toxic brownie

Side Effects of Chocolate Might Include Cancer

Is maca powder a superfood? With an ORAC value of 6,100 it doesn’t qualify as a super antioxidant, that’s for sure.

You can get 800% more antioxidants with unsweetened raw cacao. Its ORAC is 55,653. That’s half as much as freeze-dried acai… one of nature’s most concentrated sources.

Is it possible something so healthy might actually be dangerous?

Sure, you can easily come up with a list of 10 reasons why chocolate is bad for you.

Calories, fat, sugar, caffeine, heartburn, and being a headache trigger are some of the more obvious drawbacks. But most of those are not from the cocoa, but rather the form it’s in… a little powder mixed with a lot of unhealthy sugar and dairy.

Did you know you could eat an entire measuring cup of the pure cocoa powder and it would only be 196 calories? With that comes 17 grams of protein, zero cholesterol, and you would only hit 18% of your daily value for fat intake.

Yep those numbers are for real. Check the USDA National Nutrient Database if you don’t believe them (1).

How does chocolate affect your body?

Naked and unsweetened, it’s an ingredient which is nutritious. Since the powder contains very little cocoa butter, it’s a low calorie and low fat choice, relatively speaking. Your body will be nourished and your brain will be stimulated by the high amounts of caffeine and theobromine, which is another natural pick-me-up.

What is theobromine?

theobromine molecule and chemical formulaThis bitter tasting alkaloid is found in cocoa. When it comes to mental alertness, it is a stimulant estimated to have about 10% the potency of caffeine. However theobromine is more potent when it comes to cardiac stimulation. Preliminary research suggests it has a side effect of raising your heart rate and at the same time, a potential benefit of lowering your systolic blood pressure. As with caffeine, high dosages of theobromine may be dangerous. (2)

Other natural sources of theobromine include teas made from Camellia sinensis. All caffeinated teas – black, white, and green tea – are made using this plant.

Among the different types, matcha green tea contains the most theobromine, but it’s still significantly less than how much there is in chocolate.

According to the USDA National Nutrient Database:

  • 1712 mg is in 1 cup of unsweetened baking chocolate squares (3).
  • 5 mg is in 1 cup of brewed black tea (4).

There is no theobromine in coffee beans.

Chocolate is by far the biggest food source of theobromine. Is there a dark side to this unique alkaloid?

The effects of eating chocolate before bed might give you insomnia. Especially since the half-life of theobromine is long – around 7 hours. For dogs, it’s a staggering 17 hours (5). That’s a big problem since it’s poisonous to them.

But the worst thing it can do might be something far more sinister.

Cancer causes 101

What is cancer? It’s a cell mutation gone wild.

Your body experiences countless cell mutations everyday – that’s where there is a permanent alteration in the DNA sequence of a cell.

A mutation may not be dangerous now, or even twenty years from now, but over your life the damage can be cumulative.

Each time the cell replicates itself, it will pass along the prior mutation. That new cell can also experience mutations.

Mutations on top of mutations. Not good.

The effects of most are benign or immeasurable. But you never know when a mutation (whether a single or a cumulative) will lead to a dangerous outcome… cancerous growth.

how cancer cells multiply after mutation

Cancer is when the instructions encoded in the DNA give the wrong message – they tell the cell to keep replicating and grow out of control.

Often times the first stages of this are stopped by the body… the mutated cells get destroyed before they become a big problem. But it just takes one of these to slip past your body’s defenses, reaching a state of growth which is too progressed for your body to stop.

Cancer often happens during a subsequent DNA mutation – a mutated cell that mutates again, then again, and so forth. That’s why DNA damage you experienced during your childhood could cause brain cancer when you’re 40.

It’s also why your risk of cancer goes up exponentially as you get older.

In a nutshell, most cell mutations are not a cancer risk, but they have the potential to be.

DNA mutation graphicThat’s why you want to minimize your exposure to things which mutate your DNA.

Cigarette smoke, UV light, and certain chemicals are obvious examples. They’re called mutagens, because they can mutate the alleles of your DNA.

There are many not so obvious examples of mutagens in your daily life that you’re totally oblivious of.

Buying organic is actually one of the least important dietary decisions in your life. Sure, some pesticides may be suspected carcinogens, but how about the confirmed carcinogens you already eat daily?

