By Dr. Mercola
Obesity is associated with a significant number of health problems, including insulin resistance, cancer, and others, and now researchers may have uncovered a reason why. While most of your tissues and organs age at the same rate, certain factors may cause aging to accelerate.
For this reason, you may be "older" than your chronological age indicates, or certain organs may be more aged than others – a measure known as "epigenetic age." One such factor linked to an acceleration of epigenetic aging is obesity, particularly in your liver.
Obesity Accelerates Aging in Your Liver
If you're obese, new research found, your liver may be aging faster than the rest of your body, putting you at risk of chronic disease. For each increase in 10 body mass index (BMI) units, the epigenetic age of the liver grew by 3.3 years.1
Steve Horvath, a professor of human genetics and biostatistics at the University of California, Los Angeles School of Public Health, explained:2
"Assume there is a man who is 5-foot-8 and weighs 130 pounds. This slender man would have a body mass index of 20… Compare him to a man of the same age and height who weighs 230 pounds. The liver of this obese man -- who has a BMI of 35 -- would probably be five years older than that of the slender man."
Obesity surgery had no apparent effect on the age of the liver, even when it resulted in rapid weight loss. Further, obesity did not appear to impact aging in fat, muscle, or blood – only the liver.
Hovath and colleagues were able to measure the precise epigenetic age of liver samples using an "epigenetic clock" that Hovath developed. It's based on DNA methylation—a process by which a methyl group (one carbon atom attached to three hydrogen atoms) is added to part of a DNA molecule.
DNA methylation is a crucial part of normal cell function, allowing cells to "remember who they are and where they have been" and is important in regulating gene expression.
DNA methylation also suppresses the genes for things you don't want, such as viral and other disease-related genes, and abnormal DNA methylation plays a critical role in the development of nearly all types of cancer.
The Fructose Connection: How It Causes Both Obesity and Liver Damage
The reason obesity might accelerate aging in your liver could have to do with an underlying cause of both weight gain and liver damage: fructose. You may already be aware that fructose – the sugar found in everything from high fructose corn syrup and fruit juice to agave syrup and honey – is harmful when consumed in excess.
This is precisely what most Americans do. However, you may be surprised to learn that fructose is, in many ways, very similar to alcohol in the damage that it can do to your body… and your liver.
Unlike glucose, which can be used by virtually every cell in your body, fructose can only be metabolized by your liver, because your liver is the only organ that has the transporter for it.3
Since nearly all fructose gets shuttled to your liver, and, if you eat a typical Western-style diet, you consume high amounts of it, fructose ends up taxing and damaging your liver in the same way alcohol and other toxins do. In fact, fructose is virtually identical to alcohol with regard to the metabolic havoc it wreaks.
According to Dr. Lustig, Professor of Pediatrics in the Division of Endocrinology at the University of California, fructose is a "chronic, dose-dependent liver toxin." And just like alcohol, fructose is metabolized directly into fat – not cellular energy, like glucose.
His findings were published in the Journal of the Academy of Nutrition and Dietetics,4 where Dr. Lustig explained the three similarities between fructose and its fermentation byproduct, ethanol (alcohol):
- Your liver's metabolism of fructose is similar to alcohol, as they both serve as substrates for converting dietary carbohydrate into fat, which promotes insulin resistance, dyslipidemia (abnormal fat levels in the bloodstream), and fatty liver
- Fructose undergoes the Maillard reaction with proteins, leading to the formation of superoxide free radicals that can result in liver inflammation similar to acetaldehyde, an intermediary metabolite of ethanol
- By "stimulating the 'hedonic pathway' of the brain both directly and indirectly," Dr. Lustig noted, "fructose creates habituation, and possibly dependence; also paralleling ethanol"
Fructose Is a Leading Cause of the Obesity Epidemic
Fructose not only damages your liver; it's also a leading cause fueling the obesity epidemic in both adults and children. In order for you to significantly gain weight, you must first become leptin resistant. Leptin is a hormone that helps you regulate your appetite. When your leptin levels rise, it signals your body that you're full, so you'll stop eating.
However, as you become increasingly resistant to the effects of leptin, you end up eating more. Many people who are overweight also have an impairment in their body's ability to oxidize fat, which leads to a low-energy state. The question then is: what drives this basic process? Why do you become leptin resistant in the first place?
Dr. Richard Johnson is the head of nephrology at the University of Colorado and is actively engaged in clinical research. Over the past 25 years, much of his research (which is funded by the National Institutes of Health) has focused on fructose and obesity-related diseases.
