We Are What We Eat
Sugar Is the New Tobacco, so Let’s Treat It That Way
headline in Medscape Psychiatry, October 31, 2016
Who doesn’t like a sweet treat—some candy, cake, ice cream, or pie? Many of today’s seniors remember Shirley Temple singing, “The Good Ship Lollipop,” “a sweet trip to the candy shop”; crackerjacks, peppermint, tootsie rolls, devil’s food cake, and if you eat too much “you’ll awake with a tummy ache.”
But the sad truth is that sugar has done far more harm than giving a tummy ache. Sugar consumption has been associated with negative changes in cholesterol,1 heart disease,2 impaired learning and memory,3 and accelerated aging. Sugar consumption in America (and the Western world) has dramatically increased over the last two hundred years. According to Forbes Magazine sugar consumption in the United States increased from fewer than 10 pounds per person per year in 1820 to over 130 pounds per person per year in 2012.4
How does sugar consumption accelerate aging? There appear to be several potential pathways. At the end of chapter 4 we discussed telomeres and cellular replication. As telomeres shorten, cells lose the ability to replicate—the shorter the telomeres, the shorter the remaining lifespan. A study published in 2014 documented that individuals with high sugar consumption had shorter telomeres in their white blood cells when compared to individuals with lower sugar consumption.5 These differences remained after controlling for sociodemographic and health-related differences. So one factor in how high sugar intake may accelerate aging is by shortening telomeres.
Another factor is that diets high in sugar typically are composed of more refined, highly processed foods. Such diets are generally lower in micronutrients, vitamins, minerals, and healthy molecules such as fiber and flavonoids. Without an ongoing supply of the building-block molecules the body needs to produce its varied different tissues, the cells fatigue, wear out, and die easier. So a second factor in how a high-sugar diet accelerates aging is by decreasing the intake of vital nutrients necessary to keep the body operating at peak efficiency.
It is well documented that long-term patterns of living (lifestyle choices) that increase inflammation will accelerate aging, reduce brain volume, and increase dementia risk. This is because chronic inflammation damages the body’s tissues, including the brain, leading to the changes associated with Alzheimer’s disease. We will describe the inflammatory cascade contributing to Alzheimer’s disease in detail in chapter 14. And in the next section we examine one pathway in which chronic high sugar increases inflammation and accelerates aging and dementia risk. But what is less commonly known is that brief exposure to high-sugar intake also impairs memory and learning. A recent animal study found that one week of consuming a diet high in sugar impaired memory. The researchers documented that the high-sugar intake increased inflammation in the brain cells (hippocampus) where new memories are formed, thus impairing their function and causing memory deficits.6 Therefore, reducing the consumption of sugar in the diet will both provide immediate benefit and reduce your risk of dementia in the long term.
Glycation
Another factor in how sugar accelerates aging, which has significant scientific validation, is that increased sugar in the diet results in increased oxidation via a mechanism called glycation. Glycation is the process of a glucose (sugar) molecule binding to other molecules such as proteins and DNA where it does not normally belong. When the sugar molecule binds inappropriately to a protein it forms a new compound, advanced glycation end-product, or AGE. AGEs react with body tissues to produce free radicals and reactive oxygen species (ROS). Both AGEs and high-sugar (sucrose) intake trigger the immune system to increase chemokines, cytokines, and other inflammatory factors (as described in chap. 5), all of which increase oxidative stress on the body. Remember, oxidation is the process of oxygen atoms binding with other molecules and damaging them. Therefore, these unnatural oxidizing molecules are damaging to our bodies, including skin, blood vessels, nerve cells, and other organs, and just as the acronym AGE suggests, they ultimately accelerate the aging process.
Here’s an example. Hemoglobin is the molecule in our red blood cells that carries oxygen. But when glucose binds to hemoglobin in this unnatural way a new compound is formed called hemoglobin-A1C (HGB-A1C). This new aberrant molecule is highly damaging, causing injury to cells throughout the body. The higher the blood sugar levels, the higher the abnormal AGEs. Diabetics, with higher than normal glucose levels, have elevated levels of HGB-A1C with increased oxidative damage that causes many of the problems common to diabetics—neuropathy (damage to the nerves in the body that causes burning or numbness), retinal damage (causing vision problems), kidney damage, and dementia.
These inflammatory molecules also damage collagen (the protein in the body that provides elasticity, pliability, and strength). When AGEs bind to collagen in the skin they cause the skin to thin, wrinkle, and lose elasticity—accelerating aging!7
AGEs bind with LDL (low-density lipoprotein) cholesterol, forming plaques in the walls of blood vessels, and the AGEs impair the body’s ability for our good cholesterol, HDL (high-density lipoprotein), to remove the plaques. AGEs alter vascular permeability and blood flow, contributing to vascular disease and the subsequent health problems associated with vascular compromise such as heart attacks and strokes, and thereby accelerate aging.8
Obviously, anything that impairs blood flow to the brain would have both short- and long-term negative consequences. The blood brings oxygen, nutrients, and energy molecules to the brain and also removes waste products. A compromised circulation would undermine normal metabolism and brain function. But most significantly, impaired blood flow can result in strokes—the death of brain cells due to loss of blood to that brain region. When the blocked blood vessel is large it results in a large stroke, and most of us have seen the sad results of these—paralysis of one side of the body and often the loss of normal speech. What many people don’t realize is that chronic inflammation, with subsequent plugging up of the arteries with plaques, increases the risk of not only large artery strokes but also small vessel strokes. The small vessel strokes do not cause the paralysis or sudden loss of speech but instead cause the loss of a few neurons or neuron-to-neuron connections. Over the course of years these small losses add up to big losses and cause vascular dementia—dementia due to the blood vessel disease that obstructed blood flow causing the death of neurons.
