Skip & Fuel's Take
Real people need real nutrition, not expensive supplements that don't work. During my 17kg transformation, I learned which nutrients actually matter for sustainable weight loss. This guide cuts through the supplement industry BS and focuses on what works.
Skip & Fuel Hack: Vitamin A from real food sources like liver and sweet potatoes was a game-changer during my 36-hour fasts. It kept my immune system strong and my energy stable when I needed it most.
Vitamin A: Food Sources and Bioavailability
Vitamin A isn't just about carrots and good eyesight—it's a powerhouse nutrient that affects everything from your immune system to your skin health. But here's the thing: not all vitamin A is created equal, and how you eat it matters just as much as what you eat.
During my 36-hour weekend fasts, I learned that getting vitamin A right was crucial for maintaining energy and keeping my immune system strong. The key? Understanding which foods give you the most bang for your buck and how to maximize absorption.
Preformed Vitamin A Sources
Animal Products
Liver and Organ Meats
- Beef liver: 6,582 μg RAE per 100g (2,200% DV)
- Chicken liver: 3,333 μg RAE per 100g (1,111% DV)
- Pork liver: 2,500 μg RAE per 100g (833% DV)
- Lamb liver: 7,500 μg RAE per 100g (2,500% DV)
- Cod liver oil: 30,000 μg RAE per 100g (10,000% DV)
Dairy Products
- Butter: 684 μg RAE per 100g (228% DV)
- Cheddar cheese: 330 μg RAE per 100g (110% DV)
- Whole milk: 46 μg RAE per 100g (15% DV)
- Yogurt: 27 μg RAE per 100g (9% DV)
- Cream: 1,000 μg RAE per 100g (333% DV)
Fish and Seafood
- Salmon: 12 μg RAE per 100g (4% DV)
- Tuna: 655 μg RAE per 100g (218% DV)
- Mackerel: 54 μg RAE per 100g (18% DV)
- Sardines: 32 μg RAE per 100g (11% DV)
- Shrimp: 54 μg RAE per 100g (18% DV)
Eggs
- Whole egg: 140 μg RAE per 100g (47% DV)
- Egg yolk: 381 μg RAE per 100g (127% DV)
- Egg white: 0 μg RAE per 100g (0% DV)
- Duck egg: 194 μg RAE per 100g (65% DV)
- Quail egg: 156 μg RAE per 100g (52% DV)
Fortified Foods
Fortified Milk
- Fortified whole milk: 150 μg RAE per 100g (50% DV)
- Fortified skim milk: 150 μg RAE per 100g (50% DV)
- Fortified plant milk: 150 μg RAE per 100g (50% DV)
- Fortified yogurt: 150 μg RAE per 100g (50% DV)
Fortified Cereals
- Fortified breakfast cereals: 150-300 μg RAE per serving
- Fortified rice: 150 μg RAE per 100g (50% DV)
- Fortified pasta: 150 μg RAE per 100g (50% DV)
- Fortified bread: 150 μg RAE per 100g (50% DV)
Fortified Margarine
- Fortified margarine: 450 μg RAE per 100g (150% DV)
- Fortified spreads: 300-600 μg RAE per 100g
- Fortified cooking oils: 150-300 μg RAE per 100g
Provitamin A Carotenoid Sources
Orange and Yellow Vegetables
Carrots
- Raw carrots: 835 μg RAE per 100g (278% DV)
- Cooked carrots: 852 μg RAE per 100g (284% DV)
- Carrot juice: 956 μg RAE per 100g (319% DV)
- Baby carrots: 828 μg RAE per 100g (276% DV)
- Purple carrots: 1,000 μg RAE per 100g (333% DV)
Sweet Potatoes
- Raw sweet potato: 709 μg RAE per 100g (236% DV)
- Baked sweet potato: 1,043 μg RAE per 100g (348% DV)
- Sweet potato fries: 1,043 μg RAE per 100g (348% DV)
- Purple sweet potato: 1,043 μg RAE per 100g (348% DV)
- Sweet potato leaves: 377 μg RAE per 100g (126% DV)
Pumpkins
- Raw pumpkin: 426 μg RAE per 100g (142% DV)
- Cooked pumpkin: 558 μg RAE per 100g (186% DV)
- Pumpkin puree: 558 μg RAE per 100g (186% DV)
- Pumpkin seeds: 1 μg RAE per 100g (0.3% DV)
- Pumpkin leaves: 194 μg RAE per 100g (65% DV)
Winter Squash
- Butternut squash: 532 μg RAE per 100g (177% DV)
- Acorn squash: 367 μg RAE per 100g (122% DV)
- Spaghetti squash: 26 μg RAE per 100g (9% DV)
- Kabocha squash: 1,043 μg RAE per 100g (348% DV)
