I wish I had spent more time trying to understand Chemistry 101, instead of just worrying about flunking it. Because as the debate rages on about which is better for you: Paleo or Keto, Vegan or Mediterranean, there is one inarguable fact: Food is chemistry. And how it affects our bodies starts moments after we eat. When those molecules reach the intestines they turn on and off the bacteria growing in our gut, which in turn determines our future heart health, cellular function, and day-to-day energy level.

We hear a lot about the "microbiome," which is basically a fancy word for the bacterial growth and environment in our intestines, and whether the bacteria that grows there is "good bacteria" that promotes healthy cellular function or "bad bacteria" that can lead to heart disease and other ailments. The bacteria that grows is determined by what we eat.

Your gut bacteria send out signals (chemical compounds) via the bloodstream to tell your body to either brace itself for incoming fat and animal protein or get soothed and sustained by plant fiber and antioxidants, and natural nutrients that grow in the ground.

Never a chemistry or biology jock, I need to let the experts explain how this works: For that, I went to visit Dr. Hooman Yaghoobsadeh, a well-known cardiologist at New York Hospital, who is also on the faculty at Weill Cornell Medical School, who happens to be my doctor, and also just coincidentally espouses a plant-based diet for long-term (and short-term) health. 

When I told Dr. Y that I had gone plant-based a year after first meeting him he got so excited that he invited me up to his office for a 45-minute lecture that he gives to medical students and others around the country, to show how a plant-based diet works to reverse heart disease and stave it off in those who are still symptom-free. (Other cardiologists have since told me that if we are over the age of 18 and eat a traditional American diet, we all have heart disease, it's just that half of us don't know it yet.) I arrive at Dr. Y's office and am immediately given a lecture that takes me back to my Intro to Chem days, though this time I  pay rapt attention, and this time, I understand what's at stake.

Let's start with a few key facts (get ready to pay attention since there are some freaky factoids here, which would have kept me from failing Chem if this had been part of the lecture). Such as the fact that there are more than 2 million bacteria-owned genes in your gut, more even that the number of genes in the human cells that make up your body. And these bacteria genes drive more of your health than the genes you were born with.

1. There's more DNA that is bacteria in your body than in your human cellular self.

In your gut, you have 300 to 500 bacterial species, which together represent 2 million genes -- which makes up your microbiome. So the DNA of the bacteria in your gut is approximately 10 times that of all of the cells in your body. The collective bacterial genome is like the Milky Way galaxy, compared to the Solar System of our human genome.

2. We are what we eat. And we can change that for the better. It happens quickly.

That means that when you change what you eat, you literally change what and who you are. We can change who we are in just six weeks. In fact, it starts to happen in just 4 days.

The microbiome and us humans co-evolved over 200 million years, but only in the last minute hundreds of years have we increased the amount of meat we eat, and when you go off that animal product, it takes about 4 days to alter your gut bacteria and switch over from meat-metabolizing to plant-metabolizing, and that changes the whole system. The dietary influence of your food choices is more important on your health than the DNA you got from mom and dad.

3. Plant-eating bacteria keeps blood sugar steady, insulin low and not store sugar as fat.

When you feed humans plants, their gut switches over from animal bacteria to plant bacteria. And when you do that, your entire body reacts differently.  Fiber-eating bacteria are programmed to degrade the fiber in plants. It helps your food move through the body's digestive tract and your intestines without raising blood sugar and causing insulin to spike, which signals the body to store extra sugar as fat.

So by eating more fiber in every meal, and keeping the fiber to carb ratio at 4 or higher (more fiber, less simple carbs) you keep blood sugar steady and insulin levels in check, all good if you're trying to maintain a healthy weight.

Fiber is the key to modern-day health, says Dr. Yaghoobzadeh. When you move away from animal products you make more room for fiber in your diet. Animal proteins go rancid -- which is why the bacteria in your gut that feed on animal proteins are inflammatory.

Every major disease is linked to inflammation. Dr. Yaghoobsadeh calls it the first domino in most diseases. When that domino falls -- meaning inflammation in the body spikes -- it affects insulin, it can lead to heart disease, and it can lead to arthritis and slowness to recover from injury.

4. Meat-eating bacteria tell your blood vessels to constrict, harden and clog up with plaque.

When you eat animal products, the bacteria shift to meat-eaters and your system goes into overdrive to fight off invaders, and cellular inflammation is the first line of defense when this happens. Your body's immune system is triggered not just by viruses but by the food you eat, and it can result in symptoms as varied as arthritis, achy joints or puffiness, and bloat. It may not be the sodium in your BBQ, but the meat itself that gave you all those puffy achy feelings.

5. TMAO is not anything like LMAO. It's much much scarier.

Animal protein makes TMA in your gut which the liver turns into TMAO, a chemical compound that travels in the blood and instructs the body that lipids are present and need to be dealt with. Too much TMAO signals the body to start stiffening up the arteries as fatty molecules or lipids pass through. This chronic barrage of animal fat can't get cleared quickly enough by the bloodstream, and plaques form, creating blockages in important blood vessels, raising blood pressure, requiring the heart to work harder to move the blood through these impasses to circulate to the body, and ultimately you end up with heart disease. The more animal protein patients ate, in studies Dr.Yaghoobsadeh can enumerate, the higher their rates of heart disease.

The more plants that patients ate the lower their rate of heart disease. A heart-healthy diet is one that is high in fiber and lower in animal products. It's not all or nothing, but it is helpful to realize that the gut bacteria is ruling these processes, so the more plants you eat the better.

6. Bottom line: It only takes 4 days to shift from bad bacteria to good. And that is helpful!

The less animal product you eat, the healthier your gut balance will be. It only takes 4 days to shift the balance from bad bacteria to good bacteria, so if you eat meat, know that you can reverse all these processes in less than half a week. It's that fast. And if you don't eat meat but you slip up, move on and get back on track, because a little bit of animal or dairy product is not enough to turn back on the bad bacteria. You have to do it repeatedly for days in order to have the gut switch back over to meat-eating bacteria.

Once you shift over to a mostly plant-based diet the gut bacteria shifts over too, and the new fiber-eating bacteria can't select or break down the TMA, so it just slips past the whole process. Your metabolism shifts over after about six weeks to not be able to break it down. That means your system burns on healthy fiber-based foods, and the others just go unnoticed. Of course, if you begin to shift back to animal products consistently, your gut will readjust too, but the occasional spec of cheese, meat or dairy is not enough to trigger that.

7. How much protein do I need? Max: 55 grams a day for active women or 65 grams for men.

That means that if you tell yourself you're eating animal products for protein, you don't need to. For the best sources of plant-based proteins, including vegetables, fruits, nuts, seeds, and grains, check out The Beet's story on the top sources of protein. A bowl of oatmeal with almond or oat milk delivers 10 grams, a Quinoa and lentil or chickpeas salads delivers another 20 grams for lunch. Snack on hummus, a handful of almonds or pumpkin seeds, then plan a stir fry and tofu over rice for dinner and you are good for the day. There is not much more to chemistry than that.