Nutrition Society Winter Conference 2018: where to find the “truth” on nutrition issues, if there is one.

On the 4th and 5th of December 2018 The Nutrition Society and the Royal Society of Medicine organised a joint conference on Diet and Health in London (#nswinter18). The event is a high-level scientific gathering enlightened by the participation of world leading professors, researchers and students, reporting on the most recent evidence of the effect of dietary choices on our health.

If you are looking for a place where the current state of confusion on many matters of diet and lifestyle could be resolved, I would suggest this is it.

It is however very difficult to get close to the truth.

The human body is an extremely complex machine and the myriad of different possible choices of diet and lifestyle that we make every day are adding many more layers of complexity. It is therefore not useful to look at one isolated study with a small number of subjects and draw conclusions; also, not useful to draw conclusions from correlations and associations in big long term studies, where many variables (diet, product composition, lifestyle, physical activity) may change at the same time and confound the results.

Instead, we have to consider the whole body of evidence on a topic and look at it in its entirety, considering the validity of individual studies and their statistical relevance.

Take for example the issue of saturated fats. Ten years ago, the Food Standard Agency (FSA) was heavily advertising[1] the damage done by saturated fats to consumers arteries and advocating their significant reduction in the diet. More recently we saw the publication of few studies that questioned those recommendation and the science linking dietary fat quality with Cardio Vascular Disease (CVD). Nowadays the villain is sugar, portrayed in the media as poisonous and addictive.

So, what’s the truth?

This conference put to bed the dispute on saturated fats. I have heard Prof. Julie Lovegrove confirming the effect of fat quality (saturated, unsaturated) on key cholesterol indicators and on CVD risk and explaining convincingly the results of the few discordant studies. She also re-iterated the importance of replacing saturated fats with unsaturated fats as opposed to carbohydrates; it is not about low fat, it is about low saturated fats. I also heard Prof. Andrew Salter celebrating the successes of the last 50 years in terms of reduction of saturated fats in the diet and the corresponding reduction in death rate by CVD; he passionately advocated to end the debate on saturated fats – the evidence is overwhelming, and dietary fats have clear effects on cholesterol risk indicators and other metabolic indicators.

Concerning sugars, Prof. Ian Macdonald reviewed the data and recommendations of the SACN report[2].  We need to reduce sugars in the diet, as the excessive amounts we are currently eating are clearly linked to dental health issues in children and to overconsumption of calories in the diet; we need to cut specifically on sugary drinks, as excessive consumption of those is also linked to type 2 diabetes. Clearly, we eat too much sugars, however to call sugars poison it is a step too far and does not help. Instead let’s focus on the strong evidence of the beneficial effects of fibres; as Prof Macdonald said “to reduce one nutrient you have to increase something else” and increasing fibres is a very good idea.  

Many other very interesting subjects were reviewed during the two days: the benefits of fish oils, intermittent fasting and meal patterns, the importance of physical activity to reduce waist circumference even without losing weight, the looming threat of loss of muscle mass in the over 50s and how to delay it, the benefits and drawbacks of different diets, etc.  

One of the things I like to retain is the positive light shone on the Mediterranean diet by different speakers. Compared to other very similar diets, the specificity of the Mediterranean diet is more about the way the food is eaten than the food itself; the aspects of cooking from scratch, conviviality, eating together as family and friends at set times, regular physical activity, etc. are captured as key features of the diet in the diet pyramid of the “Fundacion Dieta Mediterranea”[3].

This is a “truth” easy to believe in.

[1] The Guardian, 5 Feb 2009: https://www.theguardian.com/society/2009/feb/05/fsa-saturated-fats-heart-disease

[2] Scientific Advisory Committee on Nutrition, Carbohydrate and Health report, 2015: https://www.gov.uk/government/publications/sacn-carbohydrates-and-health-report

[3] Diet Pyramid – Fundacion Dieta Mediterranea: https://dietamediterranea.com/piramidedm/piramide_INGLES.pdf