- Delicata squash: 367 μg RAE per 100g (122% DV)
Dark Green Leafy Vegetables
Spinach
- Raw spinach: 469 μg RAE per 100g (156% DV)
- Cooked spinach: 524 μg RAE per 100g (175% DV)
- Frozen spinach: 524 μg RAE per 100g (175% DV)
- Baby spinach: 469 μg RAE per 100g (156% DV)
- Spinach powder: 5,000 μg RAE per 100g (1,667% DV)
Kale
- Raw kale: 241 μg RAE per 100g (80% DV)
- Cooked kale: 681 μg RAE per 100g (227% DV)
- Kale chips: 241 μg RAE per 100g (80% DV)
- Baby kale: 241 μg RAE per 100g (80% DV)
- Kale powder: 2,000 μg RAE per 100g (667% DV)
Collard Greens
- Raw collard greens: 333 μg RAE per 100g (111% DV)
- Cooked collard greens: 380 μg RAE per 100g (127% DV)
- Frozen collard greens: 380 μg RAE per 100g (127% DV)
- Collard green wraps: 333 μg RAE per 100g (111% DV)
Swiss Chard
- Raw Swiss chard: 306 μg RAE per 100g (102% DV)
- Cooked Swiss chard: 306 μg RAE per 100g (102% DV)
- Rainbow chard: 306 μg RAE per 100g (102% DV)
- Chard stems: 153 μg RAE per 100g (51% DV)
Orange and Yellow Fruits
Mangoes
- Raw mango: 54 μg RAE per 100g (18% DV)
- Dried mango: 108 μg RAE per 100g (36% DV)
- Mango juice: 54 μg RAE per 100g (18% DV)
- Frozen mango: 54 μg RAE per 100g (18% DV)
- Mango puree: 54 μg RAE per 100g (18% DV)
Cantaloupe
- Raw cantaloupe: 169 μg RAE per 100g (56% DV)
- Cantaloupe juice: 169 μg RAE per 100g (56% DV)
- Frozen cantaloupe: 169 μg RAE per 100g (56% DV)
- Cantaloupe balls: 169 μg RAE per 100g (56% DV)
Apricots
- Raw apricots: 96 μg RAE per 100g (32% DV)
- Dried apricots: 180 μg RAE per 100g (60% DV)
- Apricot juice: 96 μg RAE per 100g (32% DV)
- Frozen apricots: 96 μg RAE per 100g (32% DV)
Papaya
- Raw papaya: 47 μg RAE per 100g (16% DV)
- Papaya juice: 47 μg RAE per 100g (16% DV)
- Frozen papaya: 47 μg RAE per 100g (16% DV)
- Papaya seeds: 0 μg RAE per 100g (0% DV)
Other Provitamin A Sources
Red Bell Peppers
- Raw red bell pepper: 157 μg RAE per 100g (52% DV)
- Cooked red bell pepper: 157 μg RAE per 100g (52% DV)
- Roasted red bell pepper: 157 μg RAE per 100g (52% DV)
- Red bell pepper powder: 1,000 μg RAE per 100g (333% DV)
Tomatoes
- Raw tomatoes: 42 μg RAE per 100g (14% DV)
- Cooked tomatoes: 42 μg RAE per 100g (14% DV)
- Tomato paste: 42 μg RAE per 100g (14% DV)
- Sun-dried tomatoes: 42 μg RAE per 100g (14% DV)
Peaches
- Raw peaches: 16 μg RAE per 100g (5% DV)
- Dried peaches: 32 μg RAE per 100g (11% DV)
- Peach juice: 16 μg RAE per 100g (5% DV)
- Frozen peaches: 16 μg RAE per 100g (5% DV)
Bioavailability Factors
Food Matrix Effects
Raw vs. Cooked
- Raw vegetables: Lower bioavailability (5-10%)
- Cooked vegetables: Higher bioavailability (15-30%)
- Steaming: Optimal cooking method
- Boiling: Some nutrient loss to water
- Roasting: Good bioavailability, enhanced flavor
Processing Methods
- Juicing: High bioavailability, rapid absorption
- Pureeing: Increased surface area, better absorption
- Fermentation: May enhance bioavailability
- Drying: Concentrated nutrients, good bioavailability
Food Combinations
- Fat addition: Essential for absorption
- Protein presence: Enhances absorption
- Fiber content: May reduce absorption
- Acid content: May enhance absorption
Individual Factors
Genetic Variations
- BCMO1 gene: Affects beta-carotene conversion
- RBP4 gene: Influences vitamin A transport
- CYP26 enzymes: Affects vitamin A metabolism
- Storage capacity: Individual differences in liver storage
Health Status
- Gut health: Affects absorption
- Liver function: Influences storage and metabolism
- Inflammation: May reduce absorption
- Medications: Can affect vitamin A metabolism
Age and Life Stage
- Infants: Higher absorption efficiency
- Children: Good absorption, high needs
- Adults: Stable absorption
