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By Dr. Mercola
More than 1,660,290 new cancer cases are projected to be diagnosed in the US this year, and an estimated 580,350 Americans will die from the disease.1 Another 600,000 Americans die of heart disease each year.2 At present, heart disease is the leading cause of death among both sexes.
Despite massive technological advances over the past half-century, Western medicine is still at a loss for how to rein in the prevalence of these top two killers.
It’s become increasingly clear that many of the conventional strategies, from diagnosis to treatment, are riddled with flawed assumptions and approaches that, in many cases, do more harm than good.
What’s worse, virtually none of the conventional strategies actually address the root cause of the problem, a flawed diet high in sugars and processed foods.
In fact, conventional dietary recommendations for the prevention of heart disease are diametrically opposed to what you actually need for optimal heart health! For over 60 years, saturated fats have been blamed for heart disease, resulting in the promulgation of a dangerous low-fat, high-sugar diet.
In reality, a diet that promotes health is high in healthful fats and very, very low in sugar and non-vegetable carbohydrates... Research coming out of some of America’s most respected institutions now confirms that sugar is a primary dietary factor driving chronic disease development.
Sugar, and fructose in particular, has been implicated as a culprit in the development of both heart disease and cancer, and having this information puts you in the driver’s seat when it comes to prevention.
How Much Sugar Is in Your Diet?
Ever since I started this Web site back in 1997, I’ve been warning about the dangers of high sugar consumption. It’s important to realize that even if you don’t add sugar to your foods, hidden sugar, typically in the form of high fructose corn syrup (HFCS), is in virtually all processed foods, from yogurts and sauces to breads and sodas.
Many favorite staples are also grain-based, such as bagels, pancakes, and breakfast cereals. All those grains are also quickly turned into sugar in your body, adding to your sugar burden.
Clinical trials have shown that those who consume HFCS tend to develop higher risk factors for cardiovascular disease within as little as two weeks, so if I had to pick out the worst culprit among sugars, it would be fructose.
Other studies indicate that if you limit your sugar, no matter what form you get it in, you effectively decrease your chances of developing cancer—including breast and colon cancers.
Soda Drinkers Have Increased Cancer Risk
According to recent research,3, 4 older women who drink a lot of soda or other sugary beverages may be at significantly increased risk for endometrial cancer—an estrogen-dependent type of cancer that affects the lining of a woman’s uterus.
The study included data for more than 23,000 postmenopausal women who were followed for 14 years.
Women who had the highest intake of sugary beverages had a whopping 78 percent higher risk for endometrial cancer, and the risk appeared to be dose dependent; rising right along with consumption. Study author Maki Inoue-Choi was not surprised by the results, and neither am I.
“Other studies have shown increasing consumption of sugar-sweetened beverages has paralleled the increase in obesity. Obese women tend to have higher levels of estrogens and insulin than women of normal weight, [and] increased levels of estrogens and insulin are established risk factors for endometrial cancer,” she said.5
Previous research has also shown that dietary fructose can promote cancer growth in a number of different ways, including:
- Altered cellular metabolism
- Increased reactive oxygen species (free radicals)
- DNA damage
Fructose Promotes Cancer Cell Proliferation
Studies have shown that different sugars are metabolized using different metabolic pathways, and this is of MAJOR consequence when it comes to feeding cancer and making it proliferate. Three years ago, researchers published findings showing that fructose is readily used by cancer cells to increase their proliferation.6 Cancer cells did not respond to glucose in the same manner.
In this case, the cancer cells used were pancreatic cancer, which is typically regarded as the most deadly and universally rapid-killing form of cancer. According to the authors:
“Traditionally, glucose and fructose have been considered as interchangeable monosaccharide substrates that are similarly metabolized, and little attention has been given to sugars other than glucose. However, fructose intake has increased dramatically in recent decades and cellular uptake of glucose and fructose uses distinct transporters.
Here, we report that fructose provides an alternative substrate to induce pancreatic cancer cell proliferation. Importantly, fructose and glucose metabolism are quite different; in comparison with glucose, fructose... is preferentially metabolized via the nonoxidative pentose phosphate pathway to synthesize nucleic acids and increase uric acid production.
These findings show that cancer cells can readily metabolize fructose to increase proliferation. They have major significance for cancer patients given dietary refined fructose consumption, and indicate that efforts to reduce refined fructose intake or inhibit fructose-mediated actions may disrupt cancer growth.” [Emphasis mine]
The study confirms the old adage that sugar feeds cancer because they found that tumor cells do thrive on sugar (glucose). However, the cells used fructose for cell division, speeding up the growth and spread of the cancer. This difference is clearly of major consequence, and should be carefully considered by anyone who is currently undergoing cancer treatment or seeking to prevent cancer.
This does not mean you should avoid fruits, the benefits of most fruits outweigh any concerns to fructose. I would suggest to not juice your fruits and to eat them whole, and also realize we have bred many of these fruits to a very high level of fructose. Fruits today are many times sweeter than they were historically, and should be consumed in moderation. The real problem is the high fructose corn syrup that is added to practically every processed food and drink you see.
Remember: Exercise Is Another Potent Ally Against Cancer and Heart Disease
Controlling your blood-glucose and insulin levels—through diet, along with a comprehensive exercise program—can be one of the most crucial components to a cancer recovery program. These factors are also crucial in order to prevent cancer in the first place. Diet and exercise—particularly high intensity interval training—are also the dynamic duo that will help you stave off heart disease.
