Low-GI Vegan Diet: Benefits, Guidelines, and Recipes

With the growing interest in plant-based diets, many people are exploring the vegan lifestyle. However, concerns often arise about whether a vegan diet can provide all the necessary nutrients, especially for individuals with diabetes. This article explores the benefits of a low-glycemic index (GI) vegan diet, provides guidelines for following it, and offers recipe ideas.

Understanding Veganism

Veganism is a lifestyle that seeks to exclude all forms of exploitation and cruelty to animals for food, clothing, or any other purpose, according to the Vegan Society. People adopt a vegan lifestyle for various reasons, including animal welfare and environmental concerns. Nowadays, it has become considerably easier to "go vegan," with most of the produce needed for a healthy vegan diet readily available in regular supermarkets.

The Importance of a Well-Planned Vegan Diet

While most foods in a vegan diet are naturally beneficial, not all vegan diets are inherently healthy. Careful planning is crucial, especially for children, to ensure that the diet provides all the key nutrients necessary for good health. Research is essential before embarking on a vegan diet.

Addressing Nutritional Concerns

• Protein: Adequate protein intake is a common concern for new vegans. However, with proper planning, it is achievable. Nuts, seeds, and their butters are excellent sources of plant-based protein.
• Vitamin B12: Vitamin B12 is essential for healthy blood and a healthy nervous system. It is naturally found only in animal products. Vegans should consume B12-fortified foods at each meal or take a daily supplement containing at least 10 micrograms of B12.
• Calcium: Calcium is vital for strong bones, especially during growth until around age 25. Vegans can obtain calcium from fortified foods.
• Omega-3 Fatty Acids: Omega-3 fatty acids are beneficial for heart health, which is particularly important for people with diabetes who have an increased risk of heart disease. Vegan sources include flax seeds, chia seeds, and walnuts.
• Selenium: Selenium is an essential nutrient and a component of many enzymes. Since vegan sources can be challenging to find, a supplement may be considered.
• Iodine: Iodine is necessary for thyroid hormone production. Plant-based sources are unreliable, and many plant-based milks are not fortified, so supplementation may be necessary.
• Zinc: Zinc aids in fighting infection. Vegans should ensure adequate zinc intake through diet or supplements.

Low-GI Diet: An Overview

The low glycemic (low GI) diet revolves around the concept of the glycemic index (GI). The glycemic index (GI) is a measurement system that ranks foods according to their effect on your blood sugar levels. It was created in the early 1980s by Dr. David Jenkins, a Canadian professor. The rates at which different foods raise blood sugar levels are ranked in comparison with the absorption of 50 grams of pure glucose. Pure glucose is used as a reference food and has a GI value of 100.

The three GI ratings are:

Read also: Vegan Diet for Diabetes Management

• Low: 55 or less
• Medium: 56 to 69
• High: 70 or more

Foods with a low GI value are slowly digested and absorbed, causing a slower and smaller rise in blood sugar levels. On the other hand, foods with a high GI value are quickly digested and absorbed, resulting in a rapid rise and fall of blood sugar levels.

Factors Influencing GI Value

Several factors can influence the GI value of a food or meal:

• Type of sugar: The GI of sugar ranges from as low as 23 for fructose to up to 105 for maltose.
• Structure of starch: Foods with a higher amylose content (difficult to digest) will have a lower GI.
• Refinement of the carb: The more processed a food is, the higher its GI.
• Nutrient composition: Adding protein or fat to a meal can slow digestion and reduce the glycemic response.
• Cooking method: Generally, the longer a food is cooked, the faster its sugars will be digested and absorbed, raising the GI.
• Ripeness: The riper the fruit, the higher its GI.

Glycemic Load (GL)

The glycemic load (GL) rating was developed as a measure of how a carb affects blood sugar levels, taking both the type (GI) and quantity (grams per serving) into account.

The GL ratings are:

• Low: 10 or less
• Medium: 11 to 19
• High: 20 or more

The easiest way to aim for a GL under 100 is to choose low GI foods when possible and consume them in moderation.

