How we evaluate the health effect of the foods we consume is undergoing a conceptual change. Until recently food was judged by content; we valued a food’s nutritional impact by its mineral, vitamin, fat, fiber, and other constituents. Such ingredients were valued because they are required to sustain the biochemistry of our cells. We encouraged eating things purposefully to bolster nutritional reserves, to have an excess of what was needed for life and to avoid chemicals inimical to that purpose. More nutritionally oriented practitioners might encourage consumption of certain foods to stimulate specific organs or biological processes. It was all about what food did for us.

We are approaching a day when the focus will not be on what foods contain but instead how food changes our biome, the microbial life that co-inhabits our bodies. This biome controls our health and wellbeing more than we once imagined.

These thoughts were triggered by a paper in Science that describes how using fecal transplants could affect certain cancer patients. The authors summed up their findings: “… some patients with advanced melanoma who initially did not respond to treatment with an immune checkpoint inhibitor, a type of immunotherapy, did respond to the drug after receiving a transplant of fecal microbiota from a patient who had responded to the drug. The results suggest that introducing certain fecal microorganisms into a patient’s colon may help the patient respond to drugs that enhance the immune system’s ability to recognize and kill tumor cells.” ¹

This idea that the gut biome affects immunotherapy drugs has been around for several years. In 2018, Routyet al reported that patients who responded favorably to such drugs had a greater abundance of Akkermansia muciniphila.  In mice, oral supplementation with Akkermansia muciniphila restored the efficacy of PD-1 drugs in non-responders.² This new paper demonstrated that this technique works in people. This is a big thing.

While this PD-1 information is exciting on its own, it is only a drop in the bucket of recent biome research related to cancer. The cancers known associated with biome have increased so rapidly that I can’t offer a complete list. So far, we know esophageal,³ breast,⁴ gastric,⁵ pancreatic,⁶ gall bladder,⁷and kidney,⁸ cancers each have a distinctive biome. Wherever researchers have pointed their microscopes, they discover microbiomes associated with specific cancers.

It’s not just cancer. Other chronic diseases, including cardiovascular,⁹ diabetes, obesity, epilepsy, arthritis,¹⁰ and fatty liver¹¹ are associated with microbial patterns. Psychological conditions, things we once thought were in people’s heads, are blamed on what is in the gut. These include obsessive compulsive disorder,¹² anorexia nervosa,¹³ ADHD, autism,¹⁴ depression (and acne),¹⁵ and anxiety.¹⁶

We have begun to assess food not for its constituents but for its impact on the gut biome. Akkermansia muciniphila was one of the first added to a list of useful bacteria. Foods that increase relative populations have seen their nutritional appreciation rise. One attractive action associated with Akkermansia is “increased longevity”¹⁷ and this positive association may spill over to any food that increases gut populations of Akkermansia.

We are moving into a new paradigm, “it’s not what’s in the food as much as what the food does to the gut microbiome, what’s inside you” that will matter when valuing the nutritional action of foods. Biome impact will replace nutritional content. The highest praise a specific food can receive may be, “Increases biome diversity and individualization.”

Interestingly, many of the foods we thought were healthy still are.

My mother used to feed me wheat germ when I was a kid, “because it was good for you” and this is still true. But the reasoning why wheat germ is good has changed. Once, it contained the vitamins lost during milling. Then when flour was enriched with the lost vitamins, the rationale why wheat germ was good became it contains zinc and magnesium. Then wheat germ was good because it contains loads of fiber so prevents constipation. Wheat germ trended down as more people worried they had celiac; but wheat germ is good again as now it encourages growth of bacteria associated with lower levels of inflammation.¹⁸

Blueberries have also gone through a similar appraisal evolution. Blueberries were once praised as a source of vitamin C and fiber. Then their high ORAC scores made them exceptionally desirable; they improved antioxidant status.¹⁹ Next it was their phytonutrients, the flavonoids, particularly the anthocyanins, that mattered and made promoted good ‘health’.^20,21 Those nutrients were valued for protecting against cognitive decline.²² In our new paradigm, blueberries are about to be prized for their impact on the gut’s microflora.^23,24

Soybeans, back in the Diet for a Small Planet era, scored high for how closely their amino acid ratios approximated that found in egg white. Then it was their isoflavones that mimicked estrogens that justified consumption; but now, it’s their ability to shift the biome that keeps soy on the ‘healthy food list.’²⁵

Our understanding of nutrition continues to evolve and our appreciation of what is important to maintain health changes as our understanding of biology deepens and broadens. At least that was my original thought as to how I would end this piece of writing. But then I went grocery shopping and noticed how many different bone broths are now for sale and that started another thought.

Bone broth is advertised as the ultimate food for restoring bowel integrity and promoting a healthy biome (I have yet to see solid evidence of this, but let’s ignore that for the moment.).²⁶ This reminded me of a bit of history. When the first restaurants opened in Paris in the 1760s, they offered only clear soups, which were consumed to ‘restore’ health. Restaurants sold restoratives. These broths, or consommé’s, were a fashion statement at the time, part of an ‘enlightened philosophy’ that valued refinement in all things, including food. Bouillon restaurants and their elegant broths were viewed as the ultimate in refinement. Patrons consumed consommé. These broths were concentrated from large quantities of expensive ingredients and made to appear as clear as possible; they were the polar opposite of the simple soups laden with visible and recognizable ingredients eaten by the lower peasant classes. Today’s excitement about bone broth should remind us of this historic fad.²⁷

A hundred years later in 1860 as Louis Pasteur experimented in culturing bacteria, he likely modeled his growth media after these early nutritious broths. When Robert Koch isolated anthrax a few years later in 1882, he used beef broth thickened with gelatin. One can easily imagine that these broths, including those made from bones, if they had such utility for growing bacteria in flasks, could have a positive impact on the gut biome. Bone broths are certainly in fashion today, promoted for their restorative effects, and now as a method for restoring intestinal biomes. They may turn out to be particularly suited for doing so. If the promotional claims eventually prove true, we will have come, full circle to where we were nearly 300 years ago, sipping clear broths.

Forget fiber, forget fresh. Our concept of the evolution of nutritional science, that image of a slow and steady advancement and expansion of knowledge about nutrition (and other things as well), may be partly illusion. Evolution here implies forward progress, progressive change, each new paradigm opens us to a progressively broader, more accurate vision of reality. Life and our understanding of what is good for us may not have changed nearly as much as we think. In a way, we are back where we started; we’ve only come full circle to where we were many years ago.