Once I inform folks about what I do for a dwelling (a meals scientist), I invariably get the identical response. A roll of eyes and criticism about how the issue with meals science is that it’s all the time telling me that crimson wine is nice, then it’s unhealthy, then it’s good, relying on the day of the week. The reality is that the sector of dietary epidemiology, the examine of huge populations and the way the meals they eat impacts their well being, has struggled for a while with very unhealthy PR.
This unhealthy PR stems from the truth that these research normally depend on what folks inform us they eat, and never what they really eat. This may work effectively for some facets of the weight loss program – dietary patterns, for instance – however not others, particularly particular person meals or meals elements.
There are two most important issues: first, folks don’t all the time appropriately report what they eat and usually declare to eat extra of what’s thought-about to be wholesome and fewer of what’s thought-about to be unhealthy. This impacts the correlation we observe and typically even reverses the end result. As an example, self-reported sugar consumption is related to a decrease physique mass index (BMI), whereas we’ve proven beforehand that precise sugar consumption is unsurprisingly related to the next BMI. This drawback is well-known and has been mentioned amongst nutritionists for many years. There are some subtle strategies to deal with this, however they’re not all the time attainable to make use of.
The second is tougher to deal with however has arguably a a lot bigger affect when investigating particular person compounds, equivalent to nutritional vitamins, minerals or bioactives equivalent to caffeine or flavanols – meals is just not standardised. The variability in meals composition is big, even in meals harvested from the identical plant. Within the 1960s, researchers analysed the composition of apples on a single tree and located greater than twofold variations within the composition of those apples. Additionally, composition modifications throughout storage and, after all, preparation. Nevertheless, in diet analysis, we frequently should depend on printed meals composition knowledge and use a single worth. For instance, for every apple, we assume it comprises 9mg of vitamin C, when in actuality, this may be very totally different.
What does this imply? It signifies that it’s unimaginable to estimate the precise consumption of a compound primarily based on dietary knowledge and meals composition knowledge alone. A cup of tea comprises between 1mg and 600mg whole flavanols. But in most analyses, this can be standardised to 125mg per cup. This has big penalties, because the estimated consumption of flavanols now not depends upon the precise consumption, however merely the consumption of sure meals. Most research performed to this point have this weak point.
Nearly ten years
The easiest way to deal with this drawback is by measuring what’s taken up by the physique, utilizing so-called biomarkers. We will do that for instance in urine, but additionally in blood and hair. This technique tells us precisely what an individual has consumed and doesn’t depend on meals composition knowledge or the particular person telling us what they ate. However this strategy is pricey and wishes lots of preparation, which is the explanation there haven’t been many large-scale research to this point.
We determined to make use of this strategy to research the affiliation between flavanols and blood stress. Flavanols are present in a variety of meals, equivalent to tea, apples, wine and cocoa. A number of smaller research have proven a helpful impact on blood stress, and their impact on heart problems danger is presently being investigated in a big trial. There’s, nonetheless, no dependable knowledge on their impact in most of the people when consumed as a part of a traditional weight loss program.
Such a challenge required lots of planning and preparation, and it took nearly ten years from begin to end. We needed to establish probably the most appropriate biomarkers first after which develop analytical strategies. Our colleagues from the College of California, Davis, in addition to meals producer Mars Inc., performed groundbreaking analysis into the metabolism of flavanols in people and developed strategies to synthesise these metabolites so we might establish probably the most promising biomarkers and set up that they supply an correct estimate of consumption. On the similar time, our colleagues from EPIC Norfolk and the MRC Epidemiology Unit, in addition to from LGC Fordham Laboratory, arrange the infrastructure to course of greater than 25,000 urine samples.
The outcomes of the examine had been thrilling: for the primary time, we might present that there was a statistically vital, significant distinction in blood stress of 1-3mmHg between these with excessive and low-flavanol consumption. This distinction is just like the impact of lowering salt consumption or adopting a Mediterranean weight loss program.
There was a way more necessary discovering, although. When evaluating objectively measured flavanol consumption with knowledge estimated utilizing the standard technique, we discovered solely a really weak correlation. This exhibits that combining self-reported knowledge with meals composition databases is unlikely to supply a dependable estimate of flavonol consumption – and the identical might be true of many different compounds with excessive variability in meals composition.