Clearly, elevated levels of advanced glycated end-products are damaging to our bodies and contribute to accelerated aging as well as the risk of dementia. So what are the sources of these AGEs and how can we reduce them?
The two primary sources of glycation are the body’s own metabolism and the foods we eat. The greater our consumption of sugary foods, the greater concentration of sugar molecules in the body, which results in increased production of AGEs. Anything that increases the blood sugar levels will increase the body’s production of advanced glycation end-products. Sugar-filled snacks, foods with high glycemic index, and foods containing high fructose corn syrup all increase the production of these damaging molecules.
Certain forms of cooking and food preparation will form AGEs before we even eat the food, and then our bodies will absorb about 30 percent of the AGEs that we ingest. Foods high in these damaging molecules are fried foods, charred foods, and grilled foods. Examples of such foods are fried chicken, grilled burgers, seared steaks, French fries, and caramelized onions. Eating such foods increases inflammation and thereby accelerates aging.
A simple way to reduce AGEs in your body is to reduce the consumption of sugar, high fructose corn syrup, fried foods, and charred and grilled foods. Slow cooking such as using a Crock-Pot, cooking with water, and boiling foods avoids the formation of glycated proteins from cooking. Additionally, eating complex carbohydrates and foods high in fiber reduces the production of these toxic molecules in the body.
Dietary scavengers that help clear your body of these glycated proteins include apples, broccoli, spinach, kale, collard greens, peaches, cabbage, cauliflower, tomatoes, carrots, citrus fruits, most berries, omega-3 fatty acids, rhodiola rosea, green tea, grape seed extract, carnosine, and vitamin B6.
Many people know that sugary diets are unhealthy yet have struggled to move to a healthier, less-sugar-rich diet. This may be due to the ability of high-sugar diets to change the brain’s reward circuitry such that healthy foods are not as enjoyable or pleasurable as they would have otherwise been.9
Imagine working in your yard one afternoon and after several hours you find yourself ravenously hungry. You are pleasantly surprised when your spouse brings you a snack of perfectly ripe fresh strawberries. Can you imagine how sweet and refreshing one would taste? But now consider if you had just finished swallowing your last bite of a candy bar and your spouse offers you the same strawberries—how would one taste now? What is the difference? Has the sweetness of the strawberries changed? No, your ability to experience the sweetness of the strawberries has been changed. By eating a candy bar, or any other food with unnatural sweetness (artificially concentrated levels of sugar), we overstimulate the brain’s reward circuits so that foods with natural sweetness are no longer as enjoyable, pleasurable, or desirable as they would otherwise be. If we do this on a rare occasion the taste receptors reset quickly, and in a few hours we can enjoy the strawberries. But if we do this chronically we actually lose “taste” for healthy foods and develop cravings or tastes for highly toxic and overly sugary-sweet foods. Thus our diets will gravitate toward patterns of eating that will accelerate aging. If we choose to change our diets and consistently eat healthier foods we retrain our brains, and the foods we initially found distasteful will become enjoyable. This usually takes about three months.
Perhaps you know people who were diagnosed with high blood pressure and instructed to eat a low-salt diet. Initially, they may have complained that the food tasted bland, but if they stuck with the new diet, after several months of low salt not only did food taste good again but also food with the previous levels of salt typically tasted too salty. Research documents that this change in taste preference takes about three months.10
Another example can be found in people who switched from sugary sodas to diet sodas. Initially most find the diet sodas less enjoyable, but if they continue to drink the diet sodas over months they come to prefer them to the sugary sodas. Why? Because our taste receptors and reward pathways change based on our experience. Unfortunately, diet sodas are no healthier and, in fact, may contribute to a greater risk of dementia than the sugary ones. One large study of more than five hundred thousand people ages fifty to seventy-one followed for ten years found drinks with artificial sweeteners increased rates of depression, whereas drinks with sugar or honey did not.11 Recent research on depression has documented that one of the underlying pathways that causes depression is increased inflammation. Thus, anything that increases inflammation will increase depression risk as well as dementia risk. This is likely the reason that having a history of depression increases the risk of dementia—both problems are being caused by chronic inflammatory cascades damaging brain tissue and interfering with normal brain function.
