What’s Taurine and Why Do We Care? (Part 3)

Foods that contain the highest levels of taurine come from the sea, particularly seaweed and shellfish. The most concentrated source, though, is dried nori, the seaweed sheets used to make sushi.

Land plants, however, have negligible amounts. So, a singular focus on increasing dietary taurine risks driving poor nutritional choices, because plant-rich diets are associated with human health and longevity. I mean, energy drinks have taurine too, but slamming monster Red Bull rockstar cocaine is probably not the best option. The best choice would probably be to eat a healthy plant-based diet with supplemental taurine. It’s such a simple molecule; it can be inexpensively synthesized. So, you can just get pure taurine powder.

Here’s how it all breaks down. We can start with concentration. Pure taurine obviously has the most, then dried nori, then an average of clams, oysters, mussels, and scallops, then the average across nine energy drinks, then fin fish, including the highest, yellow sea bream, down to tuna, one of the lowest. Then an average of chicken, beef, and pork.

Nori’s looking pretty good until you realize how light it is. To get one gram of taurine, you’d have to eat 10 servings a day, which is 40 sheets of nori, which, even if you could stomach it, would exceed your recommended iodine intake for the day. The easiest way to get a gram would be a quarter teaspoon of pure taurine powder, though one can of most energy drinks would do it. But then there’s the issue of added sugars or artificial sweeteners. Two daily servings of shellfish is a lot of shellfish, but certainly doable. Easier than eating eight daily servings of regular fish or 18 servings a day of land animals.

Here’s the cost comparison. This is where taurine powder really shines––at as little as a penny per day when bought in bulk, it’s 50 times cheaper than the next on the list. I used a combination of canned and fresh shellfish for this comparison. If you just did like canned clams, it would be more like $2.50 a day. In terms of saturated fat and cholesterol, shellfish are extremely lean, though the dietary guidelines recommends that dietary cholesterol consumption be as low as possible––90 is less than half an egg yolk.

Allergies are an issue for some. Shellfish is actually the most common type of food allergy in the United States, affecting about one in 35 people, though it may be as high as one in 10, depending on the method of diagnosis. Allergies to land-based meat are rare, unless you’ve been bitten by certain types of ticks.

Foodborne illness can also be a problem, particularly since shellfish, like oysters, are sometimes eaten raw. Usually, it’s just gastroenteritis, but it can sometimes develop into serious infections. Shellfish are filter-feeders, so they just pick up and concentrate pathogens from the environment. Most outbreaks are from human fecal pathogens from sewage that get in the water or the overboard disposal of feces from boats. I guess I never really thought about that, but like most crews from oyster-harvesting boats were just like tossing their waste overboard, and it came back to bite them.

How common is contamination of shellfish with foodborne human fecal viruses like norovirus, the most common cause of foodborne gastroenteritis? Nearly one in three samples of shellfish carries this kind of fecal contamination that can make us sick; yet, most consumers ignore the fact that shellfish usually come from places polluted by untreated human waste. Though fecal contamination is also found in 85 percent of retail ground beef and turkey, about half of chicken, and a third of pork. Thankfully, those meats are cooked, but still, contaminated poultry products probably cause the most food poisoning deaths, not shellfish.

Then, anytime you’re talking about the aquatic food chain, there are industrial pollutants. Pollution of the oceans is widespread and worsening, and pollutants include toxic heavy metals like mercury, microplastics, and industrial toxins like PCBs. Yes, we’ve been eating shellfish for more than a hundred thousand years, but that was before we so polluted our waterways. Shellfish pump and filter such large quantities of water in their feeding processes that they just tend to accumulate a lot of contaminants, like heavy metals. So, the consumption of contaminated shellfish can lead to neurological and developmental defects, reproductive and gastrointestinal disorders, and, in extreme cases, death. That seems a little extreme. They’re talking about contamination with algal toxins.

While filter-feeding, shellfish can ingest toxic algae, which can produce 100 different natural toxins. So, the shellfish can accumulate these toxins and pass them on to consumers. So, although we refer to them as shellfish toxins, they’re actually no more from the shellfish themselves than the human fecal viruses were.

When humans ingest different toxins accumulated in seafood, they may exhibit different poisoning syndromes. There’s paralytic shellfish poisoning, amnesic shellfish poisoning, neurotoxic shellfish poisoning, and diarrhetic shellfish poisoning.

Symptoms-wise, these can include abdominal pain, vomiting, diarrhea, severe headaches, confusion, agitation, sleepiness, memory loss, coma, loss of coordination, excessive scratching, tremors, heart arrhythmias, seizures, lethargy, inappetence—I’d never heard that word for loss of appetite––blindness, muscular twitches, behavioral changes, convulsions, and death, sometimes within hours. No antidotes are available. Sometimes, neuropsychological symptoms can last for years.

Some of the toxins may be carcinogenic, linked to a variety of different cancers. This may help explain cohort studies that found associations between colorectal cancer and the consumption of shellfish and shrimp. But, of course, it could also be the industrial pollutants.

The bad news is that toxic algae blooms are getting worse, thanks to climate change, but the good news is that the U.S. Food and Drug Administration has established a surveillance program to test for toxins; so, there are regulatory limits. Unfortunately, despite strong regulatory limits protecting people from acute poisoning, there is a growing body of evidence suggesting there are significant health consequences following repeated exposures to levels of an amnesic neurotoxin known as domoic acid, even when below current safety guidelines.

