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If black beans, cashews and Swiss chard aren't part of your regular diet, it's time to rethink your menu. Eating plenty of these and other magnesium-packed foods is tied to powerful protection from diabetes.

According to a new study published this month in Diabetes Care, adults with the highest – versus lowest – intake of magnesium were half as likely to develop Type 2 diabetes. Magnesium-rich diets were also linked with a 37-per-cent reduced risk of developing prediabetes.

It's estimated only half of North Americans achieve daily targets for magnesium: 310-320 milligrams for women and 400-420 mg for men. (In the current study, a daily magnesium intake of less than 260 mg was defined as low; participants with a high intake consumed 400 mg, on average, per day.)

More than nine million Canadians have diabetes or prediabetes, a number that's expected to rise. It's also a number that's largely preventable by managing weight, exercising more and eating a healthy diet that minimizes refined carbohydrates.

Type 2 diabetes occurs when the pancreas doesn't produce enough insulin, the hormone that removes glucose (sugar) from the bloodstream, or when the body doesn't properly use the insulin it makes. A fasting blood glucose of 7 mmol/L or higher indicates Type 2 diabetes. (Normal fasting glucose is considered 4 to 6 mmol/L.)

Prediabetes, also called impaired fasting glucose, occurs when blood sugar is higher than normal (6.1-6.9 mmol/L), but not high enough to be considered diabetes. Some of the long-term complications of diabetes, such as heart disease and nerve damage, begin during prediabetes.

The study, which followed 2,582 adults (average age 54) for seven years, also determined that a high magnesium intake cut the risk of prediabetes progressing to Type 2 diabetes by one-third. Magnesium is needed for the proper action of insulin; too little can cause insulin resistance, a precursor for Type 2 diabetes. Excellent sources of the mineral include legumes, nuts, leafy greens, halibut, yogurt and wheat germ.

The following foods can give you an edge against prediabetes and Type 2 diabetes.

Black beans

When it comes to legumes, black beans are a top source of magnesium (second to soybeans): a 3/4 cup serving delivers 100 mg of the glucose-regulating mineral. For convenience, buy canned black beans; drain and rinse them before using. Add black beans to chilis, soups, salads and tacos.

Also eat: chickpeas, lentils, kidney beans, soybeans, tofu, edamame.


Among people with prediabetes, eating an almond-rich diet has been shown to improve insulin sensitivity and lower LDL (bad) cholesterol. Among individuals with normal blood sugar, regular nut consumption is linked with a lower risk of Type 2 diabetes and heart disease.

Nuts are a good source of cardio-protective nutrients including unsaturated fat, fibre, folate, vitamin E and potassium. They're also high in magnesium, with almonds, cashews and peanuts leading the pack.

Add nuts to breakfast cereal, yogurt, stir-frys and whole-grain pilafs. Eat a small handful of nuts for a midday snack. (One serving = 24 almonds, 18 cashews, 28 peanuts or 20 pecan halves.)

Also eat: Brazil nuts, cashews, hazelnuts, peanuts, peanut butter, pecans, pistachios, almond butter.


Eating more leafy green vegetables – 1.3 servings daily versus only one per week – is associated with a lower risk of diabetes (1 serving = 1/2 cup cooked or 1 cup raw). Antioxidants and magnesium in leafy greens are thought to be responsible for their protective effects.

Add spinach leaves to pasta sauces (at the end of cooking), lasagna, soups, omelettes and sandwiches.

Also eat: Swiss chard, kale, collards, beet greens, dandelion greens, rapini, arugula, romaine lettuce.


So far, two large studies suggest that having higher blood levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) – the two omega-3 fatty acids in oily fish – reduce the risk of diabetes by 32 per cent. Omega-3 fats are thought to improve how the body uses insulin.

Include at least six ounces of oily fish in your diet each week. If you don't eat fish, consider taking a daily fish-oil supplement that provides 500-600 mg of DHA + EPA (combined). DHA supplements made from algae are available for vegetarians.

Also eat: Arctic char, trout, sardines, herring, anchovies, mackerel (like salmon, all are low in mercury).

Ground flaxseed

This tiny seed is also a rich source of omega-3's, in particular alpha linolenic acid (ALA). Higher intakes of ALA have been tied to protection from Type 2 diabetes.

Add ground flaxseed (a.k.a. milled flaxseed or flax meal) to smoothies, protein shakes, yogurt, hot cereal, stews, meatloaf, burgers and muffin and pancake batters. Include one to two tablespoons in your daily diet.

Also eat: chia seeds, hemp seeds, walnuts, walnut oil, canola oil, soybeans.


Drinking 3 to 4 cups of coffee (caffeinated and decaffeinated) per day is related to a 25-per-cent lower risk of Type 2 diabetes. Coffee's benefits may be due to chlorogenic acid, an antioxidant that dampens inflammation, reduces glucose absorption and improves insulin sensitivity. Coffee is also a source of magnesium.

If you drink coffee, add little, if any, sugar or use stevia to sweeten it.

Leslie Beck, a registered dietitian, is based at the Medisys clinic in Toronto. She can be seen every Thursday at noon on CTV News Channel's Direct (

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