Nutrition Lecture 2 (Therapeutic Diets)

What were the top causes of death in 2021?

heart disease, cancer, COVID-19, unintentional injuries, stroke

What is the leading driver of premature death?

cardiometabolic disease

What is a modifiable risk factor influencing multiple top killers?

diet

What fuels confusion?

conflicting headlines & new studies

What are the three broad categories of foods?

1) healthful foods (strong consensus)

2) debatable foods (mixed evidence)

3) harmful foods

What are examples of healthful foods?

fruits, vegetables, nuts, whole grains, PUFAs, omega-3s

What are examples of debatable foods?

dairy, eggs, fish

What are examples of harmful foods?

added sugar, refined grains, processed meats

What is the clinical priority?

shift intake toward "green box" healthful foods

Diet

The foods and beverages a person habitually consumes.

Dietary pattern

The overall combination, quantity, variety, and frequency of foods and beverages consumed over time.

Healthy diet

A dietary pattern that provides adequate nutrients and energy while supporting health, reducing disease risk, and limiting components associated with adverse health outcomes.

Nutrition

The process by which the body obtains, uses, and metabolizes nutrients from food to support growth, maintenance, repair, and normal physiological function.

Dietary intake

The actual amount and types of foods, beverages, nutrients, or other dietary components consumed by an individual during a specified period.

Processed foods

Foods altered during preparation; packaged with additives, preservatives, and flavoring

Ultra-processed

industrial formulations high in refined starches, added sugars, oils, sodium

Refined grains

bran and germ removed → less fiber, nutrients (e.g., white flour, white rice)

Added sugars

syrups and caloric sweeteners added during processing/prep (e.g., soda, desserts)

Red meat

beef, pork, lamb

Processed meat

cured, smoked, salted, chemical preservatives

Why are foods processed?

- affordability (efficient and inexpensive)

- accessibility

- food safety (pasteurization)

- food preservation (extends shelf life)

- improves food tolerance (lactose and gluten)

- enrichment

- fortification

What is fortification?

Adding micronutrients to improve the nutritional quality and improve public health -> Iron in infant cereal, Milk is fortified with vitamins A and D and Salt!

What are the adverse effects of food processing?

- additives that would not be used in home cooking

- food coloring -> hyperactivity & thyroid tumor

- sodium nitrate (high in cured meats) -> cancer

- artificial sweeteners -> headache & GI side effects

- SUGAR (added to increase tolerability)

What is the global perspective of the EAT-Lance summary report?

healthy diets within planetary boundaries

What does the EAT-Lance summary report emphasize?

vegetables, druits, whole grains, legumes, nuts, unsaturated oils

What foods are limited in the EAT-Lance summary report?

red/processed meat, refined grains, added sugars, high dairy

What is the goal of the EAT-Lance summary report?

↓ global mortality, ↓ environmental impact

What is a plant-based diet?

eating pattern emphasizing whole plant foods (vegetables, fruits, legumes, nuts, seeds, whole grains)

Mechanism of plant-based diet: fiber

binds bile acids (↓ LDL), slows glucose absorption, ↑ satiety

Mechanism of plant-based diet: phytochemicals & antioxidants

↓ oxidative stress, regulate gene expression

Mechanism of plant-based diet: gut microbiome

fermentation → SCFA (butyrate, acetate) → improved insulin sensitivity, ↓ inflammation

Mechanism of plant-based diet: lower TMAO (vs. meat-based diets)

↓ CVD risk

What do plant-predominant dietary patterns emphasize?

- Vegetables and fruits

- Whole grains

- Legumes: beans, peas, lentils

- Nuts and seeds

- Unsaturated plant oils

- Minimally processed plant foods

What may be included in varying amounts in plant-based diets?

- Fish/seafood

- Dairy

- Eggs

- Poultry

- Meat

Examples of plant-based diets.

Mediterranean, DASH, Portfolio, MIND, flexitarian, pescatarian, vegetarian, vegan, whole-food plant-based

Vegetarian

excludes meat/poultry; may include dairy and/or eggs

Vegan

excludes all animal-derived foods (NO meat, dairy, eggs, poultry, fish)

Whole-food plant-based (WFPB)

emphasizes minimally processed plant foods and generally minimizes or excludes animal foods and highly processed foods

Flexitarian

predominantly plant-based but periodically includes meat/animal foods

Pescatarian

excludes meat/poultry but includes fish/seafood

Lacto-vegetarian

includes dairy

Ovo-vegetarian

includes eggs

Lacto-ovo vegetarian

includes both dairy & eggs

What do vegetarian diets emphasize?

vegetables, fruits, legumes, grains, nuts, seeds

CVD benefits of a vegetarian diet

↓ LDL, ↓ blood pressure, ↓ ischemic heart disease risk

Diabetes benefits of a vegetarian diet

↓ incidence, improved glycemic control

Cancer benefits of a vegetarian diet

modest ↓ in some cancers (esp. GI)

Obesity benefits of a vegetarian diet

generally lower BMI vs. omnivores

Mortality benefits of a vegetarian diet

↓ all-cause mortality in large cohorts (Adventist Health Studies, EPIC)

What nutrients should be monitored in a vegetarian diet?

- iron (non-heme form less bioavailable; pair with vitamin C)

- vitamin B12 (may be low if dairy/eggs limited)

- zinc, iodine, calcium, omega 3s (ALA → EPA/DHA) (ensure adequate plant sources)

* With careful planning, meets all nutrient needs*

Additional concerns with vegetarian diets

- Disordered eating

- GI Symptoms

- Fatigue or low energy

- Soy (endocrine disruption)

What do vegan diets sometimes exclude?

honey and other animal-based fillers in food

What are lifestyle choices vegans may make?

no leather/fur, beauty products

What does a vegan diet include?

cereals, fruits, vegetables, legumes, and nuts

*be aware of carbo-vegans*

What vitamin MUST be supplemented in vegan diets?

vitamin B12

Other nutritional concerns in vegan diets

- iron (non-heme form less bioavailable; pair with vitamin C)

- calcium, iodine, zinc, omega-3s (EPA/DHA)

- protein quality (ensure variety; legumes, soy, quinoa, seitan)

What are ultra-processed vegan foods (mock meats, packaged snacks) often high and low in?

high sodium; low nutrients

Additional concerns with vegan diets

- Bone mineral density (lower peak BMD but also slower bone loss)

- Digestive upset

- Fatigue

- Soy

- Neurotransmitter Imbalances

- Orthorexia

What is the Mediterranean diet?

Traditional diet from countries bordering the Mediterranean Sea

Core components of the Mediterranean diet?

- High: vegetables, fruits, legumes, nuts, seeds, whole grains

- Olive oil as the predominant added fat

- Regular fish/seafood

- Low-to-moderate dairy, eggs, poultry

- Limited red and processed meats

- Limited refined carbohydrates and highly processed foods

What is the benefit of the Mediterranean diet?

cardiovascular risk reduction

What is the Mediterranean diet associated with?

improved cardiometabolic outcomes

When might the Mediterranean diet be a first-line dietary pattern?

patients with cardiovascular or metabolic risk

*widely used in research and clinical guidelines*

Benefit of the Mediterranean diet: Healthy fats (olive oil (MUFA), nuts/seeds (PUFA), fish (omega-3s))

↓ inflammation, improve lipids

Benefit of the Mediterranean diet: Fiber & plant compounds

lower LDL, ↑ endothelial function, ↓ oxidative stress

Benefit of the Mediterranean diet: Gut microbiome modulation (plant diversity)

↑ SCFA, ↓ TMAO

Benefit of the Mediterranean diet: Moderate wine (polyphenols)

potential ↑ HDL, ↓ clotting (but not required)

What is TMAO (trimethylamine-N-oxide)?

- metabolite from red meat, egg yolk, and some seafood via gut bacteria

- gut-derived metabolite from carnitine & choline (red meat, egg yolk, some seafood)

What is the mechanism of TMAO?

produced by gut bacteria → liver → systemic circulation

What is TMAO linked to?

- ↑ platelet reactivity

- ↑ atherosclerosis progression

- ↑ CV events in observational studies

Regarding TMAO, what is an emerging therapeutic target?

dietary modulation of the microbiome

What chronic disease does a Mediterranean prescription have the strongest evidence of benefiting?

cardiovascular disease

What is a Mediterranean prescription associated with?

- ↓ Major cardiovascular events

- ↓ Stroke risk

- Improved BP

- Improved glycemic control

- Improved overall dietary quality

What are the potential applications of a Mediterranean prescription?

