In the vast and often confusing world of nutrition, two diets have consistently captured public attention: the ketogenic diet and the plant-based diet. Social media platforms are flooded with testimonials, expert opinions, and passionate debates, making it difficult to discern the true benefits and drawbacks of each approach. This article aims to provide a comprehensive overview of these diets, drawing on expert insights and scientific evidence to help you make informed decisions about your dietary choices.
The Rise of Plant-Based and Keto Diets
While plant-based diets, particularly vegan diets, have a long history, their popularity has surged in recent years, fueled by social media trends and growing awareness of ethical and environmental concerns. The ketogenic, or keto, diet, characterized by its low-carbohydrate and high-fat composition, has also gained significant traction, especially in the last decade.
The abundance of conflicting information surrounding these diets can be attributed to various sources, including social media, well-meaning friends and family, and even the healthcare industry itself. As Shari Brown, RDN, a dietitian at UW Medicine Primary Care, notes, patients often receive contradictory advice from doctors, online sources, and their personal networks.
Plant-Based Diets: A Spectrum of Choices
The term "plant-based diet" encompasses a wide range of eating patterns, from those that heavily emphasize fruits, vegetables, and plant-based proteins while still including some animal products, to vegan diets that completely eliminate all animal products and byproducts.
Plant-Forward Approaches
Diets like the Mediterranean diet, which prioritize plants while incorporating lean proteins like fish and healthy fats, offer numerous benefits. These plant-forward approaches are rich in antioxidants, which combat inflammation, and promote heart health through their focus on healthy fats and proteins.
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Vegan Diets: A Complete Plant-Based Approach
Vegan diets, on the other hand, necessitate the exclusion of all animal products, requiring a greater reliance on whole grains, fruits, vegetables, beans, nuts, and seeds. This dietary pattern typically results in a high intake of fiber and antioxidants, as well as essential nutrients like potassium, magnesium, folate, and vitamins A, C, and E. While iron can be obtained from plant sources, it's important to note that the form of iron found in plants is not as readily absorbed as that found in animal foods.
Health Benefits of Plant-Based Diets
Regardless of whether they are fully vegan or incorporate some animal products, plant-based diets have been linked to a reduced risk of heart disease, type 2 diabetes, and certain cancers. They can also aid in weight management, improve digestive health, and potentially reduce inflammation throughout the body.
Potential Downsides of Plant-Based Diets
Despite their numerous advantages, plant-based diets also present certain challenges:
Adherence and Sustainability
While incorporating healthy animal products into a plant-based diet can make it easier to maintain, adhering to a strict vegan diet can be difficult, especially if the primary motivation is weight loss rather than ethical or environmental concerns. The need to consistently avoid certain foods can lead to recipe fatigue and make it challenging to sustain the diet long-term.
Nutrient Deficiencies
While a plant-based diet that includes some animal products can typically provide most essential nutrients, a vegan diet may require careful planning and supplementation to avoid deficiencies.
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Vitamin B12 is a primary concern for vegans, as it is primarily found in animal products. Supplementation with cyanocobalamin or sublingual methylocobalamin is often recommended. Other nutrients that may require attention include iron, zinc, calcium, vitamin D, and omega-3 fatty acids.
Plant-based sources of omega-3 fatty acids, such as flax, chia, and walnuts, contain ALA (alpha-linolenic acid), which has a low conversion rate to the more beneficial forms, DHA and EPA. Therefore, vegans may need to supplement with algae-based DHA.
Pregnancy and Lactation
Pregnant and breastfeeding women following a vegan diet may find it challenging to obtain sufficient protein and nutrients, potentially necessitating the temporary inclusion of some animal products to support the health of both mother and baby. Consulting with a healthcare professional is crucial to determine the safest and most appropriate course of action.
The "Healthy" Fallacy
It's important to remember that simply being plant-based does not automatically equate to being healthy. A diet consisting primarily of processed vegan foods like Oreos, Tater Tots, vegan pizza, and vegan burgers can be detrimental to overall health.
