‘Often too little evidence for general claims about a healthy lifestyle’
‘A lot of general advice about healthy lifestyles is based on observational studies which, however, do not provide enough evidence to be able to make reliable claims for every individual.’ So said Prof Thomas Unger during his farewell speech today at Maastricht UMC+ / Maastricht University. Unger is stepping down as director of the Maastricht research institute CARIM, which specialises in research on cardiovascular disease. Chemical biologist Prof Tilman Hackeng will fill that position from 1 April 2017.
In the scientific world, it is not unusual to set up large cohort studies. These involve large groups of people who are used to study a specific cause/effect relationship, such as the one between salt consumption and the development of cardiovascular disease. Over the years, researchers use measurements to examine which people develop a heart condition. ‘If it appears that people who ingest six grams of salt per day have the least risk of developing cardiovascular disease, newspapers across the entire world broadcast that finding a day later’, Unger explains. ‘However, you cannot link these studies to sound advice that applies to every person.’
Let’s continue with the salt example. For many years, the general population in the United States has been advised to ingest about six grams of salt per day. However, various studies have shown that this advice does not apply to everyone. It turns out that it is only the recommended dose for people who already have high blood pressure and an excessive daily salt intake (about 10 percent of the population). For many people, six grams of salt per day would be inappropriately low. There are numerous examples of situations in which general recommendations are based on observations from large cohort studies. ‘These health claims should not be generalised’, Unger says. ‘The actual effects of foods and lifestyle are complex and can be different for each individual. If I were going to offer one piece of health advice, it would be to eat a diverse diet and split the portions in two.’
Unger’s farewell address was titled: 'Truth, Post-Truth and Disease Prevention in Times of Healthy Living'. Since 2012, Prof Thomas Unger has been the scientific director of the CARIM research institute at Maastricht UMC+ / Maastricht University. From 1 April 2017, he will be succeeded by Prof Tilman Hackeng.