Cancer-Causing Caramel Color

Caramel coloring may be the most widely consumed food coloring in the world.  Unfortunately, its manufacture can sometimes lead to the formation of a carcinogen called methylimidazole, which was identified as a cancer-causing chemical in 2007. For the purposes of its Proposition 65 labeling law, California set a daily limit at 29 micrograms a day. So, how much cancer might caramel-colored soft drinks be causing? We didn’t know…until now… My video Which has more Caramel Coloring Carcinogens: Coke or Pepsi? explores these questions and more.

Researchers tested 110 soft drink samples off store shelves in California and around the New York metropolitan area, including Connecticut and New Jersey. None of the carcinogen was found in Sprite, which is what you’d expect since Sprite isn’t caramel-colored brown. Among sodas that are, the highest levels were found in a Goya brand soda, while the lowest levels were in Coke products, which were about 20 times less than Pepsi products. Interestingly, California Pepsi was significantly less carcinogenic than New York Pepsi. “This supports the notion that [labeling laws like] Proposition 65…can incentivize manufacturers to reduce foodborne chemical risks…” To protect consumers around the rest of the country, federal regulations could be a valuable approach to reducing excess cancer risk—but how much cancer are we talking about?

Johns Hopkins researchers calculated the cancer burden, an estimate of the number of lifetime excess cancer cases associated with the consumption of the various beverages. So, at the average U.S. soda intake, with the average levels of carcinogens found, Pepsi may be causing thousands of cancer cases, especially non-California Pepsi products, which appear to be causing 20 times more cancer than Coke. Of course, there’s no need for any of them to have any these carcinogens at all “as caramel colorings serve only a cosmetic purpose [and] could be omitted from foods and beverages…” But we don’t have to wait for government regulation or corporate social responsibility; we can exercise personal responsibility and just stop drinking soda altogether.

Cutting out soda may reduce our risk of becoming obese and getting diabetes, getting fatty liver disease, suffering hip fractures, developing rheumatoid arthritis, developing chronic kidney disease, and maybe developing gout, as well.

In children, daily soda consumption may increase the odds of asthma five-fold and increase the risk of premature puberty in girls, raising the likelihood they start getting their periods before age 11 by as much as 47 percent.

If we look at the back of people’s eyes, we can measure the caliber of the arteries in their retina, and the narrower they are, the higher the risk of high blood pressure, diabetes, and heart disease. Researchers performed these kinds of measurements on thousands of 12-year-olds and asked them about their soda drinking habits. Their findings? Children who consume soft drinks daily have significantly narrower arteries. “The message to patients can no longer remain the simplistic mantra ‘eat less, exercise more.’” It matters what you eat. “[S]pecific dietary advice should be to significantly reduce the consumption of processed food and added sugar and to eat more whole foods.”


Prop 65 is lambasted by vested interests, but, as I mentioned, it may push manufacturers to make their products less carcinogenic. Other Prop 65 videos include:

For more background on caramel coloring, see my video Is Caramel Color Carcinogenic?.

There are other soda additives that are potentially toxic, too. See my three-part series on phosphates:

Other coloring agents are less than healthy. For more on this, see Artificial Food Colors and ADHD and Seeing Red No. 3: Coloring to Dye For.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

The Best Diet for Depression

Depression affects more than 150 million people worldwide, making it a leading cause of losing healthy years of life as a result of disability. By 2020, depression may be second only to heart disease as the leading cause of healthy years of life lost. Why is depression so common? Well it’s said, “Nothing in Biology makes sense except in the light of evolution.” Why would we evolve to get depressed?

Depression presents a baffling evolutionary puzzle. Despite its negative effects, it remains common and heritable, meaning a large part of the risk is passed through our genes. Presumably, there must be some kind of adaptive benefit or it would have been naturally selected against. Could depression be an evolutionary strategy to provide a defense against infection? Infection has been the leading cause of mortality throughout human history, making it a critical force in natural selection. Indeed, because of infections, our average life expectancy before the industrial period was only 25 years, and it was not uncommon for half of our children to die without reaching adulthood.

When we become infected, there is a surge of inflammation as our body mounts a counter-attack. Our body responds by feeling lousy, sick, weak, tired, and slow. We don’t want to socialize. The only thing we do want to do is sleep. These symptoms are similar to the ones we experience during depression and are great for fighting infection. Slowing down not only helps us conserve energy to put up a good fight; it also reduces social contact so we don’t infect others. We see this protective phenomenon in other social animals, like honeybees and mole rats, who feel compelled to crawl off and die alone to reduce the risk of infecting the rest of their community. Humans have even evolved to think poop and decaying flesh don’t smell particularly good to keep us safe from infection.

To explore the relationship between inflammation and mental health, we have to look back to 1887, when this connection was first noted by Dr. Julius Wagner-Jauregg, the only psychiatrist to ever win the Nobel Prize. What evidence have we accumulated in the past century that inflammation causes depression? We know that people who are depressed have raised inflammatory markers, such as C-reactive protein and that inflammatory illnesses are associated with greater rates of major depression. Indeed, we find depression in even more benign inflammatory conditions such as asthma and allergies. This is important as it suggests that the mood symptoms may be directly tied to the inflammation and are not simply the result of “feeling bad about having a terrible disease.”

We also know that you can induce depression by inducing inflammation. For example, when we give interferon for certain cancers or chronic infection, up to 50 percent of people go on to suffer major depression. Even just giving a vaccine can cause enough inflammation to trigger depressive symptoms. Taken together, these studies “are strongly suggestive of inflammation being a causative factor of mood symptoms.”

Can an anti-inflammatory diet help prevent depression? We didn’t know until researchers followed the diets of about 43,000 women without depression for approximately 12 years. Those who ate a more inflammatory diet, characterized by more soda, refined grains and meat, became depressed. “This finding suggests that chronic inflammation may underlie the association between diet and depression.”

Normally, we think of omega-3s as anti-inflammatory, but researchers found fish to be pro-inflammatory, associated with increased C-reactive protein levels. This is consistent with recent findings that omega-3s don’t seem to help with either depression or inflammation. As I discuss in my video Anti-Inflammatory Diet for Depression, the most anti-inflammatory diet is a plant-based diet, which is capable of cutting C-reactive protein levels by an impressive 30 percent within two weeks, perhaps because of the anti-inflammatory properties of the antioxidants found in plants. I talked about this in my Anti-Inflammatory Antioxidants video, but never explained why antioxidants are anti-inflammatory.

When free radicals cause oxidative damage, it may cause an autoimmune response in the body by changing the chemical structures of otherwise ubiquitous molecules to generate new structures that the body attacks as foreign. For example, when LDL cholesterol gets oxidized, our body creates antibodies against it that attack it. Likewise, clinical depression can be accompanied by increased oxidative stress and the autoimmune inflammatory responses it creates. Free radicals may thus lead to autoimmune inflammation.

Where else does inflammation in our diet come from? Endotoxins. It’s worth reviewing my videos on the subject—The Leaky Gut Theory of Why Animal Products Cause Inflammation, Dead Meat Bacteria Endotoxemia, and The Exogenous Endotoxin Theory—to see how the endotoxins in animal products can cause a burst of inflammation within hours of consumption. What does this burst do to our mood? Within a few hours of injecting endotoxin, inflammation shoots up, increasing feelings of depression and social disconnection.

Although previous research has demonstrated that inflammatory activity contributes to depressive symptoms, only recently did research show the effect of experimentally induced inflammation on anhedonia, the lack of reaction to pleasurable stimuli. In the study, subjects were injected with endotoxin. Within hours of the endotoxin hitting their bloodstreams, they began feeling depressed and had significant activity reductions in the reward center of the brain. The subjects, for example, were less excited about winning money playing video games. But as I discuss in my Plant-Based Diets for Improved Mood and Productivity and Antioxidants and Depression videos, we may be able to treat or even prevent depression by eliminating animal products and eating antioxidant-rich diets.


If you’re as much of a sucker for evolutionary biology theory as I am, you can learn more about it by checking out my High Blood Pressure May Be a Choice, The Problem with the Paleo Diet Argument and Why Do We Age? videos. 

I have several videos on inflammation, including: 

And in Biblical Daniel Fast Put to the Test, I discuss a study that shows a dramatic decrease in inflammation within weeks on a plant-based diet.

For more information on the effect diet can have on mental health, check out:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: