Chapter 6
IN THIS CHAPTER
Consuming the right foods to help you manage your diabetes
Recognizing the importance of certain vitamins and minerals
Considering supplements for other nutrients
Some people literally go days, months, or years without exercising, but everyone has to eat on a (nearly) daily basis to stay alive and healthy, with or without diabetes. What you decide to chow down on matters to your long-term health and your blood glucose. Diabetes makes your food choices even more important.
In this chapter, I explain why your meal plan is so vital to keeping fit and how to get the most out of your body every day by making healthful choices — easily. You have a lot of tasty options that can benefit your body, both today and down the road, even if you don’t know it yet.
Have you ever chosen the salad for your main meal when you eat out only to find out that it had as many calories as that burger you would’ve preferred? Not everything you may consider healthful is, and many foods are more nutritious than you realize. Eating right in today’s world of confusing messages is tough for everyone — even those supposedly “in the know” about healthful eating.
Here’s what’s for certain: Eating foods as close to their natural state as possible is almost always best for your health. Processing foods (as when whole wheat is made into white flour, bleached or unbleached) strips numerous nutrients out of food, and only a select few are added back in. The result is that processed foods are far less nutritious than foods in a more natural state. Nutrients in foods work best the way they grew, and often the synergy of the nutrients in food is as vital as the individual nutrients themselves, so just taking supplements is seldom as effective either.
Natural fruits and vegetables are full of vitamins and minerals, and they are particularly rich in compounds called phytonutrients (or phytochemicals), which are found in plants and have disease-fighting and health-promoting powers; some examples are capsaicin, lycopene, lutein, quercetin, saponins, and terpenes. Most can’t be bought in supplement form, and you wouldn’t want to consume them without the benefits of the bioactive substances in whole foods anyway. Certain foods containing phytonutrients are considered so powerful for health that they may one day be one of the primary ways we prevent and manage diseases.
You’ve likely heard a lot already about anti-inflammatory diets. They’re supposed to be good for your health because low-level, systemic inflammation in your body can lead to plaque clogging up your arteries and insulin that doesn’t work well enough to lower your blood glucose.
An inflammatory diet is one laden with highly processed foods (many of which are “white” foods made with white flour and sugar), such as fries, pizza, and other fast foods that many Americans eat daily. This type of diet can cause your blood glucose levels to spike sky high after meals, even if you don’t have diabetes or prediabetes. Blood glucose spikes are bad for your health because they cause oxidative stress, which can lead to inflammation, insulin resistance, and so on. You get the picture.
Most of these processed foods are higher in calories and lower in nutrients like essential vitamins and minerals that make your body work well. Processing and refining foods too much takes out the good stuff (good for your body, anyway). To help keep inflammation at bay, avoid highly processed foods and sugar-rich drinks.
Because many complications from diabetes are likely related to unchecked oxidative stress in various tissues and organs, eating foods containing more antioxidant power that lower inflammation certainly can’t hurt. Focus on eating minimally processed, high-fiber, plant-based foods — that is, most fruits and vegetables, whole grains, legumes, nuts and seeds, and lean protein sources (like egg whites and whey protein). Other things have been shown to reduce inflammation, such as balsamic vinegar, fish oil, tea, cocoa, and cinnamon, but the research on those is less strong.
Particularly potent fruits to include are blueberries, strawberries, raspberries, oranges, mangoes, grapefruit (particularly pink), kiwi, avocados, concord grapes, cherries, and plums. Also eat more tomatoes, broccoli, red bell peppers, sweet potatoes, carrots, winter squash, kale, spinach, purple cabbage, and eggplant. These are the fruits and vegetables highest in vitamins A and C, folate, iron, copper, calcium, and fiber as well.
Dark chocolate and cocoa, red wine, green and black tea, and coffee also have large amounts of disease-fighting antioxidants. Don’t consume too much dark chocolate and wine, though, to avoid taking in too many calories. Also limit your coffee intake to moderate amounts because caffeine itself can decrease how well your body’s insulin works. Caffeine added to energy drinks, sports drinks, sodas, and more comes without the benefit of antioxidants found naturally in cocoa, tea, and coffee.
One thing you can almost never get too much of in your diet is fiber — and I’m not talking about the type that comes out of a drugstore container. Fiber that you find naturally in foods benefits your health in so many ways, and adding in more is easy when you know where to look for it.
