Plant-Based Diets: Nutritious Or Nutritionally Negligent?

A plant-based diet is one that focuses on foods derived from plants, including fruits, vegetables, whole grains, nuts, seeds, oils, legumes, and beans. It does not necessarily mean that a person is vegetarian or vegan and never eats meat or dairy. Plant-based diets are typically associated with a range of health benefits, such as lower body mass index (BMI), lower rates of obesity, diabetes, and heart disease, and reduced risk of certain types of cancer. However, it is important to ensure adequate intake of certain nutrients, such as vitamin B12, vitamin D, iron, and omega-3 fatty acids, which may be lower in plant-based diets.

Plant-based diets and weight management

Plant-based diets are associated with a lower body mass index and lower rates of obesity, diabetes, and heart disease than diets that include meat. Research suggests that plant-based diets are effective for weight management and weight loss, even without exercise or calorie counting.

Plant-based diets are high in fibre, complex carbohydrates, and water content from fruit and vegetables. This helps people feel fuller for longer and increases energy use when resting. Replacing high-fat foods with fruits, vegetables, whole grains, and legumes naturally reduces calorie intake.

A 2018 study found that a plant-based vegan diet was effective for treating obesity. In the study, researchers assigned 75 people who were overweight or obese to either a vegan diet or a continuation of their regular diet, which contained meat. After four months, only the vegan group showed a significant weight loss of 6.5 kilograms (14.33 pounds). The plant-based vegan group also lost more fat mass and saw improvements in insulin sensitivity, whereas those who consumed a regular diet with meat did not.

A 2009 study of more than 60,000 people also found that vegans had the lowest average BMI, followed by lacto-ovo vegetarians (those who eat dairy and eggs) and pescatarians (people who eat fish but no other meat). The group with the highest average BMI were non-vegetarians.

In addition to supporting weight management, plant-based diets offer a range of other health benefits. These include a reduced risk of heart disease, stroke, diabetes, and certain types of cancer. Plant-based diets are also associated with improved insulin sensitivity and reduced insulin resistance, which can help prevent and manage diabetes.

While plant-based diets offer many health benefits, it is important to ensure adequate intake of certain nutrients. Vitamin B12, for example, is an essential nutrient for blood and cell health and is present in many animal products but not in many plant-based foods. People following a vegan or vegetarian diet may need to take a B12 supplement or consume B12-fortified foods.

Iron is another nutrient to consider, as it has lower bioavailability in plants than in meat. Combining citrus and other vitamin C sources with plant-based sources of iron can help increase absorption.

Additionally, some people may have concerns about getting enough protein from a plant-based diet. However, there is a wide variety of plant-based sources of protein, including beans, lentils, chickpeas, and nuts. Consuming proteins from a variety of food sources can help provide all the necessary amino acids for good health.

If you want to make the switch to a plant-based diet, you can start by gradually reducing your meat and dairy intake. Eating an entirely plant-based meal once a week or swapping out one animal product for a plant-based alternative can be a great place to start.

It is also important to note that just reducing or eliminating animal products does not automatically make a plant-based diet healthy. It is crucial to reduce or avoid unhealthy foods, such as sugary foods, refined carbohydrates, processed vegan and vegetarian alternatives, and fatty or deep-fried foods.

Plant-based diets offer a range of health benefits, including weight management and weight loss. They are typically high in fibre and complex carbohydrates, which can help people feel fuller for longer and increase energy use. In addition, plant-based diets are associated with a reduced risk of obesity, diabetes, heart disease, and certain types of cancer. However, it is important to ensure adequate intake of certain nutrients, such as vitamin B12 and iron, when following a plant-based diet.

Plant-based diets and heart health

A plant-based diet is a powerful way to achieve good health and can be less expensive than an omnivorous diet. Research has shown that a plant-based diet can prevent and reverse heart disease, improve cholesterol, and lower blood pressure.

A plant-based diet involves consuming mostly or only foods that come from plants. This includes fruits, vegetables, whole grains, nuts, legumes, and sometimes animal products, depending on the individual. A plant-based diet focuses on healthful whole foods rather than processed foods.

Health Benefits of a Plant-Based Diet

People who eat plant-based diets tend to have a lower body mass index (BMI) and lower rates of obesity, diabetes, and heart disease than those who eat meat. Plant-based diets are high in fiber, complex carbohydrates, and water content from fruits and vegetables, which can help keep people feeling fuller for longer and increase energy use when resting.

Research has shown that a plant-based diet can be an effective treatment for obesity. A 2018 study found that a plant-based vegan diet was effective in treating obesity, with participants losing a significant amount of weight, fat mass, and seeing improvements in insulin sensitivity. A 2009 study of over 60,000 people also found that vegans had the lowest average BMI, followed by those who ate dairy and eggs, then fish, and finally non-vegetarians, who had the highest average BMI.

