The information in this article is for informational purposes only. Consult your healthcare provider before making any significant changes to your diet. This is particularly important if you have a medical condition, are taking medications, or are pregnant.
Can plant-based diets not only improve your chances to live longer but help you live a better life now? What does current research tell us about plant-based diets and their effects on disease prevention, physical, and mental health?
In this article, we explore how plant-based diets can be used to improve the health and wellness of persons struggling with a variety of conditions as well as those who are looking to optimize their health and well-being.
What are plant-based diets?
Plant-based diets are an umbrella term describing a variety of nutrition patterns that minimize animal products or exclude animal products entirely.
A well-constructed plant-based diet consists mostly of minimally processed plants such as fresh fruits, vegetables, nuts, seeds, whole grains, beans/ legumes, herbs and spices, and may include plant-based oils such as olive oil.
Plant-based diets are defined by the American Cancer Research Institute (2022) as including the following patterns:
- Flexitarian – plant dominant but includes various animal products but in limited quantities.
- Pescatarian – plant dominant but includes fish, eggs, dairy, excludes other forms of meat.
- Vegetarian – plant dominant but includes eggs and dairy products, excludes all forms of meat.
- Vegan – 100% plant-based, excludes all animal products.
Other plant-based diet patterns include (Harvard, 2018; Magkos et al., 2020):
- Mediterranean – plant dominant, emphasizes seafood as a predominant animal protein source, allows for but limits dairy, poultry, and red meat.
- DASH diet – plant dominant, emphasizes lean animal proteins such as poultry, fish, and low-fat dairy, while limiting red meat, sodium, and sweets.
- Nordic diet – plant dominant, emphasizes local seasonal foods, lean animal proteins including fish, game meats, low-fat dairy, free range eggs, yogurt, cheese, canola oil, and minimizes processed foods.
What are some of the health benefits of plant-based diets?
Plant-based dietary patterns are associated with a wide variety of positive health effects when compared to the standard American diet (Satija et al., 2017).
Reduction in cardiovascular disease risk
Mediterranean diets supplemented with olive oil or nuts reduced the risk of a cardiovascular event (such as heart attack, stroke, or death related to a cardiovascular cause) by approximately 30% compared to the control group who was simply instructed to follow a low-fat diet (Estruch et al., 2018).
The DASH diet demonstrated a reduction in both systolic blood pressure (reduced by approximately 5-7 points) and diastolic blood pressure (reduced by approximately 3-4 points) with a high level of evidence in a systematic review comparing it to other various dietary patterns (Schwingshackl et al., 2019). This reduction proved superior to blood pressure lowering effects of other dietary interventions including Mediterranean, Nordic, vegetarian, and other tested diet patterns.
As healthy plant-based foods increase in the diet, coronary heart disease risk decreases. This is according to the Journal of the American College of Cardiology (Satija et al., 2017) in a review involving hundreds of thousands of participants studied over a period exceeding 20 years. The foods associated with a 25% decrease in heart disease risk included:
- Whole grains,
- Fruits/vegetables,
- Nuts/legumes,
- Oils,
- Tea/coffee
Perhaps not surprisingly, the same review found that unhealthy plant foods increased the risk of coronary heart disease. These foods included juices/sweetened beverages, refined grains, potatoes/fries, and sweets.
Vegetarian and vegan diets were similarly noted to reduce the risk of heart disease by approximately 20% in pooled data from more than 800,000 study participants (Dybvik, J. S., Svendsen, & Aune, 2022). Vegan diets were slightly more effective than vegetarian diets in reducing the risk of heart disease.
Perhaps most interesting of all, in a recent systematic review of studies evaluating vegetarian, vegan, and whole-food minimally processed plant-based diets’ effects on heart disease and diabetes, researchers noted that such diets demonstrated the potential ability to halt and even reverse heart disease and diabetes progression (Remde, DeTurk, Almardini, Steiner, & Wojda, 2022). The researchers note further research is needed to validate these findings.
Reduced risk of diabetes and diabetes-related complications
Diabetic patients or those at risk of diabetes frequently fear high-carbohydrate foods such as whole grains, beans/ legumes, brown rice, etc. However, plant-based diets have repeatedly demonstrated their potential to prevent diabetes or reduce the risk of complications from diabetes.