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Benefits of a Low-GI Diet

Studies have shown that the low GI diet may result in weight loss, reduce blood sugar levels, and lower the risk of heart disease and type 2 diabetes. Good blood sugar control helps prevent and delay the onset of complications, including heart disease, stroke, and damage to the nerves and kidneys.

Research suggests that low GI diets reduce blood sugar levels in people with diabetes. A 2019 review of 54 studies concluded that low GI diets reduced hemoglobin A1C (a long-term marker of blood sugar control), body weight, and fasting blood sugar levels in people with prediabetes or diabetes.

Moreover, the low GI diet has been shown to reduce the risk of macrosomia, a condition in which newborns have a birth weight over 8 pounds and 13 ounces.

Studies have shown that the low GI diet may also have other health benefits:

• Improved cholesterol levels: A 2019 study showed that low GI diets reduce total cholesterol and LDL (bad) cholesterol.
• May help you lose weight: Some evidence from 2020 suggests that low GI diets can promote fat loss.
• May reduce the risk of cancer: Some research suggests that people who consume high GI diets are more likely to develop certain types of cancer.
• May reduce the risk of heart disease: Research has strongly associated high GI and GL diets with an increased risk of heart disease.

Plant-Based Diets and Type 2 Diabetes

The prevalence of type 2 diabetes is rising worldwide, especially in older adults. Diet and lifestyle, particularly plant-based diets, are effective tools for type 2 diabetes prevention and management. Plant-based diets emphasize legumes, whole grains, vegetables, fruits, nuts, and seeds and discourage most or all animal products.

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Cohort studies strongly support the role of plant-based diets in reducing the risk of type 2 diabetes. Evidence from observational and interventional studies demonstrates the benefits of plant-based diets in treating type 2 diabetes and reducing key diabetes-related macrovascular and microvascular complications.

The evidence does suggest that the type and source of carbohydrate (unrefined versus refined), fats (monounsaturated and polyunsaturated versus saturated and trans), and protein (plant versus animal) play a major role in the prevention and management of type 2 diabetes.

How Plant-Based Diets Reduce Insulin Resistance

Dietary choices are a key driver of insulin resistance, especially in an aging, more sedentary population. Plant-based diets are especially potent in preventing type 2 diabetes and have been associated with much lower rates of obesity, hypertension, hyperlipidemia, cardiovascular mortality, and cancer.

Evidence from Large Cohort Studies

Large cohort studies demonstrate that the prevalence and incidence of type 2 diabetes are significantly lower among those following plant-based eating patterns compared with omnivores and even semi-vegetarians. Those following plant-based diets tend to have lower body mass indices, which protects against type 2 diabetes.

The Adventist Health Study 2 examined disease prevalence by different eating patterns in an overall health-conscious cohort. Among nearly 61,000 individuals, the prevalence of type 2 diabetes decreased in a stepwise fashion with each reduction in animal products in the diet. The apparent protection of the vegan dietary pattern remained after adjustment for body mass index and other variables, with vegans having half the rate of type 2 diabetes compared with non-vegetarians.

Prospective studies of the same Adventist cohort demonstrate similar findings. In a cohort of 4384 Taiwanese Buddhists, vegetarian men had approximately half of the rate of diabetes, and vegetarian post-menopausal women had one-quarter the rate of diabetes, compared with their omnivorous counterparts, despite statistical adjustment for body mass index and other factors.

In the largest prospective study of plant-based eating patterns to date, Satija, et al., evaluated dietary choices and type 2 diabetes incidence in the Nurses' Health Study, Nurses' Health Study 2, and the Health Professionals Follow-up Study. Analysis of data from 4.1 million person-years of follow up revealed that those most adherent to the healthful plant-based dietary index had a 34% lower risk of developing diabetes compared with those least adherent. These associations were independent of body mass index and other diabetes risk factors.

Role of Fiber, Legumes, and Whole Grains

A whole-foods, plant-based eating pattern generally includes legumes, whole grains, fruits, vegetables, and nuts, and is high in fiber. All of these elements have been found to be protective against diabetes.

Malik et al., found that individuals in the highest quintile of animal protein consumption had a 13% increased risk of type 2 diabetes compared with those in the lowest quintiles. These authors also found that substituting 5% of energy intake from animal protein with vegetable protein was associated with a 23% reduced risk of type 2 diabetes.

