The microbiome is composed of a balance between bacteria & bacteriophages (viruses that infect bacteria), and one between bacteria & fungi.
Why is our Microbiome in our GI Tract Important?
Question: Does taking all vitamins replace the need to eat vegetables? If not, what am I missing out on?
Each of the answers so far makes good and bad points. So they are definitely worth reading. But the fiber issue is just the tip of the iceberg, the bulk of it is the microbiome. Gut bugs (bacteria, fungi, bacteriophages, etc.) are a necessary and essential aspect of our health that we do not understand sufficiently to replace with pills. For example, we can only culture (in a scientific laboratory) roughly 1% of the bugs that we know live in the healthy human gut. If we can’t keep our essential gut bugs alive, how can we substitute for not eating vegetables? If we can’t replace missing bugs by growing them outside the body and implanting them, how can we stop eating vegetables?
We know the bugs are there because of their DNA signatures. So at this time, the ecology of the gut is beyond the ability of science and medicine to replace it.
There certainly may be other health benefits to eating vegetables. Phytotoxins, for example, play a huge role in up-regulating liver enzymes that detoxify other chemicals in our bodies. This is why eating broccoli and other cruciferous veggies lowers your cancer risk. It may sound counter-intuitive, but eating a diet highest in a broad range of phytotoxins seems to offer the greatest health benefits. Many of these phytotoxins are mitogens, carcinogens and teratogens, so “natural” toxins are not fundamentally different from non-natural toxins in the most general use of the word toxin.
I think it might surprise some readers to learn that the benefits of fiber are not directly from the fiber, but rather from the fiber-digesting bugs of the microbiome. If those butyrate-producing microbes are missing from the microbiome (because of indiscriminate use or careless over-use of antibiotics, for example), the anti-colon cancer benefits of fiber are hugely reduced or gone altogether. This is a good illustration of the necessary and essential role of the microbiome in human health.
The proper role of vitamins and supplements is (1) to decrease the chance of having a functional metabolic bottleneck from too-low nutrient levels in one’s diet, and/or (2) to raise key nutrients to more beneficial levels than can be accomplished by eating foods (or by eating only the foods that you want, like or can afford to eat). For example, if you want resveratrol and choose NOT to drink red wine, you can take a supplement. As another example, you have a clotting tendency and want a higher vitamin E level, without higher PUFAs, vegetable phosphatidylcholine or phytoestrogens.
The take-home message: avoiding veggies is a prescription for disaster. [Source]