A 2019 study from the Journal of the American Heart Association found that middle-aged adults who ate diets high in healthful plant foods and low in animal products had a lower risk of heart disease. A plant-based diet can also help prevent and manage diabetes by improving insulin sensitivity and reducing insulin resistance. Of the 60,000 people studied in 2009, only 2.9% of people on a vegan diet had type 2 diabetes, compared to 7.6% of those eating a non-vegetarian diet.

Nutritional Considerations

When transitioning to a plant-based diet, it is important to ensure you are getting enough of certain nutrients. Vitamin B12 is essential for blood and cell health and is present in many animal products but not in many plant-based foods. It is recommended that people who eat vegan or vegetarian diets consider taking a B12 supplement or consume products fortified with B12, such as some cereals, plant-based milk, and nutritional yeast.

Iron is another nutrient to consider, as it has lower bioavailability in plants than meat. It is important to combine citrus and other vitamin C sources with plant-based sources of iron to increase absorption.

Some people may also be concerned about getting enough protein from a plant-based diet. However, there is a wide variety of plant-based sources of protein, including beans, lentils, chickpeas, tofu, tempeh, and seitan. Consuming proteins from a variety of food sources can help provide all the necessary amino acids for good health.

Finally, some people following a plant-based diet may wish to consider taking an omega-3 supplement, as the body is slow and inefficient at converting ALA, found in plant-based foods, to EPA and DHA, the two primary omega-3 fatty acids. Vegetarians exhibit lower levels of DHA and EPA in blood and tissue, which may increase inflammation and memory difficulties.

A plant-based diet offers many health benefits, including improved weight management and a reduced risk of heart disease and diabetes. It is important to ensure you are getting enough of certain nutrients, such as vitamin B12, iron, and omega-3 fatty acids, when following a plant-based diet.

Plant-based diets and diabetes

Plant-based diets are effective in the prevention and treatment of type 2 diabetes. Plant-based diets are eating patterns that emphasise legumes, whole grains, vegetables, fruits, nuts, and seeds and discourage most or all animal products.

Benefits of Plant-Based Diets for Diabetes

Plant-based diets are associated with a reduced risk of developing type 2 diabetes and are highly effective in its treatment. Diets that emphasise whole grains, vegetables, fruits, and legumes and exclude animal products improve blood glucose concentrations, body weight, plasma lipid concentrations, and blood pressure and play an important role in reducing the risk of cardiovascular and microvascular complications.

Mechanisms of Plant-Based Diets

Insulin resistance and subsequent impairment in β-cell function are the hallmarks of type 2 diabetes pathophysiology. Plant-based eating patterns are beneficial for patients with diabetes by improving insulin sensitivity and improving body weight. Insulin resistance is caused by lipid accumulation within muscle and liver cells that typically begins many years before the diagnosis of type 2 diabetes. Plant-based diets may also improve β-cell function.

Weight management plays an important role in improving insulin sensitivity and glycemic control and reducing cardiovascular disease (CVD) risk factors. Excess body weight is associated with risk of CVD and all-cause mortality among people with type 2 diabetes. Individuals following vegetarian, especially vegan, diets have lower mean BMIs, compared with nonvegetarians. Population studies have revealed that body weight increases progressively with increased meat consumption.

Plant-Based Diets for Macrovascular and Microvascular Complications of Diabetes

The effects of plant-based diets on glycemia, body weight, plasma lipids, and blood pressure collectively reduce the risk of CVD, the leading cause of morbidity and mortality in diabetes patients. CVD encompasses coronary heart disease, cerebrovascular disease, and peripheral arterial disease. A meta-analysis of 9 randomised controlled trials in patients with type 2 diabetes (N = 664), comparing vegetarian interventions with control diets, showed significant improvements in CVD risk factors, including lipids, blood pressure, glycemic control, body weight, and abdominal adiposity.

Plant-Based Diets Compared to Other Dietary Approaches for Type 2 Diabetes

Plant-based diets may provide improvements for diabetes without intentional caloric reduction and may do so independently of weight loss.

Very-low-calorie diets and metabolic surgery

Reversal of insulin resistance and β-cell dysfunction with associated reductions in pancreatic and hepatic triacylglycerol stores has been demonstrated in patients with type 2 diabetes with very-low-calorie diets (600 kcal/d) or bariatric surgery. These interventions are not free from clinical challenges or risk. Very-low-calorie diets require medical management by trained practitioners and may only be appropriate in select patients. Further, the long-term sustainability of such diets is limited; they are frequently followed by progressive weight gain. Adverse effects of metabolic surgery include mortality (rates 0.1–0.5%), dumping syndrome, nutritional deficiencies, increased risk of depression, and substance abuse.