In contrast, protein intake from plant sources offered protection against diabetes.

Clinical Trials Supporting Plant-Based Diets for Diabetes

As far back as the 1950s, studies have documented the effectiveness of employing a predominantly vegetarian diet to treat diabetes.

Barnard et al., performed the first major randomized clinical trial on diabetic patients treated purely with a plant-based (vegan) diet, comparing it to a conventional diet based on the 2003 American Diabetes Association (ADA) guidelines. The recommended vegan diet comprised approximately 10% of energy from fat, 15% from protein, and 75% from carbohydrates and consisted of vegetables, fruits, grains, and legumes. By the end of the trial, 43% of the vegan group and 26% of the ADA group participants reduced their diabetes medications. Excluding those who changed medications, hemoglobin A1c fell 1.23 points in the vegan group compared with 0.38 points in the ADA group. Body weight decreased 6.5 kg in the vegan group and 3.1 kg in the ADA group.

When these individuals were followed for a total of 74 weeks, a sustained and equivalent weight loss was noted in both groups, but there was a significant absolute reduction in hemoglobin A1c of −0.40 points in the vegan group versus +0.01 in the ADA group. In addition, there was a significant reduction in total cholesterol and LDL cholesterol in the vegan versus ADA diet, respectively.

To evaluate this question, Anderson et al., performed a study on a metabolic ward enrolling lean men with type 2 diabetes who were taking insulin, and placing them on high-carbohydrate, high-fiber (HCF) diet (< 10% calories from fat, 70% from carbohydrates, and 65 g of fiber/day). Half of the participants were able to discontinue insulin, and the remainder were able to significantly reduce their insulin; overall, the average insulin dose decreased from 26 units on the baseline (control) diet to 11 units on the HCF diet.

A 2014 review and meta-analysis of controlled clinical trials of vegetarian diets in the treatment of type 2 diabetes found a significant reduction in hemoglobin A1c of −0.39 points compared to control diets. This effect is approximately half of that seen with the addition of the first-line oral hypoglycemic agent, metformin.

A more recent randomized controlled trial conducted in Korea compared a brown-rice-based vegan diet with a conventional diabetic diet in patients ages 30–70 years with type 2 diabetes. Participants assigned to the vegan diet were asked to eat brown rice, favor low-glycemic index foods (e.g., legumes, legumes-based foods, green vegetables, and seaweed), and avoid polished/white rice, processed food made of rice flour or wheat flour, and all animal food products. Hemoglobin A1c levels decreased by 0.5 points in the vegan group compared with 0.2 points in the conventional group.

The inclusion of individuals older than age of 60 in this trial, and in the majority of vegetarian trials mentioned in the meta-analysis above, supports recommending plant-based diets to all age groups with type 2 diabetes, including older adults.

Cardiovascular and Renal Benefits

Cardiovascular disease is the major cause of premature mortality in the diabetic population and many trials have demonstrated the benefits of plant-based diets in preventing and treating cardiovascular disease. In large cohort studies, vegetarian diets have been associated with significant reductions in ischemic heart disease incidence and mortality relative to omnivorous diets. Intervention trials of plant-based diets have also documented angiographic and clinical reversal of coronary artery disease.

Ornish, et al., randomized individuals with cardiovascular disease to usual care or lifestyle treatment that included a low-fat vegetarian diet in combination with moderate exercise, stress management, and smoking cessation. After 5 years, LDL levels in the lifestyle intervention group decreased 20% from baseline without lipid-lowering medications. In the lifestyle group, the average degree of coronary artery stenosis decreased over five years with a 7.9% relative improvement by year 5, compared to a 27.7% worsening in the usual care group. There was a 60% reduction in cardiac events in the lifestyle group compared with the usual care group.

Esselstyn, et al., examined the effects of making dietary changes alone, without other lifestyle interventions, on patients with established cardiovascular disease. The authors reported that in 11 patients with severe coronary artery disease who were compliant with a low-fat plant-based diet, 8 (73%) had documented regression of coronary artery disease on repeat angiogram after five years on the diet.

