This is the text that I published in the International Fruit and Vegetable Juice Association news letter.
Introducing the elephant in the room
“When there's an elephant in the room, you can't pretend it isn't there and just discuss the ants. ” ― Ellen Wittlinger
When we talk about fruit and vegetables we often praise their obvious properties that typically come to us from popular culture. Iron in spinach, vitamin C in orange juice, or the phytonutrients and antioxidants that give fruit and vegetables their beautiful color. What is often mentioned in passing is that fruit and vegetables also contain fiber. This is akin to someone studying the gravitational pull of the planets and the moon on Earth, and mentioning in passing that the sun is a beautiful star when in actual fact it accounts for over 99% of all gravitational forces on planet earth.
The same is likely true for fiber: It is the root cause behind the vast health benefits of fruit and vegetables, but somehow we seem to pay more attention and money for drinks with super-fruits, antioxidants, and vitamins. The average consumer barely takes notice of the fiber content.
There is a sizable body of research and meta-analyses that show that for every additional gram of fiber, all-cause mortality is reduced by 1%. In other words, if we consume the amount of fiber we ought to consume (about 10g more than we consume on average), this would translate into a 10% reduction in all-cause mortality. Increasing fiber consumption, therefore, will add many years of healthy and enjoyable life. To put this in context: there is no drug or other health intervention on earth that can do this on a mass scale. The covid-19 vaccination does not even come close to saving lives (maybe the Smallpox immunization).
All-cause -mortality is the most rigorous way to measure a health benefit because it measures all positive and negative effects. Given the powerful impact of fiber on all-cause mortality, the immediate question is whether fiber also has a beneficial effect on specific diseases? The answer is a resounding yes! Fiber reduces the risks of the big killers such as cardiovascular disease, or certain cancers by double-digit percentages, due to fiber’s profound impact on our digestive, metabolic, hormonal, immune, and cardiovascular systems. This happens through its direct chemistry (e.g., absorption of sugar) and through its indirect chemistry, as a result of the metabolites formed by our gut bacteria when they ferment fiber (e.g., short-chain fatty acids). The extensive evidence from observational studies is also supported by intervention studies for a range of disease markers, like obesity, blood lipids, LDL cholesterol, blood pressure, systemic inflammation, or IBS.
Much research has focused on looking for the beneficial impact of individual natural ingredients found in this or that super-fruit in part because of the hope that they could be patented. But remember that when people test one benefit, such as reduction of a disease marker, they often do not look at any side effects that may balance the positive. So something that is beneficial for cardiovascular health, may cause certain cancers, thus undoing some or all of its positive value. Fiber does not suffer this. Its benefits suffice to explain the lion's share of the health-promoting value of fruit, vegetables, seeds, grains, nuts, herbs, etc. (thus the all-cause-mortality evidence).
“When there’s an elephant in the room introduce him.”― Randy Pausch
In summary, there is a very high likelihood that the main health-enhancing effect of whole fruit and vegetables is due to the presence of fiber. When we produce a juice we remove a substantial part of this fiber and it is imperative for all producers to find ways of adding that life-giving fiber back into the consumer product. Fiber is not a mega-trend yet, but don’t be caught off guard, because it certainly will be.