Soft drinks have other age-accelerating effects besides the sugar they contain. Several studies have linked soft drink consumption with accelerated bone loss, which may contribute to osteopenia and osteoporosis as we age.12 Colas were found to be more likely to contribute to such bone loss.13 Not surprisingly, studies have linked increasing intake of sugary soft drinks with increased obesity and type 2 diabetes—both of which accelerate aging.14 And interestingly, even when individuals drank diet soft drinks that used artificial sweeteners rather than sugar, obesity rates still increased.15 Why might this be? No firm conclusion exists at this point, but one possibility is that these substances also artificially stimulate the brain’s taste receptors and reward circuitry and may result in natural, healthy foods being less enjoyable, thus leading to dietary choices that overall are unhealthier.
Junk foods and fast foods such as pizzas, hot dogs, doughnuts, cookies, cakes, and so on increase inflammation, promote insulin resistance, and increase the risk of diabetes and obesity. All these factors accelerate aging and increase the risk of dementia later in life. But decades before dementia occurs, these unhealthy lifestyle choices cause other problems undermining well-being. Studies show that individuals who eat junk food regularly have a 40 percent higher rate of depression than those who do not eat such foods. And the impact was dose dependent, meaning the more junk food consumed, the greater the likelihood of depression.16 This is most likely due to the elevation in inflammation triggered by such food choices.
Diets high in sugar and trans fats (trans fats are produced industrially when hydrogen is added to vegetable oils to turn liquid oils into solid fats; they appear as “partially hydrogenated oils” on food labels) accelerate aging through multiple mechanisms: (1) glycation increasing oxidative damage to body and brain, (2) increased obesity, which further increases oxidative damage, (3) diets lower in essential nutrients, and (4) altered taste reception driving toward a more sugary diet.
What lifestyle changes can we make—besides simply reducing sugar intake and eating more whole foods—that will slow the aging process, including aging of the brain?
Fasting
Have you ever fasted? I have always wondered why they call it fasting when the time goes by so slowly! Regardless of how slow it seems to pass, research has documented that caloric restriction or intermittent fasting slows aging, improves brain health, and prolongs life.17 The mechanism for this appears to be via a reduction in oxidation and inflammation.18
Historically, the reason our morning meal is called breakfast, which literally meant to “break the fast,” is because there was a fast between dinner and breakfast. The easiest way to implement fasting into your life is to implement a daily twelve-hour fast between dinner and breakfast. Not only does such a regular fast appear to slow aging, but one small study also showed that a daily twelve-hour fast, in conjunction with other lifestyle changes, improved memory and cognition in individuals who had already lost abilities. In this study of ten individuals who had either mild cognitive impairment or early Alzheimer’s dementia, nine out of the ten persons showed measurable improvements within three to six months of entering the lifestyle program.19
In addition to fasting twelve hours each night, this lifestyle program included the following:
Diet and the Brain
Recent brain science examined blood markers of diet and identified three distinct dietary patterns detectible in the blood of those studied. Two patterns were associated with greater brain volume and improved cognitive performance, while one dietary pattern was associated with brain-volume loss and worsening cognitive performance. The dietary patterns associated with improved brain function and volume were either the vegan diet high in B vitamins and vitamins C, D, and E (fruits, nuts, grains, veggies) or the Mediterranean diet high in omega-3 fatty acids (fish oils). The dietary pattern associated with poor brain function and volume was the typical American diet of high sugar, fast foods, and trans fats (junk food).20
Diets high in or supplemented with long-chain omega-3 fatty acids found primarily in oily fish (EPA/DHA) appear to protect the brain and slow loss of gray matter. After the age of seventy the human brain generally shrinks by 0.5 percent per year. A study published in 2014 in Neurology that followed more than eleven hundred women for eight years found that women with the highest levels of EPA and DHA in their blood at the beginning of the study had brains that were about two cubic centimeters larger overall than women with the lowest amounts of these fatty acids. Further, the hippocampi, which is where new memories are formed, were 2.7 percent larger in women whose EPA/DHA levels were twice as high as the average. This study adjusted for other factors that could influence the participant’s brain size such as education, age, other health conditions, smoking, and exercise.21
There are multiple potential reasons that a diet high in omega-3 fatty acids (EPA/DHA) yields better brain volume, cognition, and memory. DHA in the brain concentrates in the lipid membrane and improves neuronal fluidity, signaling, synaptic plasticity (ability to make new neuron-to-neuron connections), and neurogenesis (production of new neurons) and has a significant anti-inflammatory role.22 Additionally, recent research published in the Journal of the Federation of American Societies for Experimental Biology suggests that omega-3-fatty acids from fish oil improve the function of the brain’s glymphatic system, which is the system the brain uses to remove waste products, including amyloid protein—a protein that has been associated with Alzheimer’s disease.23
EPA/DHA forms of omega-3-fatty acids are primarily found in oily fish, wild salmon, mackerel, and sardines. Omega-3s from plant sources such as flax seed are the shorter-chain form ALA, which the brain cannot use. Studies demonstrate that ALA is poorly converted in the body to the longer-chain forms: 8 percent to EPA and less than 1 percent to DHA.24 Therefore, a healthy brain requires a diet high in the vital fatty acids, which means either a diet high in oily fish or taking daily omega-3 fatty acid (EPA/DHA) supplements.
LEARNING POINTS