Most dietary fiber is found in plants — the closer eaten to nature the better. Many manufacturers now also add fiber to products like pasta, cereals, and breads. Be cautious about taking in too much of these “fake fiber” foods (some with more than 14 grams per item) as they can cause gas, bloating, constipation, and even diarrhea. On food labels, the “total fiber” listed on the label is the sum of the natural dietary fiber in foods plus any added fiber put into products during manufacturing.
Most people don’t eat enough fiber for optimal health. At a minimum, you need at least 14 grams of fiber for every 1,000 calories you eat. Adult women need less than men because they eat fewer calories. After you reach age 50, recommended minimum fiber intake drops again for both men and women because you need fewer calories as you get older. Eating as much natural fiber as possible (even more than the minimum) should be your daily goal, no matter how young or old you are. Table 6-1 shows USDA’s minimum recommendations for fiber intake.
TABLE 6-1 Recommended Minimum Daily Dietary Fiber Intake
Age |
Men |
Women |
19 to 50 years |
38 grams |
25 grams |
Over 50 years |
30 grams |
21 grams |
Having a healthful diet while eating carbohydrates is entirely possible if you keep a few concepts in mind. A balanced meal plan for the average person, according to the latest dietary recommendations from the Institute of Medicine of The National Academies, contains 45 to 65 percent of calories from carbohydrate, 20 to 35 percent of calories from fat, and 10 to 35 percent from protein. The American Diabetes Association does not recommend any particular intake of calories from each of these categories, and people with diabetes follow a variety of individualized meal plans.
A lower-carbohydrate intake, in addition to potentially lowering your blood lipids and your blood glucose, does help some people lose weight faster (at least initially) and keep it off, although how well this works varies by the person. Part of the confusion about how many carbohydrates you should eat when you have diabetes comes from the research itself. Many “low carbohydrate” meal plans studied are only as low as 40 percent of calories from carbohydrates, although some people follow extremely low-carbohydrate eating (less than 10 percent of calories). If you take insulin to manage diabetes, balancing calorie intake from all sources is likely as important or more important than just focusing on carbohydrate intake alone.
Losing body fat is generally harder when your insulin levels are high, which they’ll be after you release, inject, or pump enough insulin to cover your higher intake of carbohydrates, especially those that cause your blood glucose to rise rapidly. Because fat cells remain responsive to insulin, even when your blood glucose runs high, you’ll gain fat weight when your liver converts some of that glucose into fat and stores it.
How rapidly a carbohydrate is digested, or its glycemic index (GI), affects your body’s insulin responses and ability to manage your blood glucose. The more rapidly the body breaks down a food, the faster the carbohydrate is turned into glucose in your bloodstream. To manage the influx of glucose coming from carbohydrates, your body needs insulin. If you have diabetes or prediabetes, you may not be able to cover these glucose spikes with enough insulin.
GI values are usually scaled from 0 to 100, with glucose (the simple sugar, but also the same as what’s in your bloodstream) having a GI of 100. The GI of a specific food can differ by person; other factors that can affect it include the following:
For example, thick linguine has a lower GI value than thin spaghetti. Overcooking in general raises the GI value of foods, so al dente pasta is always better. Highly acidic foods like vinegar can lower the GI value of another food when eaten in combination. Cold storage increases the resistant starch content (carbohydrates that are hard to digest) by more than a third, and the acid in lemon juice, lime juice, or vinegar will slow stomach emptying.
An excessive intake of high-GI carbohydrate foods can increase insulin resistance even in people without diabetes. The GI values of foods have mainly been determined in nondiabetic individuals, so a given food’s effect may be exaggerated if your body releases less insulin or your insulin action is impaired. If anything, GI values may underestimate rather than overestimate the glycemic spikes caused by most carbohydrate-rich foods if you have diabetes.
In a study done in overweight adults, insulin resistance decreases when they eat a low-GI, whole-grain diet compared to a refined, “white” diet. In some studies, people with type 2 diabetes who follow a diet with a GI of less than 40 tend to improve their overall blood glucose, enhance insulin action, lower bad blood fats, and lose weight. Such positive results support the GI as an appropriate guide to eating, whether you have diabetes, prediabetes, or insulin resistance, or if you just want to stay healthy.