Those in the Pacific Northwest who eat a lot of razor clams, for example, with presumed safe levels, were found to be at risk for clinically significant memory problems. They are five to six times more likely to have problems with everyday memory, like having to check whether you actually did something, or forgetting to tell someone something important, or being forgetful day to day. The toxin doesn’t seem to be affected by cooking, and the “very high” levels of consumption were just more than 15 clams a month, so Washington State tells its residents to eat less than that. But to reach a gram a day of taurine, you’d have to eat 10 a day—300 a month. The bottom line is that even at levels deemed “safe” under current regulatory limits, algal toxins may not make mollusks the best source for taurine supplementation.

Finally today, the adverse effects of taurine on our microbiome and hydrogen sulfide production may be ameliorated by diets high in fiber and low in saturated fats.

In my last videos, I mentioned how the best choice might be to eat a healthy plant-based diet with supplemental taurine. But it’s possible that taking taurine—whether from bulk powder, supplements, energy drinks, or even shellfish—may only be safe in the context of a healthy plant-based diet.

In the remarkable study that launched this video series, taurine supplementation of lab animals increased their lifespan and/or healthspan. However, the impact of taurine dietary supplementation on the gut microbiome was not addressed. Oral administration of taurine results in the increase of taurine-conjugated bile acids––for example, quadrupling the percentage of taurocholic acid. That’s not good, because higher levels of taurocholic acid in humans are associated with a shorter lifespan.

For each standard deviation increase in a measure of taurocholate, which is just buffered taurocholic acid, the odds of achieving longevity in humans appears to decrease by almost 40 percent––a 37 percent lower chance of making it to age 80.

What happens is the metabolism of these taurine conjugated bile acids by our gut microbes generates the rotten egg gas, hydrogen sulfide, which doesn’t just give you smelly farts, but is a DNA-damaging compound. So, hydrogen sulfide could be a significant bacterial metabolite that initiates colon cancer. And that’s just the half of it. Taurocholic acid gets split into taurine and cholic acid. The taurine goes on to produce hydrogen sulfide, which is pro-inflammatory and could trigger DNA mutations, and the cholic acid gets turned into a toxic so-called secondary bile acid called deoxycholic acid, known as DCA, which also produces inflammation and can promote growing tumors. So, gut microbes can metabolize the taurocholic acid into hydrogen sulfide and DCA, which are genotoxins and tumor promoters, respectively, and could intensify aging symptoms in the host. Therefore, consumption of a diet low in taurine may contribute to the reduced frequency of cancer.

Taurine can promote the growth of taurine-metabolizing bacteria, Bilophila wadsworthia, which thrive on taurine. Those bacteria take the taurine and turn it into hydrogen sulfide, which is linked to a weaker colonic mucus barrier, inflammatory bowel disease, and colorectal cancer. So, it’s not just cancer; the increased taurocholate caused by taurine supplementation is associated with reduced lifespan in humans in the absence of any relation to risk to cardiovascular disease or cancer.

But the effects of hydrogen sulfide can be stopped. The cells that line our colon express protective enzymes that can detoxify hydrogen sulfide. How can we boost those enzymes? Butyrate boosts these detoxification enzymes, protecting our cells from the sulfide gas. Remember butyrate? That’s what our good gut bugs make from fiber. So, there’s this struggle between the sulfide made by the bad bugs in our gut versus the butyrate made by the good bugs in our gut. Hydrogen sulfide can cause hyperproliferation, a signal of potential colon cancer development, but it can be reversed if you drip on some butyrate, like you would get naturally by just eating a high-fiber diet.

That’s just half of the protection, though. The sulfur-containing amino acids, like taurine, and diets high in animal protein aren’t the only factors that select for the bad bacteria that create the toxic tumor-promoting secondary bile acids; there’s also the animal fat. When people were given taurine, like the half a gram three times a day I suggested in my last video, there was a marked increase in the proportion of taurine-conjugated bile acids––but what we care about is how many are actually excreted into our gut.

This is how it’s envisioned. On an animal-based diet, not only is there more taurine, leading to a higher ratio of taurine-conjugated bile acids, but also more bile secretion owing to the higher fat consumption.

High-fat diets are associated with increased taurine conjugation in humans, But not just any fat: specifically saturated fat. Consumption of a diet high in saturated fat, in this case butter fat, but not vegetable oil fat, promotes the expansion of the hydrogen sulfide-generating bad bacteria, and effects are mediated by milk-fat promoted taurine-conjugation bile acids. So, to counter any negative effects of excess taurine consumption, we should eat a high-fiber diet low in saturated fat––in other words, a diet centered around whole plant foods.

It reminds me of the whole vegetable nitrate strategy to boost athletic performance and slow muscle and artery aging, or slow aging period by reducing our resting metabolic rate. As I discuss in my book, How Not to Age, the nitrate strategy may only be safe in the context of a plant-based diet.

If you feed people an amine-rich diet––in other words a single meal a day with cod, salmon, shrimp, or pollack––along with the nitrate equivalent of half a cup (120 ml) of beet juice, you get a big jump in the amount of carcinogenic nitrosamines flowing through your system. You get a similar reaction combining the same amount of beet juice equivalents with poultry: chicken or turkey breasts. The nitrates turn into nitrites, which mix with the amines and amides concentrated in animal foods to form carcinogenic nitrosamines and nitrosamides, doubling levels within a week. This explains why having omnivores drink a single bottle of beet juice can lead to a significant rise in these carcinogenic compounds flowing through their system within 24 hours. But what are the inhibitors of this reaction for cancer prevention? Vitamin C, polyphenols, and other antioxidants found in plant foods. So, we can add some vitamin C to that beet juice, and there’s less of a problem. Just like a healthy plant-based diet may be necessary to take safe advantage of nitrate supplementation, a healthy plant-based diet may also be necessary to take safe advantage of any potential benefits of taurine supplementation.