A literature review of plasma lipids and plant-based diets found that among different plant-based diets (i.e., lacto-ovo vegetarian, lactovegetarian, and vegan), populations following vegan diets had the lowest cholesterol concentrations. This review also found that plant-based diets are associated with up to a 35% reduction in serum LDL cholesterol, whereas interventions allowing small amounts of lean meat demonstrated less dramatic reductions in total cholesterol and LDL levels.

Among intervention trials of plant-based diets, a recent systematic review and meta-analysis found that those adopting a fully or mostly plant-based diet had significant reductions in C-reactive protein and other obesity-related inflammatory biomarkers compared to those following control, non-plant-based diets.

Chronic kidney disease rates increase with age, and among those older than 60 years, renal impairment is more common in diabetic versus nondiabetic patients.

Chen, et al., found that in individuals with chronic kidney disease, every 33% increase in plant to total protein consumption was associated with a significant 23% lower mortality risk.

General Guidelines for a Low-GI Vegan Diet

The basic principle of the low glycemic index diet is to eat foods that will be metabolized slowly and with a moderate effect on blood glucose levels.

• Pair Vegan Proteins with Complex Carbohydrates: Plant-based proteins should be paired with complex carbohydrates. A complex carbohydrate is more difficult for the body to digest, so it will take longer for the sugars inside of it to become reflected as glucose in the blood. Animal fats can also be substituted for plant-based fats. Avocado can often be substituted for butter, for example.
• Prioritize Medium to Low Glycemic Index Carbohydrates: Even some high glycemic index foods, like starchy bread and other vegan products, can be paired with low glycemic index proteins and leafy greens. The result of a dish made with starchy vegan options and less starchy vegan options will be a lower glycemic index.
• Include a Balance of Fats, Proteins, and Fibers in Your Vegan Meals: Fibers can provide a filling option with very low glycemic index values while remaining within the vegan diet.

Foods to Include in a Low-Glycemic Vegan Diet

• Grains: Whole grains, like quinoa, brown rice, oatmeal, and barley.
• Beans & Legumes: Fiber-rich beans like chickpeas, black beans, or lentils.
• Soy: Edamame, tofu, and soy protein powders.
• Fruits: Apples, pears, apricots, peaches, plums, berries.
• Nuts and Seeds: Walnuts, almonds, pecans, nut butter, chia seeds, flax seeds, and pumpkin seeds.
• Vegetables: Non-starchy vegetables like leafy greens, asparagus, broccoli, Brussels sprouts, mushrooms, and cauliflower.
• Healthy Fats: Avocado, grapeseed oil, olive oil.
• Starchy Vegetables: Corn, peas, winter squash, and potatoes (paired with lower glycemic foods along with fat and protein).

Foods to Limit on a Low-Glycemic Vegan Diet

• Refined Grains: White bread and rolls, white rice, enriched white pasta, pancakes, waffles, and chips.
• Pastries: Cookies, cakes, and candy.
• Sugary Drinks: Soft drinks, kombucha, sweetened tea, and energy drinks.
• Cereals and Cereal Bars: Sugar-coated and refined cereals, some instant oatmeals, granola bars, cereal bars.
• Agave: Overconsumption of agave can lead to excess fat stored in the liver.

Sample Low-GI Vegan Meal Plan

This sample meal plan provides ideas for a week on a low-GI vegan diet. Adjust it based on your own needs and preferences.

• Monday
  • Breakfast: Oatmeal made with rolled oats, milk, pumpkin seeds, and chopped, fresh, low GI fruit
  • Lunch: Minestrone soup with a slice of whole grain bread
  • Dinner: beef stir-fry with vegetables, served with long grain rice
• Tuesday
  • Breakfast: whole grain toast with avocado, tomato, and smoked salmon
  • Lunch: minestrone soup with a slice of whole grain bread
  • Dinner: grilled fish served with steamed broccoli and green beans
• Wednesday
  • Breakfast: omelet with mushrooms, spinach, tomato, and cheese
  • Lunch: salmon, ricotta, and quinoa cups with a salad
  • Dinner: homemade pizzas made with whole wheat bread
• Thursday
  • Breakfast: smoothie with berries, milk, Greek yogurt, and cinnamon
  • Lunch: chicken pasta salad made with whole wheat pasta
  • Dinner: homemade burgers with beef patties and vegetables on whole wheat rolls
• Friday
  • Breakfast: fruity quinoa porridge with apple and cinnamon
  • Lunch: toasted tuna salad sandwich on whole wheat bread
  • Dinner: chicken and chickpea curry with basmati rice
• Saturday
  • Breakfast: eggs with smoked salmon and tomatoes on whole grain toast
  • Lunch: whole grain wrap with egg and lettuce
  • Dinner: grilled lamb chops with greens and mashed pumpkin
• Sunday
  • Breakfast: buckwheat pancakes with berries
  • Lunch: brown rice and tuna salad
  • Dinner: beef meatballs served with vegetables and brown rice