For carbohydrates, portion size does matter. Glycemic load (GL) is a measure of both GI value and total carbohydrate intake in a typical serving. Paying attention to your GL is even more important with diabetes. A high-GI/GL diet will most likely worsen insulin resistance and overtax your body’s ability to supply insulin, so limit your intake of foods with both a medium or high GI value and a high GL.
A GL of 20 or more is high, 11 to 19 is medium, and 10 or less is low. For a single serving of a food, having a GL over 20 means it is carbohydrate dense, even if the spike in your blood glucose may be slower or smaller (like when you eat most pasta). Though GI is defined for each type of food, GL can also be calculated for any size serving of a food, an entire meal, or an entire day's meals if you want to get a feel for how many carbs you’re taking in.
Any carbohydrate-heavy meal with a high GL requires more insulin, but if the GI value isn’t also high — as is generally the case with high-fiber foods — your blood glucose will stay lower. Legumes, which are rich in protein and fiber, contain carbohydrates with a lower GI.
A low-GL, high-fiber diet also raises circulating levels of adiponectin, an anti-inflammatory hormone released by fat cells that can increase your insulin action and improve your blood glucose. A low-GI/GL diet plan results in weight loss as well.
Foods that are higher in fiber are usually lower in added sugars, along with having less fat and fewer calories. White (table) sugar boosts your blood glucose less quickly than white potatoes do, but the negative effects of eating a lot of sugar and other refined carbohydrates can be significant, particularly given their lack of essential nutrients (besides calories). What’s more, there is nothing inherently evil about fructose (fruit sugar), despite research suggesting that high-fructose corn syrup in beverages leads to a fatty liver. Taking in excess calories more likely leads to such health issues, not fructose by itself. That said, sugars (and carbohydrates) may be somewhat addictive as they cause the release of brain hormones like dopamine (in the pleasure center) in response to their intake.
The latest nutritional fad is the high-protein diet, including protein shakes, supplements, and more. This approach isn’t necessarily a bad thing. The major building blocks of protein are amino acids. About half of these 20 amino acids are essential, meaning you must eat those, but your body can form the rest. Protein doesn’t cause rapid spikes in blood glucose levels. Eating protein also makes you feel full longer, whereas low-protein diets are associated with increased hunger. Consuming more lean protein together with more healthful fats may reduce your appetite and help you eat fewer calories and even lose weight if that is your goal. (The following section covers healthy fats.)
Your body metabolizes foods with lots of protein more slowly than it does carbohydrates, usually within three to four hours. Eating as much as 30 to 40 percent of your daily calories as protein, with a lower intake of carbohydrates and fats, may help with managing your blood glucose, losing weight, and keeping the weight off.
Some studies have shown that a diet rich in soy protein may be beneficial for people with type 2 diabetes. Soy protein consumption has a significant positive impact on heart disease risk and kidney problems in adults with type 2 diabetes with existing kidney disease. Eating soy protein lowered levels of blood glucose, blood fats, and C-reactive protein (an indicator of inflammation) and markers of kidney disease. Too much of anything — including soy — is not recommended, though.
Having diabetes — particularly when your blood glucose isn’t well managed — can contribute to unhealthy changes in your blood fats. High triglycerides (mainly from dietary fat, but also formed in your body when you eat highly refined carbohydrates) and bad types of cholesterol play a major role in stimulating inflammation that can cause plaque to form in your arteries (a common occurrence in people with diabetes).
Not every type of fat is bad for you — although the nutrition world is still hotly debating the healthfulness of various fats — but a high intake of certain types of fat definitely can contribute to the development of insulin resistance and bad changes in blood fats as much as an excess intake of refined carbohydrates can.
Two dietary polyunsaturated fats are essential: omega-3 and omega-6 fatty acids. Both are important to include in a healthy diet, particularly when you have diabetes and your nutrition is even more important in preserving your long-term health.