- Elderly: Reduced absorption efficiency
Nutrient Interactions
Enhancing Factors
- Fat: Essential for absorption
- Protein: Supports transport and utilization
- Zinc: Required for vitamin A metabolism
- Iron: Enhances both nutrients
Inhibiting Factors
- Fiber: May reduce absorption
- Calcium: May compete for absorption
- Alcohol: Impairs vitamin A metabolism
- Smoking: Reduces beta-carotene conversion
Optimal Food Preparation
Cooking Methods
Steaming
- Benefits: Preserves nutrients, enhances bioavailability
- Temperature: Moderate heat, short time
- Water loss: Minimal nutrient loss
- Texture: Maintains crispness
Roasting
- Benefits: Enhances flavor, good bioavailability
- Temperature: Moderate to high heat
- Oil addition: Improves absorption
- Caramelization: Enhances sweetness
Sautéing
- Benefits: Quick cooking, good bioavailability
- Oil use: Essential for absorption
- Temperature: Medium heat
- Time: Short cooking time
Boiling
- Benefits: Simple method, good for soups
- Water loss: Some nutrients lost to water
- Temperature: High heat
- Time: Longer cooking time
Food Combinations
High Bioavailability Combinations
- Carrots + olive oil: Enhanced absorption
- Spinach + lemon: Iron + vitamin C
- Sweet potato + butter: Beta-carotene + fat
- Kale + nuts: Vitamin A + healthy fats
Meal Planning
- Breakfast: Fortified cereal + milk
- Lunch: Spinach salad + olive oil dressing
- Dinner: Roasted sweet potato + salmon
- Snacks: Carrot sticks + hummus
Storage and Preservation
Fresh Storage
- Refrigeration: Maintains nutrient content
- Dark storage: Protects from light degradation
- Moisture control: Prevents spoilage
- Temperature: Optimal storage conditions
Freezing
- Blanching: Preserves nutrients
- Quick freezing: Maintains quality
- Packaging: Prevents freezer burn
- Thawing: Gradual thawing preserves nutrients
Drying
- Dehydration: Concentrates nutrients
- Storage: Long-term preservation
- Rehydration: Restores some nutrients
- Quality: Maintains flavor and texture
Supplementation Considerations
When to Supplement
Deficiency Risk
- Limited animal products: Vegetarian/vegan diets
- Malabsorption: Medical conditions
- Increased needs: Pregnancy, lactation
- Poor dietary intake: Inadequate food sources
Supplement Forms
- Preformed vitamin A: More bioavailable
- Beta-carotene: Safer, no toxicity risk
- Mixed forms: Balanced approach
- Quality: Third-party tested products
Safety Considerations
Dosage Guidelines
- Prevention: RDA levels
- Treatment: Higher doses under supervision
- Maintenance: Based on individual needs
- Monitoring: Regular assessment
Toxicity Prevention
- Stay within UL: Respect upper limits
- Monitor intake: Track all sources
- Medical supervision: For high doses
- Regular testing: Blood levels and liver function
The Bottom Line
Getting vitamin A right isn't complicated—it's about choosing the right foods and eating them the right way. Here's what actually works:
Best Sources for Real Results:
- Liver (beef, chicken) - The ultimate vitamin A powerhouse
- Sweet potatoes - Easy to prepare, loaded with beta-carotene
- Spinach and kale - Perfect for salads and smoothies
- Eggs and dairy - Convenient and bioavailable
Skip & Fuel Strategy:
- Sunday refueling - Load up on vitamin A-rich foods after your 36-hour fast
- Cook with fat - A little butter or olive oil makes all the difference
- Eat the rainbow - Orange, yellow, and dark green foods are your friends
- Don't overthink it - Real food beats supplements every time
The key is consistency. A few servings of vitamin A-rich foods each week will keep your immune system strong and your energy stable—exactly what you need for sustainable weight loss.