Low-GI Vegan Snack Ideas

• A handful of unsalted nuts
• A piece of fruit like apple slices with nut butter, almond butter, or peanut butter
• Carrot sticks with hummus
• A cup of berries or grapes served with a few cubes of cheese
• Unsweetened Greek yogurt with sliced almonds
• A hard-boiled egg
• Low GI leftovers from the night before

Easy Meal Recipes for a Low-Glycemic Vegan Diet

• Breakfast: Overnight Oats With Almond Butter, Almond Milk, Apples, and Cinnamon
  • ½ cup rolled oats
  • ½ cup almond or soy milk
  • 1 tsp. chia seeds
  • ½ tsp. cinnamon
  • 1 tbsp almond butter
  • ¼ cup chopped apples
  • Combine the oats, almond milk, chia seeds, and cinnamon in a mason jar or bowl. Stir well to combine all the ingredients. Cover tightly and place it in the refrigerator to chill overnight. In the morning, stir in the almond butter and finely chopped apples.
• Lunch: Lentil Soup with Greens and Whole Grain Crackers
  • 1 cup lentil soup
  • ½ cup chopped kale or Swiss chard
  • Whole-grain crackers
  • Heat the soup in a medium saucepan. Add the chopped greens to wilt. Serve with crackers on the side.
• Dinner: Sesame Ginger Tofu Stir Fry
  • 2 tsp. peanut oil
  • 1 tsp. toasted sesame oil
  • ¼ cup chopped onion
  • 1 tsp. minced garlic
  • 1 tbsp. sliced ginger
  • 1 cup broccoli florets
  • ½ cup carrots
  • 1 sliced portabella mushroom (UV grown)
  • 3 oz. firm tofu, pressed and cut into cubes
  • ½ cup shredded bok choy
  • 2 tsp. soy sauce
  • ½ cup brown rice
  • In a large skillet heat the peanut oil and sesame oil over medium-high heat. Add the onion and stir fry it for 2-3 minutes until just translucent, being careful not to burn it. Add the garlic and ginger and cook for 1 minute. Stir in the broccoli, carrots, and sliced mushroom, and stir fry for about 4 minutes. Remove the vegetables from the skillet and add the tofu. Cook until it begins to brown on all sides. Add the vegetables back to the pan and add the bok choy to wilt. Stir in the soy sauce and toss to coat. Serve over brown rice.

Tips for Following a Low-Glycemic Vegan Diet

• Focus on eating protein at each meal: Protein will help slow the absorption of those higher carbohydrate/ higher GI foods. Foods like tofu, beans, nuts, and nut butter are good choices.
• Aim for at Least 5 Grams of Fiber at Each Meal: Fiber will help keep you full longer and will also slow the absorption of higher GI foods.
• Eat a Variety of Food: It’s easy to get into a rut, especially for breakfast and lunch, but do your best to mix it up a bit so you get a variety of nutrients every day. This will help ensure you get all the nutrients your body needs.

Potential Drawbacks of the Low-GI Diet

Although the low GI diet has several benefits, it also has a number of drawbacks.

First, the GI doesn’t provide a complete nutritional picture. It’s important to also consider the fat, protein, sugar, and fiber contents of a food, regardless of its GI.

Another drawback is that the GI measures the effect of a single food on blood sugar levels. However, most foods are consumed as part of a larger mixed meal, making the GI difficult to predict in these circumstances.

Lastly, GI doesn’t take into account the number of carbs you eat, an important factor in determining their effect on your blood sugar levels.

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