrane Database Syst Rev. 2018 Jul 18;7:CD012345