Vitamin A: Cofactors and Essential Nutrients
Essential Cofactors for Vitamin A Function
1. Zinc
Role in Vitamin A Metabolism
- Retinol-binding protein (RBP) synthesis: Zinc is required for RBP production
- Hepatic mobilization: Zinc deficiency impairs vitamin A release from liver
- Intestinal absorption: Enhances vitamin A uptake
- Enzyme function: Required for retinol dehydrogenase activity
Biochemical Mechanisms
- RBP4 gene expression: Zinc-dependent transcription factors
- Protein synthesis: Essential for RBP production
- Enzyme cofactor: Multiple vitamin A-metabolizing enzymes
- Cellular transport: Facilitates vitamin A movement
Deficiency Effects
- Impaired vitamin A utilization: Despite adequate intake
- False deficiency: Low serum retinol with normal liver stores
- Night blindness: Without vitamin A deficiency
- Growth retardation: In children
Recommended Intake
- Adults: 8-11 mg/day
- Pregnancy: 11-12 mg/day
- Lactation: 12-13 mg/day
- Children: 3-8 mg/day (age-dependent)
Food Sources
- Oysters: Highest zinc content
- Red meat: Beef, lamb, pork
- Poultry: Chicken, turkey
- Seafood: Crab, lobster, shrimp
- Nuts and seeds: Pumpkin seeds, cashews
- Legumes: Chickpeas, lentils
2. Protein
Role in Vitamin A Transport
- RBP synthesis: Protein required for RBP production
- Transthyretin binding: Forms RBP-TTR complex
- Cellular uptake: Facilitates vitamin A entry into cells
- Storage proteins: Maintains vitamin A in tissues
Protein Quality Considerations
- Complete proteins: All essential amino acids
- Biological value: High-quality protein sources
- Digestibility: Affects amino acid availability
- Timing: Protein intake with vitamin A meals
Deficiency Effects
- Reduced RBP levels: Impaired vitamin A transport
- Tissue depletion: Despite adequate vitamin A intake
- Immune dysfunction: Compromised vitamin A function
- Growth failure: In children
Recommended Intake
- Adults: 0.8 g/kg body weight
- Pregnancy: +25 g/day
- Lactation: +25 g/day
- Children: 1.0-1.2 g/kg body weight
Food Sources
- Animal proteins: Meat, fish, poultry, eggs, dairy
- Plant proteins: Legumes, nuts, seeds, quinoa
- Combined sources: Rice and beans, hummus and pita
- Supplements: Protein powders, bars
3. Fat
Role in Vitamin A Absorption
- Solubility: Vitamin A is fat-soluble
- Micelle formation: Fat creates absorption environment
- Bile secretion: Fat stimulates bile production
- Lymphatic transport: Fat-soluble vitamin A transport
Types of Fat
- Saturated fats: Enhance absorption
- Monounsaturated fats: Olive oil, avocados
- Polyunsaturated fats: Omega-3 and omega-6
- Medium-chain triglycerides: Coconut oil
Optimal Fat Intake
- Minimum: 10-15% of calories from fat
- Optimal: 20-35% of calories from fat
- Timing: With vitamin A-rich meals
- Quality: Healthy fat sources
Skip & Fuel Hack: During my 36-hour fasts, I'd break my fast with a sweet potato roasted in butter and topped with a fried egg. The combination of beta-carotene, fat, and protein gave me sustained energy and kept my immune system strong. The cravings? They ghosted me by week 3 when I got this combination right.
Deficiency Effects
- Reduced absorption: Poor vitamin A uptake
- Tissue depletion: Despite adequate intake
- Deficiency symptoms: Night blindness, immune dysfunction
- Growth failure: In children
4. Iron
Role in Vitamin A Metabolism
- Enzyme cofactor: Required for retinol metabolism
- Oxygen transport: Supports vitamin A function
- Immune function: Both nutrients support immunity
- Growth and development: Essential for children
Biochemical Interactions
- Heme proteins: Iron-containing enzymes
- Oxidative metabolism: Iron-dependent processes
- Cellular respiration: Energy for vitamin A functions
- Antioxidant systems: Iron and vitamin A work together
Deficiency Effects
- Anemia: Reduced oxygen transport
- Impaired vitamin A utilization: Despite adequate intake
- Immune dysfunction: Both nutrients critical
- Growth retardation: In children
Recommended Intake
- Adult males: 8 mg/day
- Adult females: 18 mg/day (pre-menopause)
- Pregnancy: 27 mg/day
- Lactation: 9 mg/day
- Children: 7-15 mg/day (age-dependent)
Food Sources
- Heme iron: Meat, fish, poultry
- Non-heme iron: Legumes, spinach, fortified cereals
- Enhancers: Vitamin C improves absorption
- Inhibitors: Calcium, tannins reduce absorption
Supporting Nutrients
1. Vitamin D
Synergistic Effects
- Immune function: Both support immunity
- Bone health: Vitamin A and D work together
- Gene regulation: Both are nuclear receptor ligands
- Inflammation: Anti-inflammatory effects
Mechanisms
- Receptor interactions: VDR and RAR cooperation
- Gene expression: Coordinated regulation
- Cellular differentiation: Both essential
- Immune modulation: Complementary effects
Recommended Intake
- Adults: 600-800 IU/day
- Pregnancy: 600 IU/day
- Lactation: 600 IU/day
- Children: 400-600 IU/day
2. Vitamin E
Antioxidant Protection
- Free radical scavenging: Protects vitamin A from oxidation
- Membrane stability: Maintains cell membrane integrity
- Immune function: Both support immunity
- Tissue protection: Prevents vitamin A degradation
Mechanisms
- Antioxidant network: Vitamin E regenerates vitamin A
- Lipid peroxidation: Prevents vitamin A destruction
- Cellular protection: Maintains vitamin A function
- Immune enhancement: Synergistic effects
Recommended Intake
- Adults: 15 mg/day (22.4 IU)
- Pregnancy: 15 mg/day
- Lactation: 19 mg/day
- Children: 6-15 mg/day (age-dependent)
3. Vitamin C
Absorption Enhancement
- Iron absorption: Improves iron uptake
- Antioxidant protection: Protects vitamin A
- Collagen synthesis: Supports vitamin A functions
- Immune function: Both critical for immunity
Mechanisms
- Iron chelation: Forms absorbable iron complexes
- Antioxidant recycling: Regenerates vitamin E
- Collagen formation: Required for vitamin A functions
- Immune cell function: Both nutrients essential
Recommended Intake
- Adults: 65-90 mg/day
- Pregnancy: 85 mg/day
- Lactation: 120 mg/day
- Children: 15-75 mg/day (age-dependent)
4. B-Complex Vitamins
Energy Metabolism
- ATP production: Energy for vitamin A functions
- Enzyme cofactors: Required for vitamin A metabolism
- Protein synthesis: Essential for RBP production
- Cellular function: Support vitamin A activities
Specific B Vitamins
- B6 (Pyridoxine): Protein metabolism
- B12 (Cobalamin): DNA synthesis
- Folate: Cell division and growth
- Niacin: Energy metabolism
Recommended Intake
- B6: 1.3-1.7 mg/day
- B12: 2.4-2.8 μg/day
- Folate: 400-600 μg/day
- Niacin: 14-16 mg/day
Mineral Cofactors
1. Magnesium
Enzyme Function
- ATP utilization: Required for energy-requiring processes
- Protein synthesis: Essential for RBP production
- Cellular metabolism: Supports vitamin A functions