In fact, a recent meta-analysis that reviewed 305 randomized controlled trials found no statistically detectable differences between exercise and medications for heart disease, including statins and beta blockers. (Previous research has also shown that exercise alone can reduce your risk of cardiovascular disease by a factor of three,7 which isn’t too shabby.) Exercise is in fact so potent, the researchers suggested that drug companies ought to be required to include it for comparison when conducting clinical trials for new drugs. As reported by Bloomberg:8
“The analysis adds to evidence showing the benefit of non-medical approaches to disease through behavior and lifestyle changes... ‘In cases where drug options provide only modest benefit, patients deserve to understand the relative impact that physical activity might have on their condition,’ Naci and Ioannidis said in the published paper. In the meantime, 'exercise interventions should therefore be considered as a viable alternative to, or, alongside, drug therapy.'”
In a nutshell, being a healthy weight and exercising regularly creates a healthy feedback loop that optimizes and helps maintain insulin and leptin receptor sensitivity. And, as I’ve mentioned before, insulin and leptin resistance—primarily driven by excessive consumption of refined sugar and grains along with lack of exercise—are the underlying factors of nearly all chronic disease.
Connecting the Dots: Fructose—Uric Acid—Cancer and Chronic Disease Risk
The theory that sugar feeds cancer was actually born nearly 80 years ago. Shockingly, most conventional cancer programs STILL do not adequately address diet and the need to avoid sugars. The 1931 Nobel laureate in medicine, German Otto Warburg, Ph.D., first discovered that cancer cells have a fundamentally different energy metabolism compared to healthy cells. Malignant tumors tend to use a process where glucose is used as a fuel by the cancer cells, creating lactic acid as a byproduct.9
The large amount of lactic acid produced by this fermentation of glucose from cancer cells is then transported to your liver. This conversion of glucose to lactic acid generates a lower, more acidic pH in cancerous tissues as well as overall physical fatigue from lactic acid buildup.10, 11
This is a very inefficient pathway for energy metabolism, which extracts only about five percent of the available energy in your food supply. In simplistic terms, the cancer is "wasting" energy, which leads you to become both tired and undernourished, and as the vicious cycle continues, will lead to the body wasting so many cancer patients experience. Additionally, carbohydrates from glucose and sucrose significantly decrease the capacity of neutrophils to do their job. Neutrophils are a type of white blood cell that helps cells to envelop and destroy invaders, such as cancer.
While all forms of sugar are detrimental to health in general and promote cancer, but in slightly different ways and to a different extent, fructose clearly seems to be one of the overall most harmful. As mentioned above, fructose metabolism leads to increased uric acid production along with cancer cell proliferation.12 Again, ONLY fructose (not glucose) drives up your uric acid levels.
Now, the connection between fructose, uric acid, and insulin resistance is so clear that your uric acid level can actually be used as a marker for toxicity from fructose. What this means is that if your uric acid levels are high, you’re at increased risk of all the health hazards associated with fructose consumption—including both heart disease and cancer. Subsequently, you’d be well advised to reduce your fructose intake. For more information about this, please see my previous interview with Dr. Richard Johnson, who is an expert on this topic. Two key recommendations however are:
- Keep your uric acid level below 4 mg/dl for men and 3.5 mg/dl for women, and
- As a standard recommendation, I strongly advise keeping your TOTAL fructose consumption below 25 grams per day
Reeling in Your Fructose Consumption May Be the Most Important Lifestyle Change You Can Make
Dr. Johnson has written one of the best books on the market on the health dangers of fructose, called The Sugar Fix, which explains how fructose causes high blood pressure, heart disease, obesity, diabetes, and kidney disease. It’s also safe to say that many cancers are also on the list of diseases that are directly linked to excessive fructose consumption. In addition to the studies already mentioned, fructose has also been found to promote metastasis in breast cancer,13 and shows genotoxic effects on the colon in animal research.14
Fructose also promotes a condition called intracranial atherosclerosis15—a narrowing and hardening of the arteries in your skull—and contrary to popular belief, it is the sugar/fructose in your diet that increases your risk for heart disease, NOT saturated animal fats.
At the basic dietary level, the prevention strategies for heart disease and cancer are identical. First and foremost, you need to address your insulin and leptin resistance, which is the result of eating a diet too high in sugars and grains—again, not fat, with the exception of trans fats from partially hydrogenated vegetable oils, which have been linked to increased heart disease risk, even in small amounts. To safely and effectively reverse insulin and leptin resistance, you need to:
- Avoid sugar, processed fructose, grains if you are insulin and leptin resistant, and processed foods
- Eat a healthful diet of whole foods, ideally organic, and replace the grain carbs with:
- Large amounts of vegetables
- Low-to-moderate amount of high-quality protein (think organically raised, pastured animals)
- As much high-quality healthful fat as you want (saturated and monosaturated from animal and tropical oil sources). Most people actually need upwards of 50-85 percent fats in their diet for optimal health—a far cry from the 10 percent currently recommended.
Restricting Fructose Consumption Is Crucial Part of a Healthy Lifestyle
Whether we’re talking about heart disease or cancer, reducing (or preferably eliminating) fructose and other added sugars, as well as limiting grain carbohydrates from your diet is a primary strategy on my list if you have insulin and leptin resistance. This dietary modification should also be part of your comprehensive treatment plan if you’ve been diagnosed with either cancer or heart disease.
Understand that excessive fructose consumption leads to insulin resistance, and insulin resistance appears to be the root of many if not most chronic disease, including heart disease and cancer. So far, scientific studies have linked excessive fructose consumption to about 78 different diseases and health problems.16
By severely reducing your intake of fructose and carbs in your diet, you help stave off any potential cancer growth, and “starve” any tumors you currently have. It also bolsters your overall immune function, because sugar decreases the function of your immune system almost immediately.