- Primary CVD prevention

- Secondary CVD prevention

- Hypertension

- Type 2 diabetes/metabolic syndrome

- Dyslipidemia

Patient counseling PEARLS for the Mediterranean diet.

- Center plate around vegetables & legumes

- Use olive oil as primary fat

- Swap red/processed meat → fish or beans

- Include nuts/seeds daily (handful)

- Encourage whole grains over refined

- Adapt to culture (Mediterranean = a pattern, not a cuisine)

What is a Mediterranean diet high in?

- Polyphenols and flavonoids (i.e. Resveratrol)

- Fiber

- Monounsaturated fats (olive oil, avocado, nuts/seeds)

- Polyunsaturated fats (nuts/seeds, fish)

- Potassium

- Magnesium

- B12, iron, amino acids

What is a Mediterranean diet low in?

- Salt

- Processed foods

- Trans-fat and HFCS

- Saturated fats

- Calcium

*Price tag $$$*

What is a Portfolio diet specifically designed for?

LDL-C reduction

What does a Portfolio diet combine?

Several cholesterol-lowering dietary components:

- Plant sterols

- Viscous/soluble fiber

- Nuts

- Soy/other plant proteins

- Low saturated-fat dietary pattern

What is the clinical use of the Portfolio diet?

hypercholesterolemia

What does the MIND dietary pattern stand for?

Mediterranean-DASH Intervention for Neurodegenerative Delay

What does the MIND dietary pattern combine?

Mediterranean & DASH principles

What does the MIND dietary pattern place emphasis on?

- Leafy green vegetables

- Other vegetables

- Berries

- Nuts

- Whole grains

- Beans

- Fish

- Poultry

- Olive oil

What does the MIND dietary pattern limit?

- Red meat

- Butter/margarine

- Cheese

- Pastries/sweets

- Fried/fast foods

What is the proposed clinical target of the MIND dietary pattern?

cognitive health/healthy aging

Describe the current evidence behind the MIND dietary pattern.

Observational evidence has associated greater MIND adherence with less cognitive decline, but the major 3-year RCT found no statistically significant difference in cognition or brain MRI outcomes between the MIND intervention and control group.

What was the Lyon Heart Study?

Landmark secondary-prevention trial in patients with previous myocardial infarction

What were the patients in the Lyon Heart Study randomized to?

- Mediterranean-type dietary intervention

- Control/prudent Western dietary pattern

*Follow-up ultimately averaged approximately 46 months*

What question did the Lyon Heart Study aim to answer?

Can a Mediterranean-type dietary pattern reduce recurrent cardiovascular events after MI?

What did the Lyon Heart Study intervention emphasize?

- More fruits and vegetables

- More bread/cereals and legumes

- Fish

- Less red/processed meat

- Replacement of butter/cream with a study-provided canola-oil margarine

- Higher oleic acid and α-linolenic acid intake

What were the results of the Lyon Heart Study at extended follow-up?

Cardiac death + nonfatal MI

- Mediterranean group: 14 events

- Control group: 44 events

Broader cardiovascular endpoint:

- Mediterranean group: 27 events

- Control group: 90 events

Statistics/conclusions of the Lyon Heart Study.

- Adjusted relative risks across cardiovascular endpoints were approximately 0.28-0.53.

- The protective association persisted for approximately 4 years following the initial MI.

What does DASH stand for?

Dietary Approaches to Stop Hypertension

What was the DASH diet originally developed as?

A dietary pattern to lower blood pressure, but now used more broadly for cardiometabolic risk reduction.

What is a DASH diet high in?

- Vegetables

- Fruits

- Whole grains

- Legumes

- Nuts and seeds

- Low-fat or fat-free dairy

- Fish and poultry

What is a DASH diet low in?

- Sodium

- Saturated fat

- Red and processed meats

- Full-fat dairy

- Sugar-sweetened beverages

- Sweets and highly processed foods

True or False: DASH is NOT just a low-sodium diet.

True

What is the effect of a DASH diet across randomized trials?

consistently lowered BP

SBP ↓ ~3.2 mm Hg

DBP ↓ ~2.5 mm Hg

Notes about BP reduction on the DASH diet

- BP reduction occurred across participants with differing baseline BP status

- Greater SBP reduction was observed in studies with higher baseline sodium intake

- Effects vary with baseline BP, sodium intake, population, and study design

Clinical significance of the DASH diet

Even modest population-level reductions in SBP are associated with meaningful reductions in cardiovascular risk.