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:

We Are Human-Microbe Superorganisms

The microbiome revolution in medicine is beginning to uncover the underappreciated role our healthy gut bacteria play in nutrition and health.

Recently, it has become apparent that our DNA “does not tell the whole story of our individuality and other factors, environmental factors, play an important role in human health and disease,” researchers concluded. We can thank two revolutions in biology for this revelation. First, there was epigenetics, where diet and lifestyle changes have been shown to turn genes on and off. Second was our unfolding understanding of our microbiome—that is, how changes in our gut flora “appear to impact greatly on human biology.”

“Until relatively recently, the colon was viewed as a retention tank for waste,” and water absorption was its big biological function. The problem was it was hard to get in there, and we weren’t able to grow most of the bugs in a lab. As many as 99% of all microbes fail to grow under standard laboratory conditions. How do you study something you can’t study? Well, now we have fancy genetic techniques.

It took 13 years to sequence the DNA of the first bacteria ever. These days, the same feat might only take two hours. What we’ve learned is that we can each be thought of as a super-organism, a kind of “human-

microbe hybrid,” as one researcher called it. We have trillions of bacteria living inside us. One commentator went as far as to say, “We are all bacteria,” which is a provocative way of acknowledging there are more bacterial cells and genes in our own body than there are human cells and genes, and most of those bacteria live in our gut.

All animals and plants appear to establish symbiotic relationships with microorganisms and, in us, our gut flora can be considered like a “forgotten organ.” Studies indicate that the health-promoting effects of our good bacteria include boosting our immune system, improving digestion and absorption, making vitamins, inhibiting the growth of potential pathogens, and keeping us from feeling bloated. But, should bad bacteria take roost, they can release carcinogens, putrefy protein in our gut, produce toxins, mess up our bowel function, and cause infections.

Researchers are still in the process of figuring out which bacteria are which. There are more than a thousand different types of bacteria that take up residence in the human colon. In my video, Microbiome: The Inside Story, I include a diagram from a typical study of gut flora that gives a sense of the complexity. It comes from what happens to be the largest such study done on the elderly and shows that the frailest tend to harbor similar bugs. The study goes on to suggest that it may be the lousy diet in nursing homes that’s causing this shift, which may play a role in ill health as we grow older.

Based on studying what comes out of fraternal versus identical twins, those who eat different habitual diets, and stools from around the world, “[i]t has become evident that diet has a dominant role on the [bacteria in our colon] and that diet-driven changes in it occur within days to weeks,” the research found. Change your diet, change your gut flora.

“The hope of impacting health through diet may be one of the oldest concepts in medicine; however, only in recent years has our understanding of human physiology grown to the point where we can begin to understand how individual dietary components affect specific illnesses,” researchers explain, through our gut bacteria. Milk fat on that piece of pizza, for example, may feed the bacteria that produces the rotten egg gas hydrogen sulfide, and has experimentally been associated with colitis (inflammatory bowel disease). Fiber, on the other hand, feeds our good bacteria and decreases inflammation in the colon. Both choline, which is found in eggs, seafood, and poultry, and carnitine, which is found in red meat, can be turned into trimethylamine oxide and contribute to heart disease and perhaps fatty liver disease. Excess iron may also muck with our good bacteria and contribute to inflammation, as well.


The good news, researchers found, is that “[s]pecific dietary interventions offer exciting potential for nontoxic, physiologic ways to alter [gut microbiology] and metabolism to benefit the natural history of many intestinal and systemic disorders.”

 If you’re interested in more information about friendly flora, I suggest watching the following:

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:

Foods to Eat to Help Prevent Diabetes

Why is meat consumption a risk factor for diabetes? Why does there appear to be a stepwise reduction in diabetes rates as meat consumption drops? Instead of avoiding something in meat, it may be that people are getting something protective from plants. Free radicals may be an important trigger for insulin resistance, and antioxidants in plant foods may help. Put people on a plant-based diet, and their antioxidant enzymes shoot up. So not only do plants provide antioxidants, but may boost our own anti-endogenous antioxidant defenses, whereas, on the conventional diabetic diet, they get worse.

In my video, How May Plants Protect Against Diabetes, I discuss how there are phytonutrients in plant foods that may help lower chronic disease prevalence by acting as antioxidants and anti-cancer agents, and by lowering cholesterol and blood sugar. Some, we’re now theorizing, may even be lipotropes, which have the capacity to hasten the removal of fat from our liver and other organs, counteracting the inflammatory cascade believed to be directly initiated by saturated-fat-containing foods. Fat in the bloodstream—from the fat on our bodies or the fat we eat—not only causes insulin resistance, but also produces a low-grade inflammation that can contribute to heart disease and non-alcoholic fatty liver disease.

Fiber may also decrease insulin resistance. One of the ways it may do so is by helping to rid the body of excess estrogen. There is strong evidence for a direct role of estrogens in the cause of diabetes, and it’s been demonstrated that certain gut bacteria can produce estrogens in our colon. High-fat, low-fiber diets appear to stimulate the metabolic activity of these estrogen-producing intestinal bacteria. This is a problem for men, too. Obesity is associated with low testosterone levels and marked elevations of estrogens produced not only by fat cells but also by some of the bacteria in our gut. Our intestinal bacteria may produce these so-called diabetogens (diabetes-causing compounds) from the fats we eat. By eating lots of fiber, though, we can flush this excess estrogen out of our bodies.

Vegetarian women, for example, excrete two to three times more estrogens in their stools than omnivorous women, which may be why omnivorous women have 50% higher estrogen blood levels. These differences in estrogen metabolism may help explain the lower incidence of diabetes in those eating more plant-based diets, as well as the lower incidence of breast cancer in vegetarian women, who get rid of twice as much estrogen because they get rid of twice as much daily waste in general.

Either way, “[m]eat consumption is consistently associated with diabetes risk. Dietary habits are readily modifiable, but individuals and clinicians will consider dietary changes only if they are aware of the potential benefits of doing so.” The identification of meat consumption as a risk factor for diabetes provides helpful guidance that sets the stage for beneficial behavioral changes. Meat consumption is something doctors can easily ask about, and, once identified, at-risk individuals can then be encouraged to familiarize themselves with meatless options.


Plant foods may also protect against diabetes by replacing animal foods. Learn more with my Why Is Meat a Risk Factor for Diabetes? video.

What if your entire diet was filled with plants? See Plant-Based Diets and Diabetes. Find out which plants may be particularly protective with these videos: Amla Versus Diabetes, Flaxseed vs. Diabetes, and Diabetics Should Take Their Pulses.

Unfortunately, cinnamon has fallen out of favor. See my Update on Cinnamon for Blood Sugar Control.

I also have an ever-growing series on the science behind type 2 diabetes:

For more on the estrogen connection, see Relieving Yourself of Excess Estrogen and Breast Cancer and Constipation.

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: