The New England Journal of MedicineDiets

Exploring the Nutritional Paradigms: Insights into the Composition, Health Effects, and Practical Implications of Common Diets

This article reviews the constituents, health effects, and underlying mechanisms of widely recognized and scientifically explored diets. It highlights the Mediterranean, vegetarian, low-fat, carbohydrate-restricted, low-glycemic-index, Paleolithic, DASH, MIND, and time-restricted diets, providing insights into their potential health outcomes and practical applications in clinical settings. The focus is on dietary patterns and their impact on health, independent of body weight, emphasizing the importance of understanding these diets’ mechanisms and efficacy for patient care.

Key Points:

Mediterranean Diet

• Origin: Post-World War II research by Leland Allbaugh and Ancel Keys.
• Composition: Predominantly plant foods, moderate dairy, low red meat, wine with meals.
• Health Benefits: Reduced risk of death from any cause, cardiovascular diseases, cancer, neurodegenerative diseases, and diabetes.
• Mechanisms: Reductions in blood lipids, inflammatory and oxidative stress markers, improved insulin sensitivity, enhanced endothelial and antithrombotic function.

Vegetarian Diets

• Types: Vegan, lacto-vegetarian, ovo-vegetarian, lacto-ovo-vegetarian, pescatarian, flexitarian.
• Health Benefits: Reduced risk of cardiovascular diseases, ischemic heart disease, dyslipidemia, diabetes, certain cancers.
• Challenges: Potential nutrient deficiencies, especially vitamin B12 in vegans.
• Mitigation: Nutritional supplementation or intermittent consumption of animal protein.

Low-Fat Diets

• Definition: Lipids <30% of total energy intake; very-low-fat diets <15%.
• Examples: Ornish diet.
• Health Benefits: Weight loss, reduced risk of breast cancer, beneficial effects on blood lipids and blood pressure, reduced risk of myocardial infarction, diabetes, and death from any cause.
• Considerations: Nutrient adequacy dependent on food choices, potential challenges in adherence.

Carbohydrate-Restricted Diets

• Examples: Atkins, ketogenic, and low-carbohydrate diets.
• Health Benefits: Weight loss, improved cardiovascular risk factors, reduced frequency of seizures in drug-resistant epilepsy.
• Mechanisms: Metabolic changes similar to starvation state, effects on plasma levels of free fatty acids, insulin, glucose, and ketone bodies.
• Challenges: Adherence variability, potential adverse effects like gastrointestinal symptoms and dyslipidemia.

Low-Glycemic-Index Diet

• Definition: Focus on foods that induce low glycemic responses.
• Health Benefits: Management of diabetes and related cardiometabolic conditions.

Paleolithic Diet

• Composition: Uncultivated plants, wild game, fish, minimal processed foods.
• Health Benefits: Improvements in insulin resistance, dyslipidemia, hypertension, inflammation, body composition, and weight-related measures.

DASH Diet

• Origin: Dietary Approaches to Stop Hypertension (DASH) trial.
• Composition: Rich in fruits, vegetables, low-fat dairy, low saturated fats.
• Health Benefits: Reduced blood pressure, decreased incidence of cardiovascular disease, metabolic diseases, and all-cause mortality.
• Variations: DASH-sodium, OmniHeart diet.

MIND Diet

• Composition: Combination of Mediterranean and DASH diets with emphasis on berries and green leafy vegetables.
• Health Benefits: Potential cognitive benefits, under investigation in clinical trials.

Time-Restricted Diets

• Types: Intermittent fasting, alternate-day fasting, time-restricted eating.
• Health Benefits: Improvements in energy metabolism, cardiovascular health, potential effects on cancer and neurodegenerative processes.
• Mechanisms: Metabolic switch from glucose to fatty acids and ketone bodies, increased resistance to stress.

A Lancet study suggests a 15-30% decrease in all-cause and cardiovascular related mortality when comparing people who eat the highest amount of fiber to those who eat the least. Eating fiber-rich foods also reduced incidence of coronary heart disease, stroke, type 2 diabetes and colorectal cancer by 16-24%.

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