The Journal of Geriatric Cardiology published an analysis of plant-based diets as they relate to diabetes (McMacken & Shah, 2017). The researchers concluded that whole-food plant-based diets consisting of beans/ legumes, fruits, vegetables, nuts, and whole grains and no animal products or refined grains were effective in both treating and preventing diabetes.
Researchers noted that whole-food plant-based diets were effective at improving vascular health in both large and small blood vessels for diabetic patients (McMacken & Shah, 2017).
A whole food plant-based diet superior to diabetic diet in studies
In a randomized-controlled trial lasting 12 weeks, a vegan diet centered on brown rice, legumes, and vegetables outperformed a standard recommended diabetic diet in lowering A1C levels (Lee et al., 2016).
The Journal of the American Diabetes Association (ADA) similarly published research showing a vegan diet outperforming the ADA’s own diet in lowering A1C levels in diabetic participants (Bernard et al., 2006).
The Mediterranean diet appears to reduce the risk of developing diabetes, with adherents experiencing a 19-23% reduction in developing diabetes versus control groups as noted in a review published in the British Medical Journal (Esposito et al., 2015).
A high-carbohydrate plant-based diet improved diabetes status
In a fascinating randomized-controlled trial published by the Journal of the American Medical Association, 244 diabetics were randomized into two groups, with the intervention group consuming a high carbohydrate (75%), low fat (10%), moderate protein (15%) vegan diet consisting of vegetables, whole grains, legumes, and fruit. The control group was not asked to make any changes (Kahleova et al, 2020). The study ran 16 weeks.
Participants following the high carbohydrate plant-based diet lost on average 14 lbs, improved glucose levels, reduced insulin concentrations and led to reductions in fat levels in the muscle tissue and liver tissue (Kahleova et al., 2020). Even more interesting, participants were NOT instructed to limit caloric intake, demonstrating plant-based diets and their ability to promote satiety.
The American Diabetes Association 2017 Clinical Guidelines note that a variety of plant-based diets including the Mediterranean diet, DASH diet, and plant-based diets are acceptable for the management of prediabetes and diabetes (McMacken & Shah, 2017).
Weight loss and weight management
As already noted above, participants placed on a whole food plant-based diet with high carbohydrates and low fat lost an average of 14 lbs in 16 weeks without being asked to restrict their calorie intake (Kahleova et al., 2020).
Participants on a healthy plant-based diet ate till full and STILL lost weight!
This mirrors research in the “BROAD study” in which participants randomized into a whole food plant-based diet group lost an average of 23 lbs at 6 months…this without being asked to count or restrict calories!! (Wright, Wilson, Smith, Duncan, & McHugh, 2017).
Participants were told to simply eat whole grains, legumes, vegetables and fruits along with potatoes and pasta while avoiding high-calorie plant foods such as nuts, oils and also told to avoid all animal products. The potential benefits for people struggling with overweight and obesity of being able to eat till satiated while still producing weight loss is profound (Wright et al., 2017).
Even more important perhaps, participants in the plant-based diet intervention group rated their quality of life both physically and mentally as higher at 6 months (Wright et al., 2017). In other words, eating a whole-food plant-based diet did not lead to feelings of deprivation or despair.
Non-vegan plant-based diets also effective at weight management
In multiple large prospective studies of thousands of participants, increased consumption of whole grains, fruits/vegetables, nuts/legumes, vegetable oils, tea/coffee was protective against weight gain over a 10-20 year period (Magkos et al., 2020). Unhealthy plant foods however predicted greater obesity and weight gain.
The journal “Current Obesity Reports” notes that Mediterranean diets show strong evidence in their ability to treat and prevent obesity/ promote weight loss, reduce inflammation, and reduce visceral fat (Muscogiuri et al., 2022). Results have proven superior to general low-fat diet control groups.
However, it must be acknowledged that the best results came from calorie-restricted Mediterranean diet patterns paired with activity. This is in contrast to unrestricted low fat 100% plant-based diet interventions described above.
Plant-based diets and cancer
Cancer prevention
A review published in the Journal of the American Medical Association Oncology reviewed keto diets and whole food plant-based diets and noted that the cumulative available evidence supports whole food plant-based diets for reduction of cancer risk (Shah & Iyengar, 2022).
This finding is echoed by a report published in Current Nutrition Reports which notes that while site-specific cancer prevention findings have been inconsistent, overall cancer prevalence appears to be consistently lower in those consuming plant-based diet patterns (DeClercq, Nearing, & Sweeney, 2022). This finding has been repeated across numerous large and long-term population studies (DeClarcq et al., 2022).