His hypothesis is that, rather than being driven by eating too many calories and lack of exercise, obesity is primarily driven by eating too much refined sugar, particularly fructose.
Dr. Johnson's research clearly shows that refined sugar (in particular fructose) is exceptionally effective at causing leptin resistance in animals, and it's very effective at blocking the burning of fat.
"When you give fructose to animals, they lose their ability to control their appetite, they eat more, and they exercise less. Fructose looks like it's playing a direct role in weight gain," he says.
His research also reveals that fructose has effects independent of this mechanism to induce this metabolic syndrome. Whereas fructose increases weight through the standard mechanism of stimulating more food intake and blocking the burning of fat, even when you control caloric intake, fructose can affect body composition.
This is because when you eat fructose, you actually generate more fat in your liver for the same amount of energy intake, compared to other types of sugar... For example, if you calorically restrict an animal but give it a high-fructose diet or a high-sugar diet, it will still produce fatty liver and will still become insulin resistant. According to Dr. Johnson, fructose has two effects:
- It stimulates weight gain through its effects on your appetite and by blocking the burning of fat
- It also changes your body composition to increase body fat even when you are on a caloric restriction
How Much Fructose Is Safe to Eat?
Four out of five Americans have insulin and leptin resistance. This also includes people who are overweight, diabetic, hypertensive, or taking a statin drug. If you fall into this category, it would be prudent for you to restrict your fructose consumption to about 15 to 25 grams of fructose per day from all sources.
Those who are normal weight and relatively healthy may also benefit from reducing their intake of fructose, particularly from foods containing high fructose corn syrup or sugar, as the effects of high sugar and HFCS intake may have effects that build up over time.
Fruits also have fructose but contain many beneficial nutrients and antioxidants. For someone who is obese, one has to be careful with eating fruits that have substantial fructose content. Some fruits, such as lemons and limes, have minimal fructose content and are safe. Other fruits, such as grapefruit, kiwifruit, and berries, also have relatively low fructose content and high levels of nutrients. However, fruit juices, dried fruits, and some fruits that are rich in fructose (such as pears, red apples, and plums) should be eaten relatively sparingly.
According to Dr. Johnson, if you exercise regularly, a small amount of fructose can actually be quite beneficial, because the fructose will accelerate glucose absorption in your gut and improve muscle performance. But it really depends on how your body metabolizes the fructose. Your body normally cannot absorb fructose well. But the more fructose you eat, the more the transporters that allow for fructose uptake in your gut are turned on. Hence, the more fructose your body will absorb. Lean children, for instance, tend to only absorb about half of the fructose they consume, whereas obese children who have fatty liver disease absorb close to 100 percent. This may further explain the featured finding that obesity is linked to accelerated aging in your liver.
The 19 Best Foods for Your Liver
If you're overweight or obese, in addition to losing weight you may want to focus on including more liver-protective foods in your diet. A first step would be to be sure you're drinking enough water, which will help flush toxins and waste products from your body. A general guide is to drink enough water so that your urine is pale yellow in color. As for foods, the right combination of nutrients will help keep your liver functioning optimally. Some of the best foods for your liver have been compiled by Rodale News and are listed below:5
Fermented foods: Fermented foods like cultured vegetables provide your body with beneficial bacteria that aid in digestion and provide detoxification support. The fermented food kimchi, for instance, has been found to help your body break down pesticides. Cruciferous vegetables (broccoli, cabbage, cauliflower, bok choy, and daikon): These help your liver neutralize toxins, including chemicals, pesticides, medications, and carcinogens. Dark green leafy vegetables (kale, Brussels sprouts, cabbage, and dandelion greens): These contain rich amounts of sulfur, which helps your liver with detoxification. Dandelion greens in particular are known for supporting liver detoxification and health. Sea vegetables: Various types of seaweed and brown algae also support detoxification and may also help prevent your body from absorbing heavy metals and other environmental toxins. Be sure the sea vegetables come from a non-polluted water source. Sprouts: Sprouts contain high levels of enzymes that serve as catalysts for important body functions. Recent research suggests that broccoli sprouts may help your body detox environmental pollutants such as benzene.6 From my perspective, broccoli, watercress, and sunflower sprouts are foods that