Mediterranean and Dietary Approaches for Stopping Hypertension

Mediterranean and Dietary Approaches for Stopping Hypertension (DASH) diets both emphasise the intake of plant-based foods with controlled portions of animal products. Mediterranean diets have been tested for the prevention and treatment of diabetes. Like a plant-based diet, Mediterranean diets emphasise the consumption of fruits, vegetables, whole grains, and legumes, and reduce meat, refined grains, and sugar, while allowing modest amounts of animal products.

Low-carbohydrate eating pattern

Low-carbohydrate diets cause weight loss in overweight individuals, although they are no more effective for weight loss than plant-based diets or other dietary approaches in 1-year comparisons. The common idea that low-carbohydrate diets suppress appetite was challenged in a 2021 metabolic-ward study. Twenty young overweight adults were assigned to a low-fat, vegan diet (10% fat, 75% carbohydrate) or a low-carbohydrate diet (76% fat, 10% carbohydrate) for 2 weeks, then switched to the opposite diet for an additional 2 weeks. The vegan diet led to a much greater drop in calorie intake; energy intake was 689 (± 73) kcal/d lower during the vegan phase, compared with the low-carbohydrate phase.

Plant-based diets and cancer

Plant-based diets are defined by their focus on foods derived from plants, including fruits, vegetables, nuts, seeds, oils, whole grains, legumes, and beans. This does not necessarily imply that the dieter is vegetarian or vegan, but rather that they are choosing to eat more of their food from plant sources. Plant-based diets have been shown to have a positive impact on health, reducing the risk of heart disease, metabolic syndrome, diabetes, certain cancers, and depression.

Research suggests that a plant-based diet may reduce the risk of developing certain cancers. The American Cancer Society estimates that 25% of cancer cases could be prevented with diet and nutrition alone. Phytochemicals, compounds found in plant-based foods, are thought to be responsible for this protective effect. Phytochemicals protect the body from damage, decrease inflammation, and interrupt processes in the body that encourage cancer production.

Two of the most beneficial phytochemicals are:

• Antioxidants: These neutralise the cell-damaging processes caused by radiation, viruses, and exposure to other chemicals. Antioxidant-rich foods include dark chocolate, apples, avocados, artichokes, red cabbage, tea, coffee, nuts, and grains.
• Carotenoids: These fat-soluble compounds are found in many fruits, grains, oils, and vegetables, including carrots, sweet potatoes, squash, spinach, apricots, green peppers, and leafy greens. They have been linked to a reduced risk of heart disease, cancer, macular degeneration, and cataracts.

Plant-based diets are also high in fiber, which has been shown to lower the risk of breast and colorectal cancer. A study found that young women who ate the most fiber-rich diets were 25% less likely to get breast cancer later in life. Another study found that each 10 grams of daily fiber could lower the risk of colorectal cancer by 10%.

Plant-based diets are also beneficial for those who have already been diagnosed with cancer. The American Institute for Cancer Research found that for every 10-gram increase in fiber in the diet, survival rates after a cancer diagnosis improved by 13%.

Plant-based diets are a healthy choice for those looking to reduce their risk of cancer. For those who have already been diagnosed, a shift towards a plant-based diet may improve survival rates.

Plant-based diets and vitamin B12

Vitamin B12 is an essential nutrient that is not made by plants. It is not found in unfortified plant-based foods, and so vegetarians and vegans must take particular care to consume enough vitamin B12. It is mainly found in meat, eggs, and dairy products, and so a vitamin B12 deficiency is more likely in those following a plant-based diet.

Vitamin B12 plays an important role in a person's health. It is integral to the formation of red blood cells, the protection of the nervous system, the synthesis of DNA, and providing the body with energy. A vitamin B12 deficiency can have severe consequences, including fatigue, dizziness, weakness, tingling in the hands and feet, depression, and nerve damage.

Vegetarians and vegans can get their vitamin B12 from fortified plant-based milks, fortified cereals, and nutritional yeast. Seaweed, algae, and certain mushrooms also contain small amounts of vitamin B12, but more research is needed to assess the amounts and bioavailability.

The recommended daily allowance of vitamin B12 depends on a person's age:

• Adults and teenagers: 2.4 micrograms per day
• Children between 9 and 13 years old: 1.8 micrograms per day
• Children between 4 and 8 years old: 1.2 micrograms per day
• Toddlers between 1 and 3 years old: 0.9 micrograms per day
• Infants between 7 and 12 months old: 0.5 micrograms per day
• Babies less than 6 months old: 0.4 micrograms per day
• Pregnant women: 2.6 micrograms per day
• Breastfeeding women: 2.8 micrograms per day

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