Certain types of polycyclic aromatic hydrocarbons (PAHs) found in cooked meat – particularly when the meat is grilled, fried, and smoked – are not only mutagenic, but also carcinogenic.

Benzo(a)pyrene has the absolute worst ranking; it’s a Group 1 carcinogen (6).

Carcinogen is the label given to a mutagen which has been found to cause cancer. In other words, the types of mutations it causes have been conclusively linked to higher rates of cancer.

To get the official carcinogenic classification is not easy. Many extensive studies are needed. Decades’ worth of research coming from numerous sources are needed to conclusively prove an allegation that something causes cancer at a statistically significant rate.

Obviously, there’s just not the time, money, and resources to thoroughly investigate every mutagen for that possibility.

Not to mention, if you’re in an industry which financially benefits from selling something that might be bad for you, why would you want to produce evidence of that? Sweeping the issue under the rug is preferable, from a business perspective.

One such suspected mutagen which has very little research behind it is theobromine. That’s right, this stimulant – which is almost completely unique to chocolate – has demonstrated mutagenicity in laboratory research.

Old news, unanswered questions

scientist conducting experiment in Petri dishDuring checkout at the supermarket, Mutation Research isn’t the type of magazine you will find next to US Weekly. It’s a scientific journal which his put out by Elsevier, a leader in the industry.

Way back in 1975, that journal published a piece of research titled “Theobromine and Theophylline” (7).

One way to preliminarily test if something is mutagenic is to use cultured cells. That’s where you basically put living cells in a Petri dish and observe what happens to them when they come in contact with the compound in question.

Here’s what this 1975 research piece reported:

“Chromosome abnormalities are caused by both theobromine and theophylline in plant cells and in mammalian cells in culture, and both have anti-mitotic activity.”

Anti-mitotic means interfering with the division of cells.

E. coli is quite different than mammals, such as a human, but it’s often used as a preliminary test in determining mutagenicity. Since they have short life spans, it’s easier for scientists to monitor their entire life and even subsequent generations, all within a brief period of time.

Here’s what that paper had to say about E. coli being exposed to theobromine and/or theophylline:

“…they are fairly potent mutagens in Escherichia coli and other lower organisms.”

That was over 40 years ago. Extensive amounts of research on the effects of eating chocolate everyday, during pregnancy, and so forth must have been done since then to evaluate this issue, right?

Not really.

1984, a study was published about rats which were given high oral dosages of theobromine from cocoa and it was said (8):

“…results indicated no induction of dominant lethal mutations or adverse effects on pregnancy rate after TBR [theobromine] doses equivalent to 25-225 times the maximum human consumption level.”

But that was just a 10 week study and the pregnant females were killed merely 13 days after mating in order to be evaluated.

In 1987, you had the journal Food & Chemical Toxicology publishing data on the mutagenicity of theobromine and implying it’s safe (9):

“In spite of some positive responses, these analyses did not predict for theobromine a potential for causing cancer by virtue of a genotoxic mechanism.”

But that was based on lab experiments.

You have a 2010 study out of Poland which suggests that theobromine may actually help prevent DNA damage by acting as a “binding agent” to acridine orange, which is a known mutagen (10).

However that too was only lab research.

Is chocolate safe?

The International Agency for Research on Cancer (IARC) is part of the World Health Organization. Since it’s intergovernmental, this agency is considered to be the number one authority on classifying carcinogens.

They conducted an in-depth review as to whether or not cocoa is safe due to this compound.

Unfortunately, that last review was done some 20 years ago, in 90’s. They weren’t even doing the studies themselves, just analyzing those done by others.

The below table are the studies they looked it (11). Even if they reviewed the scientific data as of today, that list wouldn’t change much. Not much has been published during the last decade or two relating to this.

observed side effects of theobromine from chocolate

In the column they are marked either positive (genetic side effects observed), negative, or inconclusive.

We’ve red lined those marked as positive.

Of particular worry (for us at least) are those for chromosomal aberrations in human lymphocytes, which is a type of white blood cell.

All of the above tests were done on bacteria, hamsters, mice, rats and cultured cells.

Almost no human research on mutagenicity is cited by the IARC. The best they have are a couple tests on cultured human white blood cells… and those aren’t exactly what you would call encouraging news for chocolate lovers.

What’s the verdict?

Before we get to the final conclusion of the IARC, here are some statements in their report that might raise eyebrows…

“Oral administration of high doses of theobromine to rats caused severe testicular atrophy, which was largely irreversible.”