virtually everyone can and would benefit from growing. Garlic, onions, shallots, and leeks: These foods are rich in sulfur, including the sulfur-based compound allicin, which is critical for liver detoxification. Organic, pastured eggs: Eggs are a high-quality source of protein that includes all eight essential amino acids. Your liver needs these to help detoxify your body. Choline, found in egg yolks, also helps protect your liver from toxins. Artichokes: These contain cynarin and silymarin, which support liver health. Mushrooms: Maitake, shiitake, and reishi mushrooms are known for their potent immunosupportive agents and also contain L-ergothioneine, a powerful antioxidant to help neutralize free radicals. Berries: Berries are rich in phytochemicals, including anthocyanin, which might inhibit the proliferation of liver cancer cells. Coconut oil: This healthy saturated fat is so easy for your body to digest that no pancreatic fat-digesting enzymes are needed. This puts less stress on your liver and helps it function optimally. Avocados: These contain healthy monounsaturated fat, oleic acid, and glutathione, which is important for liver health. Organic, unrefined, cold-pressed, extra-virgin olive oil: High-quality olive oil contains anti-inflammatory compounds that help your liver decrease oxidative stress in your body (consume this oil unheated). Flax seeds, hemp seeds, and chia seeds: These contain plant-based omega-3 fats to fight inflammation along with healthy fiber. Herbs: Many herbs support liver detoxification and function. This includes ginger, cumin, coriander, cardamom, cayenne pepper, cinnamon, fennel, and turmeric (curcumin). Organic, grass-fed meat: By avoiding meat raised on confined animal feeding operations (CAFOs) and instead choosing grass-fed meat exclusively, you'll help avoid pesticides, chemicals, hormones, and antibiotics that further tax your liver. Wild-caught sardines, anchovies, and salmon: These provide anti-inflammatory omega-3 fats. You can also find these in krill oil. Whey protein powder: Whey protein provides the amino acids necessary for glutathione production, which is essential for liver protection and function. Choose organic whey protein from grass-fed cows. Spirulina: This blue-green algae is a potent detoxifier. Animal studies suggest spirulina can also protect your liver, probably as a result of its high antioxidant properties and its ability to synthesize or release nitric oxide.
Is Coffee Beneficial for Your Liver?
Coffee has earned a negative reputation due to its caffeine content, but accumulating research suggests it may have beneficial effects, especially on your liver. One recent study revealed that people who drink three cups of coffee a day were 25 percent less likely to have abnormal liver enzyme levels than those who drank none, and this was true whether the coffee was caffeinated or not.7 Other research found that drinking two or more cups of coffee a day may reduce your risk of death from liver cirrhosis by 66 percent.8
And a Japanese study found those who drank coffee daily, or close to it, had about half the risk of hepatocellular carcinoma (HCC), a type of liver cancer, than people who never drank coffee;9 coffee is also associated with less severe liver fibrosis, lower levels of fat in your liver, and lower rates of hepatitis C disease progression.10 If you're interested in the health benefits, drink your coffee black, without sugar, non-dairy creamer or cream, or flavorings. If you really can't stand your coffee black, you could try adding non-dairy alternatives like unsweetened almond or coconut milk. Also, make sure it's organic to avoid more pesticide exposures to your liver.
Are You Struggling with Obesity?
If you're currently struggling with weight control, I urge you to read my top tips for conquering obesity now. However, a simple change for most people to make would be replacing sugary beverages with pure water and, on occasion, a healthy, anti-obesity option like hibiscus extract tea, which also offers liver-protecting potential. In addition, intermittent fasting is a powerful tool to help you resolve your insulin and leptin resistance. It's also one of the fastest ways to shed excess pounds, as it helps shift your body from burning sugar to burning fat as its primary fuel. To me, the most remarkable aspect of intermittent fasting is that once you make the transition, your hunger and cravings for sweets virtually disappears.
Granted, in order to get it right, you need to severely restrict your sugar and fructose intake. A healthy diet becomes all the more important when you start intermittently fasting. Ideally, you'll want to swap your non-vegetable carbs for healthy fats. Most benefit from anywhere from 50 to 70 percent of their daily calories in the form of healthy fat, such as avocado, olives, eggs, butter, nuts (I prefer macadamia and pecans), and coconut oil for example. This is done until the insulin resistance resolves and one has normal weight, no diabetes or hypertension, and is no longer taking statin drugs. Then one can decrease the fat and replace them with healthy carbs. For a more in-depth review, please see this previous article on how intermittent fasting can help you live longer.