Omega-3 fats are abundant in dark green, leafy vegetables (for example, dark-colored lettuce, spinach, kale, turnip greens, and so on), canola oil, flaxseed oil, soy, some nuts (such as walnuts), fish, and fish oils. Only fish and fish oils contain larger amounts of two omega-3 fats called DHA (docosahexaenoic acid) and EPA (ecosapentanoic acid), which are critical for brain and nerve function, cardiovascular health, and more. Plant foods like walnuts contain mainly a third essential omega-3 fat called ALA (alpha-linolenic acid), which your body can convert into the other two if your intake of them is low. Omega-6 fats are abundant in the corn, sunflower, peanut, and soy oils that are used in making margarine, salad dressing, and cooking oils, and these oils may help lower inflammation. Because some studies have suggested that taking in too many omega-6 fats can lead to inflammation, just try to balance out your intake of the two types to optimize your health.
Diets high in certain types of fats — like the plant-based ones found naturally in avocados — may improve your body’s insulin action. Even tropical oils like coconut that are minimally processed are now considered healthier options even though most of their fats are saturated.
It also now appears that unhealthful carbohydrates may impact your blood cholesterol and fats more than the fat that you eat. If you choose to eat a diet that falls within the general guidelines for all adults (20 to 35 percent of your total daily calories) and avoid lower-fat versions of snack foods that have added sugar and more refined carbohydrates in them, your blood cholesterol levels are more likely to go down.
Trans fats are mostly created by manufacturers when they hydrogenate or partially hydrogenate liquid oils to alter their texture. Consuming trans fats found in hydrogenated oils contributes to insulin resistance and makes keeping blood glucose and cholesterol levels under control more difficult. Their inclusion on food labels has led to fewer of them being added to foods by manufacturers, thankfully.
Found most abundantly in processed foods such as crackers, cookies, baked goods, and more, trans fats may be disguised as mono- and diglycerides, stearate, palmitate, lard, vegetable shortening, and hydrogenated or partially hydrogenated oils. Trans fats from natural sources, however, aren’t unhealthy like the manufactured ones (you’ll find a small amount in dairy products that is natural), and most foods contain very little of these anyway.
Eating even one meal high in manufactured trans or some saturated fats can interrupt the normal flow of blood through your arteries and veins for hours afterward and make your body’s response to insulin sluggish as well. On the other hand, when you eat a high-fat breakfast that contains mostly a good fat like olive oil (rather than, say, sausage), your blood glucose and insulin levels stay lower. Your blood cholesterol should decrease as you reduce trans, saturated, and highly processed fats in your diet.
Although current research is unclear as to whether unprocessed red meats directly cause heart disease, more healthful choices are available, including fish, nuts and seeds, legumes, fruits, and vegetables. If you consume cheese and milk, pick lower-fat varieties — not because dairy fat is bad for your health but rather to take in fewer calories.
Also, diets rich in the monounsaturated fats in nuts and seeds (as well as olive and canola oil) are heart-healthy and don’t necessarily promote weight gain if eaten in moderation. Just don’t eat the whole jar in one sitting!
Here are some easy tips for preparing and choosing more healthful meals:
Obtaining nutrients naturally through your foods if you can is always best because they contain many important phytonutrients (such as flavonols, polyphenols, catechins, and lycopenes) that aren’t available in an optimal form through dietary supplements. Taking large supplemental doses of any vitamins, minerals, or other nutrients can be counterproductive, though. For example, almost all antioxidant vitamins and minerals can actually cause damage when you take too much. Head to the later section “Antioxidants” for more on supplementing with these substances.
You can’t overdose on antioxidants if you obtain them naturally through food, though, so get them that way whenever possible. The following sections discuss some of the most important vitamins and minerals for people with diabetes.
The vitamins in the B family include thiamin (B1), riboflavin (B2), B6, niacin, B12, folate, biotin, and pantothenic acid. These vitamins are involved in the digestion and metabolism of food, so it’s not surprising that a deficiency in any of them can adversely affect your body’s handling of carbohydrate, protein, fat, and more.
People with diabetes are more likely to be deficient in thiamin, and supplementing with this vitamin has been shown to prevent some diabetic complications and improve insulin action in adults with type 2 diabetes. Vitamin B6 and others in the B family may be effective in preventing the formation of harmful substances in blood (advanced glycation end products) associated with diabetes complications. Vitamin B12 deficiency is also quite common in people with type 2 diabetes or prediabetes, particularly if they take metformin, which can cause depletion of this vitamin over time (as well as symptoms of nerve damage). Low blood levels of vitamin B12 are associated with neuropathy-like symptoms that may be reversible with supplements.
