Do whole grains prevent heart disease?

23 Sep 2023 | Data is not evidence

Study: Whole Grain Consumption Lowers Death Risk

That’s the title of an article in HCP Live, a clinical news and information portal for doctors. It’s consistent with what everyone tells you about the benefits of whole grains. But while some superfoods are peddled out of thin air, this one seems to be backed up by evidence. And not just any evidence, but a study published in the prestigious Journal of the American Medical Association network.

The researchers had a wealth of data. They studied the dietary habits of 74,341 women and 43,744 men over decades. In total, they had 2,727,006 person-years and 26,920 deaths. The conclusion was clear: people who ate more whole grains lived longer. In the authors’ words: “Every serving of whole grain (28 grams daily) was associated with a 5% lower total mortality or a 9% lower cardiovascular disease (CVD) mortality.”

But that’s only a correlation; it’s not causation. People who choose to eat whole grains might differ from those that don’t in many other ways. Perhaps they’re wealthier, because whole grains are more expensive than fast food, and their wealth gives them better housing, superior healthcare, and an easier life — all of which help them live longer. Or, since whole grains have a healthy allure, devotees of clean living are more likely to consume them, and its their clean living that boosts their health. This is an example of why data is not evidence: it may not be conclusive if it’s consistent with alternative explanations.

This problem extends to any study examining a voluntary choice, because people who make that choice might be special in other dimensions. Instagram influencers endorse weight loss supplements — but people who choose to buy a supplement are likely taking other actions to shed pounds, such as exercising more, eating better and drinking less. Those actions could be causing the weight loss, not the supplement. Motivational speakers reel out testimonials from devotees whose lives were changed after attending their seminars — but those willing to shell out hundreds of dollars and drive for six hours to hear a talk are likely taking other steps to better themselves. Those actions could be causing the turnaround, not the guru’s five-point plan.

Inside the Ivory Tower

Inside the Ivory Tower

In May Contain Lies, I highlight the value of academic research. While it's far from perfect, it can be more reliable than practitioner studies for a number of reasons: Its goal is scientific inquiry, rather than advocacy of a pre-existing position or releasing findings to improve a company's image. It's conducted by those with expertise in conducting scientific research. Papers published in top scientific journals are peer-reviewed, which helpsimprove their accuracy. However, authors, journalists, and practitioners will sometimes cite research as if it bears the hallmark ...
Does only 2% of VC funding go to female founders?

Does only 2% of VC funding go to female founders?

A widely quoted statistic is that only 2% of VC funding goes to female founders. For example, this Forbes article highlights that "only 2% of all VC funding goes to women-led startups" and asks "Why is only 2% of VC funding going to female founders"? If true, this statistic is substantial underrepresentation and needs to be urgently addressed. However, it's problematic for several reasons. 1. The Statistic Ignores Diverse Teams The 2% statistic actually refers to companies founded solely by women. It ignores diverse companies founded by both men and women. This is strange, because ...
An unhealthy obsession with organisational health

An unhealthy obsession with organisational health

Two leading asset management firms drew my attention to the McKinsey Organizational Health Index as a potential tool to evaluate a company. A book, "Beyond Performance 2.0: A Proven Approach to Leading Large-Scale Change", written by two McKinsey partners, claimed that companies with high scores on this Index trounced their unhealthy peers along a range of performance measures. For example, their shareholder returns were three times as high. But as I wrote in an earlier post, rather than being more impressed by big numbers, we should be more sceptical. If it were really possible to ...