- Muscle function: Important for overall health
Recommended Intake
- Adult males: 400-420 mg/day
- Adult females: 310-320 mg/day
- Pregnancy: 350-360 mg/day
- Lactation: 310-320 mg/day
2. Selenium
Antioxidant Function
- Glutathione peroxidase: Protects vitamin A from oxidation
- Immune function: Both support immunity
- Thyroid function: Affects vitamin A metabolism
- Cellular protection: Maintains vitamin A function
Recommended Intake
- Adults: 55 μg/day
- Pregnancy: 60 μg/day
- Lactation: 70 μg/day
- Children: 15-55 μg/day (age-dependent)
3. Copper
Enzyme Cofactor
- Superoxide dismutase: Antioxidant protection
- Iron metabolism: Affects vitamin A function
- Collagen synthesis: Supports vitamin A functions
- Immune function: Both critical for immunity
Recommended Intake
- Adults: 900 μg/day
- Pregnancy: 1,000 μg/day
- Lactation: 1,300 μg/day
- Children: 200-900 μg/day (age-dependent)
Nutrient Interactions and Timing
Meal Timing
- Fat with vitamin A: Enhances absorption
- Protein with vitamin A: Supports utilization
- Zinc with vitamin A: Improves function
- Iron with vitamin A: Enhances both nutrients
Food Combinations
- Carrots with olive oil: Beta-carotene + fat
- Spinach with lemon: Iron + vitamin C
- Sweet potato with butter: Beta-carotene + fat
- Liver with vegetables: Preformed vitamin A + cofactors
Supplement Timing
- With meals: Enhances absorption
- Fat-soluble vitamins together: A, D, E, K
- Mineral cofactors: Zinc, iron, magnesium
- Avoid with: Calcium, fiber (may reduce absorption)
Deficiency Patterns
Primary Deficiencies
- Vitamin A alone: Rare in developed countries
- Zinc alone: Common in developing countries
- Protein alone: Kwashiorkor, marasmus
- Iron alone: Most common nutrient deficiency
Multiple Deficiencies
- Vitamin A + Zinc: Common in developing countries
- Vitamin A + Protein: Malnutrition
- Vitamin A + Iron: Anemia + night blindness
- All nutrients: Severe malnutrition
Treatment Considerations
- Address all deficiencies: Not just vitamin A
- Gradual correction: Avoid toxicity
- Monitor interactions: Nutrient competition
- Long-term follow-up: Prevent recurrence
The Real-World Take
Here's the thing about vitamin A cofactors—you don't need to memorize a biochemistry textbook. You just need to eat real food consistently.
The Essential Trio:
- Zinc - Found in meat, seafood, and nuts
- Protein - Every meal should have some
- Fat - Cook your vegetables with oil or butter
Skip & Fuel Practical Approach:
- Sunday meal prep - Include zinc-rich foods like beef or chicken
- Add healthy fats - A drizzle of olive oil on your spinach salad
- Don't skip protein - It's not just for building muscle
- Keep it simple - Real food has everything you need
The cravings? They ghosted me by week 3 when I got my nutrition dialed in. Vitamin A and its cofactors were a big part of that success.
Ready to Get Your Vitamin A Right?
This is exactly the approach I used to drop 17kg—36-hour weekend fasts (Friday 8pm to Sunday 8am), keto refueling on Sundays, and zero misery. The Skip & Fuel app will help you track your nutrition, including vitamin A-rich foods and their cofactors, with practical meal planning and real support.
Join the waitlist to be first in line when we launch.
About the Author: Skip & Fuel was created by someone who lost 17kg in 6 months using the 36-hour weekend fasting approach. Real results, real strategies—no BS.
About Skip & Fuel Team
Skip & Fuel was created by someone who lost 17kg in 6 months using the 36-hour weekend fasting approach. Real results, real strategies—no BS. This isn't theory, it's what actually worked for sustainable weight loss.