If that’s one of the health effects of eating chocolate, then just about any man would be terrified of candy bars for the rest of his life!

Following that scary sentence, they talked about how lower amounts given for extended periods of time had “no significant adverse effects” on the rat testicles. Other mammals like hamsters, mice, and dogs were said to be “less sensitive or were resistant” to that happening.

Even with that happening in rats, it was said that “no adverse reproductive effect” was seen in them after being studied for three generations.

Even if you ate carob chips and dark chocolate bars all day long, you wouldn’t  be consuming anywhere close to the high dosage amount in rats, which had the side effect of shrunken balls.

Plus since others mammals like dogs were more immune to experiencing that, it sounds like this would be a very unlikely side effect in humans.

But what about being a mutagen? Does dark chocolate cause cancer?

Here’s some of the more negative genetic observations the IARC made note of:

“In human cells in vitro, theobromine induced sister chromatid exchange and chromosomal breaks.”

“In cultured mammalian cells, it induced gene mutations and sister chromatid exchange but not chromosomal aberrations or cell transformation.”

IARC cancer ratingsFor those bad side effects, they countered with the other studies suggesting the theobromine in chocolate is safe. In section 5.5 (Evaluation) they state:

“There is inadequate evidence for the carcinogenicity in humans of theobromine.”

“There are no data on the carcinogenicity of theobromine in experimental animals.”

And in the overall evaluation they report:

“Theobromine is not classifiable as to its carcinogenicity to humans (Group 3)”

There’s your answer. You can’t say chocolate milk can cause cancer, or any other form of it. Just like the IARC says, there is “inadequate evidence for the carcinogenicity in humans.” But has this concern been studied enough?

Not in our opinion.

Setting aside our own selfish health concerns for a moment, how about the well-being of others… like babies?

Forty years ago it was reported that nursing mothers will pass theobromine on in their breast milk (12):

“If a mother ate a 4-ounce chocolate bar every 6 hours and the infant nursed when the theobromine concentration in milk was at its peak, the infant could ingest about 10 mg of theobromine per day.”

That was only after the mothers ingested milk chocolate, which is much less concentrated than dark or pure raw cocoa, which of course are the superfood forms used these days.

Is chocolate dangerous?

chocolate trufflesFor dogs and cats, you probably already know it’s dangerous. For humans, previously your only concern may have been expired or out of date chocolate. The bad things about chocolate affecting cells is a whole other concern. What should you make of it?

We feel comfortable enough to continue eating chocolate and here’s why…

In the human cultured cells, it required higher dosages of theobromine to produce the effect of sister chromatid exchanges (that’s where genetic material between two identical areas switches). Plus it was cultured cells, without the presence of a metabolic system.

For these and other reasons which are a bit too technical to explain here, there might have been false positives.

More concerning to us were the chromosomal breaks, but again, there isn’t enough data to evaluate that one way or another. This is why more extensive research is desperately needed.

Might cancer be a side effect? The chance of that seems greater for lower life forms than for humans. For us, the known health benefits of chocolate seem to outweigh the theobromine concern, at least based on the pros and cons we know as of today.

We actually think it’s bad to eat chocolate everyday for a totally different reason… the potential for cadmium and lead poisoning.

During the past few years this concern has hit mainstream media, because multiple groups have conducted laboratory testing and reported disturbing results. The non-profit As You Sow had tested 70 chocolate products and found that 45 contained lead and/or cadmium above California’s Prop 65 threshold (13).

Those which reportedly failed their test included high end organic dark chocolate brands like Equal Exchange, Theo, and Endangered Species, as well as lower cost brands like Hershey’s, Trader Joe’s, Whole Foods brand, See’s Candies, and Ghirardelli.

Again, those numbers were not alarming enough for us to forgo chocolate altogether, but we have cut back on our daily consumption of raw cacao powder. The powders seem to test worse than the nibs and bars. Some have speculated if the machinery used for processing cocoa beans might be a reason for that.

Caffe Sanora coffee
Our preferred morning cup of Joe.

If you are going to cut things out of your diet because of mutagenicity concerns, then there are other foods and drinks we would express much greater concern over versus chocolate.

Avocadoes might be bad for you.

Then there is something you probably drink everyday, which is coffee. It contains potent amounts of a known carcinogen.

We still drink it daily, but we opt for the lowest acrylamide coffee brands and types. You should do the same.