MN02 - Common & Popular Diets

Why is the Mediterranean diet often called the “gold standard” diet?

Because it has strong, consistent scientific evidence supporting benefits for longevity, cardiovascular health, cognition, and overall disease risk reduction.

What makes the Mediterranean diet a “dietary pattern” rather than a strict diet?

It is a flexible pattern emphasizing food groups and habits rather than strict macronutrient rules.

What protein sources are emphasized in the Mediterranean diet?

Fish and poultry are emphasized, while red meat is minimized.

What is the significance of fish consumption in the Mediterranean diet?

It increases omega-3 fatty acid intake, improving the omega-6:omega-3 ratio.

Why is the omega-6 to omega-3 ratio important?

A lower ratio is associated with reduced inflammation and improved cardiovascular outcomes.

What type of carbohydrates are emphasized in the Mediterranean diet?

Low glycemic index carbohydrates.

Why are low glycemic index carbohydrates beneficial?

They prevent rapid spikes in blood glucose and insulin.

What micronutrients are abundant in the Mediterranean diet?

Antioxidants and polyphenols.

What is the role of polyphenols in health?

They reduce oxidative stress and inflammation.

Why is fiber intake high in the Mediterranean diet?

Due to high intake of fruits, vegetables, legumes, and whole grains.

What are the major health outcomes associated with the Mediterranean diet?

• Increased longevity

• Preserved cognition

• Reduced cardiovascular disease risk

• Some evidence for reduced cancer risk

What does meta-analysis data show about the Mediterranean diet vs low-fat diets?

It may outperform low-fat diets in improving health outcomes.

What are the main categories of vegetarian diets from least to most restrictive?

Flexitarian → Lacto-ovo → Lacto → Vegan → Fruitarian

What defines a lacto-ovo vegetarian?

Consumes dairy and eggs but no meat.

What defines a lacto vegetarian?

Consumes dairy but no eggs or meat.

What defines a vegan?

Consumes no animal products whatsoever.

What are the macronutrient characteristics of a well-constructed vegetarian diet?

• Low fat overall

• Low saturated fat

• Low trans fat

• Low cholesterol

• ~20% of calories from fat

• High fiber

• High antioxidants

Why is it difficult to compare vegetarian vs non-vegetarian health outcomes?

Vegetarians often differ in lifestyle factors such as exercise, smoking, and alcohol use.

What cardiovascular benefits are associated with vegetarian diets?

Reduced coronary heart disease and arterial disease.

What metabolic benefits are associated with vegetarian diets?

• Lower body weight

• Healthier blood pressure

How does dietary restriction level impact nutritional risk?

More restrictive diets increase risk of deficiencies.

Why are processed vegetarian foods potentially unhealthy?

They may contain high levels of salt, sugar, and fat.

Why must fiber intake increases be managed carefully?

Increased fiber intake requires increased water consumption to prevent GI issues.

Why is protein a concern primarily for strict vegans?

Plant proteins may have limiting amino acids and lower digestibility.

What are common plant protein sources?

Beans, legumes, nuts, seeds, tofu, soy, meat substitutes.

Which amino acids are limited in legumes?

Methionine and tryptophan.

Which amino acids are limited in grains?

Lysine and isoleucine.

What is protein complementation?

Combining plant foods to obtain all essential amino acids.

Is protein complementation required at every meal?

No, because the body maintains amino acid pools.

What are digestibility percentages for protein sources?

• Animal: ~90%

• Legumes: 80–90%

• Other plants: 70–90%

How does cooking affect protein digestibility?

Moist heat increases digestibility; dry heat reduces it.

What is PDCAAS (Protein Digestibility-Corrected Amino Acid Score)?

A measure of protein quality based on amino acid composition and digestibility.

Why is B12 deficiency only a risk in true vegans?

Because B12 is only naturally found in animal-derived foods.

Where does B12 originate?

From microbial synthesis.

How long are B12 stores sufficient?

~4 years.

Why is B12 deficiency dangerous?

Neurological damage can be irreversible.

What are ALL symptoms of B12 deficiency?

• Anemia

• Fatigue

• Constipation

• Anorexia

• Numbness/tingling

• Depression

• Confusion

• Poor memory

• Mouth/tongue sores

How can vegans prevent B12 deficiency?

Fortified foods or supplements.

Which micronutrients are concerns in vegetarian diets?

Iron, zinc, calcium, vitamin D.

Why is iron bioavailability lower in plant foods?

Plant iron (non-heme) is less absorbable.

How can iron intake be improved?

Use varied sources and cook with cast iron.

How can vitamin D be obtained without dairy?

Sun exposure (~20 min) or supplements.

What is the primary purpose of the DASH diet?

To reduce blood pressure (hypertension).

What foods are emphasized in DASH?

Fruits, vegetables, whole grains, low-fat dairy, fish, poultry, beans, nuts, vegetable oils.

What foods are limited in DASH?

Saturated fat, fatty meats, full-fat dairy, tropical oils, sweets, sugar-sweetened beverages.

What nutrients are increased in DASH?

Potassium, calcium, magnesium, fiber, protein.

What nutrients are reduced?

Sodium, saturated fat, cholesterol.

What is the DASH sodium target?

<1500 mg/day (~¾ teaspoon salt).

What BP reduction occurs with sodium reduction alone?

• Systolic: −2.1 to −4.6 mmHg

• Diastolic: −1.1 to −2.4 mmHg

What BP reduction occurs with DASH + low sodium?

• Systolic: −8.9 mmHg

• Diastolic: −4.5 mmHg

Why is DASH more effective than sodium reduction alone?

Because multiple dietary factors improve blood pressure, not just sodium reduction.

What percentage of people are salt-sensitive?

~26%.

What does this imply for treatment?

Sodium restriction alone will not work for all individuals.

Why is potassium important?

It lowers blood pressure and counteracts sodium.

What dietary issue exists with potassium intake?

Most Americans consume less than recommended.

Do specialty salts provide health benefits?

No evidence supports benefits.

What is a key concern with specialty salts?

They are often not iodized.

What % of calories should come from carbohydrates?

~45–65%.

What is the RDA for carbohydrates?

130 g/day.

What are the three definitions of low-carb diets?

1. <45% calories

2. <130g/day

3. <50g/day (ketogenic)

What is nutritional ketosis?

A metabolic state where ketones are used as fuel (1–5 mmol/L).

What is diabetic ketoacidosis?

A life-threatening condition with high ketones (15–30 mmol/L), high glucose, and low pH.

Can a healthy person develop ketoacidosis on a ketogenic diet?

No, due to normal insulin regulation.

What benefits of the keto diet are supported by evidence?

• Weight loss

• Improved glucose control

• Improved lipid profile

• Reduced seizures

What is intermittent fasting?

Voluntary restriction of food intake for periods of time.

What are the 4 IF categories?

• Intermittent fasting

• Periodic fasting

• Time-restricted feeding

• Religious fasting

What metabolic changes occur during fasting?

• Glycogen depletion

• Fat mobilization

• Ketone production

• Reduced leptin (reduced leptin → increased hunger)

Why is IF hard to evaluate?

Effects overlap with calorie restriction.

What are detox diets?

Diets claiming to eliminate toxins and improve health.

What evidence supports detox diets?

None—no rigorous clinical trials.

Which organs detoxify the body?

Liver, kidneys, skin, bladder.

What are risks of detox diets?

• Dehydration

• Electrolyte imbalance

• Mineral loss

• Kidney stone risk

• Diarrhea

• Malabsorption