Make sure that your daily diet contains at least 100 percent of all the B vitamins (their content should be listed on the label), and consider taking at least a general B vitamin supplement of 100 percent of the RDA if you have any deficiencies that can’t be corrected naturally through your diet. Supplemental doses of B vitamins are generally harmless because you lose any excess through your urine, but taking megadoses of these vitamins isn’t necessary or advisable. For example, taking large doses of supplemental folate can mask a deficiency of vitamin B12 and cause other symptoms like nausea, and too much B6 can cause permanent nerve damage.
If you have diabetes, you may want to talk to your doctor about supplementing with thiamin or benfotiamine, a derivative of vitamin B1 (thiamin) with additional antioxidant properties, because both have been used to treat neuropathic pain. They may also prevent other complications, improve insulin action, and lower your blood cholesterol levels.
Vitamin D is unique in that it functions as a hormone. All the cells in your body have a receptor for it. Long associated with bone health, its effects are far-reaching: It can lower the risk of developing some autoimmune diseases, certain types of cancer, diabetes, infectious diseases, heart disease, asthma, and neuropathy. Having enough vitamin D in your body also lowers your risk of dying from any cause.
The body derives most active vitamin D (about 90 percent) from limited exposure to sunlight, which is why this vitamin is often called the “sunshine vitamin.” Apparently, you need to get sunshine on your face and hands for a only few minutes a couple of times a week to create what you need in your body (depending on the time of year, of course, and where you live).
Still, many people with diabetes have low blood levels of this vitamin. Older adults also don’t create as much vitamin D in their skin with sunlight exposure, and taking in enough through your diet alone is hard.
Magnesium, an abundant mineral in the body, is involved in over 300 of the body’s metabolic reactions. It improves your insulin action, so not having enough magnesium isn’t good for your diabetes management. A magnesium deficiency can contribute to insulin resistance and raises your risk for developing type 2 diabetes (if you don’t have it already). Low magnesium levels in adults with diabetes are also associated with eye disease, nerve damage, and depression. If you’re getting muscle cramps frequently, you may be deficient in magnesium.
This mineral is widely distributed in foods like unprocessed (whole) grains, nuts, legumes, and even dark chocolate (thank goodness for that!). You can lose some magnesium through urinating more when hyperglycemic or sweating excessively (such as during exercise).
Particularly if your blood glucose management could be better, you may want to consider taking a daily magnesium supplement, along with eating a more healthful diet. Taking too much magnesium can cause temporary diarrhea, but it’s otherwise safe. But don’t take more than 350 milligrams daily.
Although diabetes can create a special metabolic situation that depletes certain vitamins and minerals from your body, you may be able to compensate with more healthful food choices, certain nutritional supplements, and improved blood glucose management. If you’re getting the recommended daily amounts of vitamins and minerals in your diet, then you may not need any supplements — which are only beneficial if you’re truly deficient. Insulin resistance and hyperglycemia can potentially cause certain deficiencies, but if you manage these conditions effectively, supplements are not universally recommended and could potentially be harmful.
If you decide to use home remedies or supplements, keep in mind that the term herbal or natural on a label doesn’t mean that a product is harmless. In fact, many common poisons found in plants like hemlock and deadly nightshade are “natural.” Some dietary supplements may have undesirable side effects; for example, certain forms of ginseng can raise blood pressure, and mugwort can cause dermatitis (skin inflammation).
Other “natural” supplements can interact with your prescribed medications to produce side effects or possibly negate the usual effects of the medication. For instance, people have been poisoned, in some cases fatally, by taking herbal preparations containing heliotropium while also taking a prescribed barbiturate. Also, there is no evidence showing how those supplements or herbs can interact with your current diabetes medications, so be extra careful with taking them.
What’s more, the supplements you buy may vary widely in their actual content. Some studies have shown no ginseng in products that are sold as ginseng supplements, and the packaging for many herbal preparations doesn’t list the ingredients. Even when products do disclose the ingredients, the lists may not be accurate or complete. Up to 26 percent of all dietary supplements tested in one study contained contaminants sufficient to elicit a positive drug test in competitive athletes. Others may contain harmful and even potentially fatal contaminants.
