Do potatoes and split peas make a complete protein?

November 7, 2025 •

3 min read

The idea that certain plant-based foods must be meticulously combined in a single meal to form a complete protein has been largely debunked by nutrition experts for decades. This myth, however, prompts a valid question: do potatoes and split peas make a complete protein, and is this pairing still a nutritious strategy for a balanced diet?

Quick Summary

This article explores the amino acid profiles of potatoes and split peas, clarifying why they are a valuable protein combination and explaining that a diverse, plant-based diet is sufficient for obtaining all essential amino acids.

Key Points

Combining Myth Debunked: The idea of combining complementary plant proteins in the same meal is outdated; the body uses an amino acid pool from daily intake.
Potatoes are Complete Proteins: Potatoes contain all nine essential amino acids.
Split Peas are Protein-Rich: Split peas are an excellent source of high-quality plant protein.
Powerful Nutritional Combo: Eating potatoes and split peas together creates a nutrient-dense, high-protein meal.
Focus on Variety: A diverse daily diet of whole plant foods ensures you get all essential amino acids.
Not Required but Beneficial: While combining isn't necessary for completeness, the potato-split pea pairing is a smart choice for a satisfying and healthy plant-based meal.

The 'Protein Combining' Myth and Modern Nutrition

For decades, a popular belief persisted that vegans and vegetarians needed to combine 'incomplete' plant proteins in the same meal to get all nine essential amino acids (EAAs). This idea suggested specific plant sources lacked sufficient amounts of one or more EAAs.

Understanding Essential Amino Acids

Proteins are made of amino acids, nine of which are 'essential' because they must come from our diet. A 'complete' protein has enough of all nine EAAs. While most animal proteins are complete, it's now understood that all plant foods contain all nine EAAs, though amounts can vary.

Dispelling the Timing Myth

Crucially, your body doesn't need all essential amino acids at once. It maintains an amino acid pool from foods eaten throughout the day. A diverse plant-based diet with legumes, grains, nuts, and vegetables provides all necessary protein.

The Nutritional Profile of Potatoes and Split Peas

Both potatoes and split peas contribute significantly to a plant-based diet.

Protein in Potatoes

A large baked potato contains about 8 grams of protein and all nine essential amino acids, making it a complete protein on its own, though not protein-dense. Potatoes also offer fiber, potassium, and vitamins.

Protein in Split Peas

Split peas are a protein-rich legume, high in lysine but typically lower in methionine. A cup of cooked lentils, similar to split peas, has about 18 grams of protein. They are also high in fiber, folate, and manganese.

How Potatoes and Split Peas Complement Each Other

Combining potatoes and split peas makes a nutrient-dense meal. Split peas add ample protein, while the potato's complete profile (including methionine) complements the peas. This pairing is great for protein, fiber, vitamins, and minerals.

Comparing Plant-Based and Animal-Based Protein Sources


Feature	Plant-Based Proteins (e.g., Potatoes & Split Peas)	Animal-Based Proteins (e.g., Chicken & Beef)
Complete Protein?	Yes, when varied over the day; some individual plants are complete.	Yes, most individual animal products are complete.
Saturated Fat	Generally low or absent.	Often high.
Fiber Content	High.	None.
Micronutrients	Wide range of vitamins, minerals, and phytonutrients.	Often higher in vitamin B12 and iron (heme).
Environmental Impact	Generally lower.	Generally higher.

Other Valuable Complete Protein Pairings (Over the Day)

A varied diet is key for all essential amino acids. Here are some examples of complementary pairings eaten throughout the day:

Grains and Legumes: Beans and rice, hummus and pita.
Legumes and Seeds: Bean salad with sunflower seeds, lentil soup with walnuts.
Grains and Nuts: Peanut butter on whole-grain bread, oatmeal with nuts.
Green Veggies: Spinach and broccoli contain all essential amino acids.

Conclusion

Yes, potatoes and split peas provide a complete protein profile when eaten together, primarily because potatoes contain all essential amino acids and split peas are high in protein. However, it's not necessary to combine them in one meal due to the debunking of the protein-combining myth. A diverse daily diet of whole plant foods supplies all needed essential amino acids. A meal of potatoes and split peas is a excellent nutritional choice, one of many ways to get high-quality plant protein. For more on plant-based nutrition, see sources like The Nutrition Source at Harvard University.

Frequently Asked Questions

No, this is a myth. All plant foods contain all nine essential amino acids, although amounts may vary. The body's amino acid pool makes up for daily variations.

No. Your body combines essential amino acids from different meals throughout the day. Focus on a varied diet rather than specific pairings per meal.

Yes, potatoes contain all nine essential amino acids. They are not high in protein by volume, so include other dense protein sources.

Legumes, including split peas, are typically lower in methionine compared to grains. Traditional grain-and-legume pairings addressed this, though it's not needed in a single meal.

Examples include rice and beans, hummus and pita, or chickpeas and sunflower seeds. A varied diet of whole plant foods over the day is key.

Both can provide sufficient protein. Plant proteins often offer more fiber and less saturated fat. A varied diet is crucial.

Combining them makes a nutrient-rich, high-protein meal. The protein density of peas complements the amino acids in potatoes, creating a satisfying dish with fiber, vitamins, and minerals.