It is believed the protection reducing the risk of cancer development that comes from plant-based diets stems from reductions in insulin growth-like factor 1, presence of various compounds (phytochemicals) found in plant-based foods, fiber, and stimulation of butyrate production in the gut (a healthy fatty acid produced by our gut microbes when breaking down fiber) (Shah & Iyengar, 2022).
The same researchers note however a lack of significant research for any diet pattern following a cancer diagnosis in terms of therapeutic potential for cancer treatment (Shah & Iyengar, 2022).
Cancer survivorship
Echoing the researchers above, a research review published in Current Nutrition Reports notes that diet and post-cancer diagnosis prognosis research is suggestive that plant-based diets may improve outcomes in survival for certain cancers but the research is inconclusive at this time and findings have not demonstrated high levels of consistency (Hardt, Mahamat-Saleh, Aune & Schlesinger, 2022).
Whole grains and fiber intake were associated with improved colorectal cancer survivorship (Hardt et al., 2022). Fruit, vegetables, fiber, and soy-isoflavones were associated with improved breast cancer survival rates. For prostate cancer, increased consumption of vegetables was linked to improved outcomes (Hardt et al., 2022).
Feel better! An improved sense of wellbeing
The British Medical Journal conducted a review of research on plant-based diets for diabetics and concluded that plant-based diets are linked to improved sense of emotional and physical wellbeing, reductions in depression, improved quality of life, in addition to improvements in various health markers (Toumpanakis, Turnbull, & Alba-Barba, 2018).
Similarly, adherence to a Mediterranean diet pattern was linked to a 32% reduction in rates of depression in an analysis of nine studies (Psaltopoulou et al., 2013). Interestingly, as adherence to the diet pattern increased, reductions in depression likewise increased, showing a “dose effect.”
In a 12-week randomized controlled trial, clinically depressed patients in the intervention group were put on a Mediterranean diet compared to a control group who just received social report (Jacka et al., 2017).
The intervention group consuming the Mediterranean diet saw substantial improvements in their depression, with 10 out of 31 participants achieving full remission of depression (versus the control group with only 2 out of 25 improving to that extent).
Are there any risks to plant-based diets?
According to the Journal of the Academy of Nutrition and Dietetics, more restrictive plant-based diets such as vegetarian and vegan diets can be safe and nutritionally sound when they are well-planned (Melina, Craig, & Levin, 2016). However, there are some precautions that must be taken to prevent harm from nutritional deficiencies. As such, it is very important to discuss such diets with your healthcare provider.
Persons interested in consuming all or mostly plant-based diets such as vegetarian and vegan diets must supplement with vitamin B12 as the only consistent/ reliable dietary source of B12 in the diet is meat (Melina et al., 2016). Insufficient vitamin B12 can lead to potentially irreversible nerve damage. Fortunately, supplementation is generally affordable and readily available.
Those consuming vegan or vegetarian diets must ensure they are consuming sufficient calcium, iodine, and vitamin D, as the risk of insufficient intake of these nutrients is elevated for vegans and vegetarians (Melina et al., 2016). Discussions around supplementation with your healthcare provider is advised for those consuming all or mostly plant-based diets.
Of lesser concern are protein, iron, zinc, and omega-3 intake levels as according to Journal of the Academy of Nutrition and Dietetics, intake of these nutrients are comparable/ generally sufficient in vegetarians and vegans assuming sufficient caloric intake (Melina et al., 2016).
Lastly, certain medications can be affected by changes in dietary patterns. Failure to discuss dietary changes with your healthcare provider prior to making these changes can be potentially dangerous.
Wrap-up
Plant-based diets ranging from moderate to no animal products paired with high amounts of whole foods such as beans/ legumes, fruits and vegetables, nuts/ seeds, whole grains, and potentially plant-based oils appear to have numerous benefits for various health outcomes.
From improving cardiovascular health, diabetic outcomes, and assisting with weight loss and management, to improving mental health and wellbeing, a shift towards whole food plant-based foods is consistent with current research findings for improved health and wellbeing.
Plant-based diets can be safe and nutritious but must be carefully planned when they restrict most or all animal foods such as meat. As such, any major dietary changes should first be discussed with your healthcare provider prior to making a significant change.
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