Fiber and my top three nutrition takeaways (conversation fodder)

Fiber is having a bit of a moment.

Several papers came out in 2019 suggesting that this form of carbohydrate that our bodies don’t digest is associated with lower incidence of non-communicable diseases and mortality, and may help to promote weight maintenance, if not weight loss (this JAMA viewpoint provides an overview, as does this Vox article).

However, current estimates suggest that the average American (and I’d hazard to guess probably us Canadians too) consumes only half of the recommended 25 g/day for women and 38 g/day for men.

Switching gears for a moment.

In 2019, I obtained my certification in culinary medicine. This process taught me that the world is rife with debate about nutrition (only to be expected when what we eat has the potential to form a large part of our identity, which is also not surprising given that food not only provides the necessary fuel to sustain life, but also forms the hub of many social interactions and cultural traditions). I also learned that the nutrition research sphere is daunting and filled with conflicts of interest (this article was particularly eye-opening for me).

The purpose of this post isn’t to get into all of that, though. It’s more to say that, over the past two years that I’ve been spending every weekend learning about healthy food and how to prepare  it (and how to translate this knowledge to my colleagues and patients), I’ve frequently wondered whether it’s possible to distill everything I’ve learned about nutrition into a few main takeaway points.

It’s not.

But I’m still going to try.

Returning to fiber now, I was reading this article from ConsciensHealth, which discusses a recently published systematic review and meta-analysis by John Sievenpiper’s group out of Toronto (to really bring things full-circle, Dr. Sievenpiper has conflicts of interest of his own — he has reported funding from various players in the ‘Big Nut’ and ‘Big Carbohydrate’ game, which seem worth mentioning). This study showed that interventions to increase soluble fibre intake (which can be achieved through ingestion of things like oats, or dietary supplements containing things like psyllium [Metamucil], guar gum, and beta-glycans), even in the setting of ad libitum intake (i.e. where people eat as much as they want, not formally restricting calorie intake) are associated with a statistically significant decrease in weight. The only catch being that although the decrease was statistically significant, it was 0.33 kg compared to usual diets. That’s less than a pound, so I would argue that it’s not exactly clinically significant. Most of us probably wouldn’t notice if we lost less than a pound, and many (most?) of us fluctuate in weight by more than that amount each day.

All things considered, though, increasing our fiber intake seems like a strategy with few downsides (although start low and go slow if you want to keep your bowels under control, and those whose bowels tend to sway on the irritable side may want to avoid certain types of fiber called fructans) to help manage weight and prevent chronic disease.

In fact, if I had to pick my top three nutritional strategies, increasing fiber intake would absolutely make the cut. This list isn’t meant to be comprehensive, but here are my current top three (keeping in mind consistent new evidence accrued over time might start to change this):

  1. Increase our intake of fiber, especially vegetables and fruits. Aim for five a day! Oats are good too.
  2. Increase our intake of whole, unprocessed foods. The corollary to this is that we should decrease our intake of processed food with lots of additives like sugar, salt and preservatives. It’s been said that if you aren’t hungry enough to eat an apple, then maybe you’re not really hungry.
  3. Increase the amount of time we spend fasting. Leaving a 12 hour window each day in which you don’t consume any calories may permit ‘metabolic switching‘, resulting in benefits for weight, sleep, and prevention of chronic disease.

If you asked me to make a comment on non-diet related health recommendations (yeah, I know, you didn’t ask), I’d also throw in getting regular exercise (in a way that is enjoyable and sustainable to you), and getting 7+ hours of sleep a night.

If you like getting simple health advice, I’ll leave you with Yoni Freedhoff’s recent New York Times article (paywall): How to Be Healthy, in just 48 words.

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