Creatine is a natural compound, normally found in muscle, that is involved in short-term energy production. It’s well established as an effective supplement in weight lifters and other power athletes who are gaining muscle mass, but only when they’re training. Taking creatine supplements in combination with doing resistance training may increase your strength gains from training and lower your insulin resistance, but doing so certainly isn’t a requirement if you want to get stronger by doing such training. Talk to your doctor first about whether you should use creatine if you have any issues with the health of your kidneys.
Leucine, an essential amino acid found mainly in whey protein derived from cow’s milk, is an important building block for muscles, and consuming adequate amounts of it is essential. Eating quality protein and getting enough calories are the preferred (and less expensive) method, but you can also find L-leucine (as well as creatine, which I discuss in the preceding section) as a dietary supplement in stores. You also get it as part of whey protein supplements or blends.
Many people with diabetes or undergoing renal dialysis are deficient in carnitine, which your body produces from amino acids. If your body makes enough, you don’t need to supplement or to worry about consuming any carnitine in food. Having enough is important, though, because carnitine increases your insulin action and is essential for metabolizing fats and carbohydrates.
If you’re deficient in carnitine, you can obtain it by eating meat, fish, poultry, and milk. It’s most concentrated in whey protein (dairy products), but it’s also safe to take as a supplement of L-carnitine or acetyl-L-carnitine, usually in 500- or 1,000-milligram doses.
Carnitine supplementation can improve insulin sensitivity by decreasing fat levels and glucose in blood. It may also help lessen some diabetes complications. In a study of 1,200 diabetic patients, researchers found that treatment of type 1 or type 2 diabetes with acetyl-L-carnitine (500-milligram or 1,000-milligram doses daily) for a year relieved diabetes-related nerve pain in feet and improved sensation of vibration. Thus, it may help delay progression of neuropathic pain or reduce its severity.
One of the latest crazes is everyone taking antioxidants to stay young. Supplements containing antioxidants are supposed to be able to slow aging by preventing cumulative oxidative damage in the body. However, consistent research is lacking. Elevated blood glucose is one of the conditions that can trigger such damage caused by excess free radicals (compounds that cause oxidative damage and inflammation).
Normally, your body has enough antioxidant enzymes naturally to fight most or all the free radicals that are created. These radical compounds, if left unchecked, promote further insulin resistance and lower insulin secretion. Diabetes not only increases free radical generation when your blood glucose is elevated but can also depress your body’s natural antioxidant defenses. (Exercise stimulates the production of these radicals, but it also enhances your body’s natural antioxidant enzymes systems that get rid of them.) If your blood glucose levels aren’t well managed, you’re more likely to benefit from supplemental antioxidant therapies.
The antioxidants with the most potential benefit for anyone with diabetes are glutathione, alpha-lipoic acid, vitamin C, vitamin E, beta-carotene, selenium, copper, and zinc.
Glutathione is the main antioxidant enzyme found in all your cells, and, along with alpha-lipoic acid, is the most important antioxidant in your body. It protects the DNA in your cell nuclei from being oxidized. Having diabetes likely increases your need for glutathione and alpha-lipoic acid by depleting glutathione levels when your blood glucose is elevated, potentially leading to diabetes-related cataracts and other complications. Although your body can synthesize both from amino acids found abundantly in foods like asparagus, avocados, spinach, strawberries, peaches, melons, and citrus fruits, it may not always make enough to meet your body’s needs.
Alpha-lipoic acid increases glutathione levels by helping cells absorb a critical amino acid needed for its synthesis, and it works to prevent stroke, heart attacks, peripheral nerve damage, and cataracts, as well as memory loss, cancer, and aging effects. Spinach (raw or cooked) is the best source of this nutrient, also found naturally in small amounts in broccoli, tomatoes, potatoes, peas, and Brussels sprouts. Spinach is especially touted for its ability to fight diabetic cataracts and macular degeneration (the leading cause of blindness in adults).
Alpha-lipoic acid supplements may normalize diabetes-induced kidney dysfunction and damage to nerve cells, where they additionally promote nerve fiber regeneration and stimulate a substance known as nerve growth factor. In Germany, alpha-lipoic acid has been used for years to treat painful diabetic neuropathy in the feet and hands, and it can also improve autonomic (central nervous system) neuropathy. Most people can safely take 600 milligrams once or twice daily for relief of symptoms.
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