The Ketogenic Diet: Fueling on Fat
The ketogenic, or keto, diet stands in stark contrast to plant-based diets. It emphasizes a high intake of fats while drastically restricting carbohydrates. Contrary to popular belief, the keto diet is not necessarily high in protein; in fact, it is typically moderate or even low in protein, as excess protein can be converted into glucose, disrupting ketosis.
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Nutritional Ketosis: The Metabolic Goal
The primary goal of the keto diet is to induce a metabolic state called nutritional ketosis. By severely limiting carbohydrate intake, the body is forced to break down fatty acids for energy, producing ketones as an alternative fuel source for the brain.
Applications of the Keto Diet
Nutritional ketosis has shown promise as a therapeutic treatment for epilepsy and can be a helpful tool for managing blood sugar levels in individuals with type 2 diabetes or for those seeking weight loss.
Components of a Keto Diet
A typical keto diet consists of:
- A moderate amount of protein.
- A high amount of fats, including full-fat dairy, cheese, oils, fatty meats and fish, avocado, nuts, and seeds.
- A limited amount of non-starchy vegetables and low-glycemic foods.
The macronutrient distribution typically falls around 75% to 90% of calories from fat, 12% to 15% from protein, and 5% to 10% from carbohydrates.
The exact carbohydrate limit required to achieve ketosis varies from person to person, but it is generally around 50 grams or less per day.
Potential Risks and Drawbacks of the Keto Diet
Despite its potential benefits, the keto diet also carries several risks and drawbacks:
High Cholesterol
Elevated cholesterol levels are a common concern associated with the keto diet. While some individuals may experience improved lipid panels due to reduced consumption of processed foods, many others see a significant increase in cholesterol and triglyceride levels, primarily due to the high intake of saturated fat. This is especially true when the keto diet is followed in an unhealthy manner, with a lack of vegetables and an overreliance on bacon, cheese, and cream.
Social Limitations
The restrictive nature of the keto diet can make it challenging to socialize and dine out with friends. While keto-friendly options are becoming more readily available, adhering to the diet long-term can be difficult and unsustainable.
Weight Regain
A common disadvantage of the keto diet is that weight loss is often regained quickly once the diet is discontinued. Furthermore, individuals may find themselves in a worse position than before, with elevated cholesterol levels in addition to the regained weight.
Constipation
The keto diet can lead to constipation due to insufficient fiber intake, which can also increase the risk of colon cancer.
Nutrient Deficiencies
Restricting carbohydrates can lead to deficiencies in essential nutrients found in whole grains and fruits, such as B vitamins and magnesium.
Weighing the Evidence: Which Diet is Right for You?
Determining the "best" diet ultimately depends on individual needs, preferences, and health goals. While both the keto diet and plant-based diets can lead to weight loss, their long-term sustainability and overall health impacts differ significantly.
Long-Term Studies
After a year or so, studies show that the changes in weight loss arenât statistically significant.
A Balanced Approach
A balanced approach, emphasizing a variety of nutrient-dense foods, including plenty of vegetables, lean protein, and whole grains, is generally recommended for long-term health and well-being.
Before making any significant dietary changes, it is essential to consult with a healthcare professional, especially if you have any underlying health conditions such as cardiovascular disease, hypertension, diabetes, or chronic kidney disease. Even if you are healthy, seeking guidance from a healthcare provider can help you establish baseline health markers and monitor any changes that may occur as a result of dietary modifications.
Ultimately, the most successful diet is the one that you can consistently adhere to and that supports your overall health and well-being.
The Role of Nutrition in Cancer Prevention and Treatment
As the incidence of cancer and metabolic disorders continues to rise, the importance of nutrition in both prevention and treatment has become increasingly apparent. Dietary intake can influence various pathways involved in carcinogenesis and tumor progression.
Plant-Enriched Diets and Cancer Risk
Consumption of a plant-enriched diet has been associated with a reduced risk of cancer, aligning with dietary guidelines for cancer prevention.
WFPBD vs. KD: Contrasting Approaches
Both whole foods plant-based diets (WFPBD) and ketogenic diets (KD) have been explored for their potential anticancer effects, despite their stark differences in nutrient composition. WFPBDs are associated with increased fiber, phytochemicals, and butyrate levels, while KDs may exert anticancer effects by increasing β-hydroxybutyrate levels.
WFPBD: Maximizing Nutrient Density
The WFPBD emphasizes nutrient-dense plant foods while minimizing processed foods, oils, and animal products. It is a minimally processed, low-fat, moderate-to-high carbohydrate diet that prioritizes micronutrient density.
KD: Reversing the Macronutrient Profile
The KD challenges conventional dietary wisdom by reversing the macronutrient profile, prioritizing fat and protein over carbohydrates. It aims to promote the production of ketone bodies from fatty acids through a very low carbohydrate, high fat, and moderate protein intake.
Epidemiological Evidence
Epidemiological studies have consistently shown that plant-based diets are associated with a reduced cancer incidence. Conversely, long-term epidemiological evidence for the KD is lacking, and studies have indicated that diets low in plant foods may increase cancer risk.
The American Institute for Cancer Research/World Cancer Research Fund and the American Cancer Society
These organizations recommend a diet comprising primarily whole plant-based foods and limited sugary drinks, highly processed foods, refined grains, and red and processed meats based on cumulative generalizable evidence for cancer.
Common Mechanisms
Despite their differences, both the KD and WFPBD may share some common mechanisms by which they can potentially decrease cancer risk.
Insulin and the PI3K Signaling Cascade
High insulin levels can promote and sustain tumor growth, as insulin activates the phosphoinositide 3-kinase (PI3K) signaling cascade, which regulates cellular metabolism, survival, and proliferation. WFPBDs are associated with decreased fasting plasma insulin concentrations and improved insulin sensitivity, while KD clinical trials have also reported decreased insulin levels, although some preclinical studies have shown increased insulin resistance.
Fiber and the Gut Microbiome
Fiber intake has been linked to positive effects in the setting of colon cancer prevention. Studies have shown that dietary fiber intake can influence the gut microbiome and impact the response to cancer treatments.
Phytochemicals and Short-Chain Fatty Acids (SCFAs)
Plant foods contain phytochemicals, such as flavonoids, that have anticancer properties. Both diets can increase short-chain fatty acids (SCFAs), although through different mechanisms.
β-Hydroxybutyrate (βHB)
KDs are associated with increased blood ketone body levels, mainly β-hydroxybutyrate (βHB), a SCFA. While βHB has HDAC inhibitory effects, its anticancer effects are debated, with conflicting evidence suggesting both anticancer and pro-inflammatory/tumor proliferative effects.
Clinical Trials and Dietary Interventions
While most completed interventional studies have focused on increasing fruit and vegetable intake or reducing fat intake, several trials have tested plant-enriched diets in breast cancer patients.
The Womenâs Health Initiative (WHI) Study
This study compared the effect of a reduced fat dietary intervention with a usual diet group in postmenopausal women and showed that those in the low-fat group had improved breast cancerâspecific and overall survival.
The Womenâs Healthy Eating and Living (WHEL) Study and the Womenâs Intervention Nutrition Study (WINS)
These studies tested the effects of dietary interventions on breast cancer outcomes, with varying results.
Systematic Reviews and Meta-Analyses
Systematic reviews and meta-analyses evaluating the efficacy of KD as antitumor therapy have concluded that there is inconclusive evidence.
Ongoing Trials
Despite the epidemiologic evidence supporting plant-enriched diets, there are currently more ongoing trials testing KDs than WFPBDs in cancer populations.
Challenges in Nutrition Studies
Nutrition trials in oncology face several challenges, including differences in intervention duration, lack of standardization of macronutrient content, conflation of weight loss effect vs nutrient intake effect, and suboptimal adherence.
Plant-Based KDs
Plant-based KDs are a potential alternative, offering benefits from both dietary patterns, although they may be difficult to sustain due to the limited number of high-fat plant foods.
Recommendations
The preponderance of available data supports plant-enriched diets for cancer prevention and control, although confirmatory prospective trials are required. WFPBDs are part of established, universally recommended healthy lifestyle habits.