Which Amino Acid is Not in Moong Dal? The Complete Protein Profile

November 20, 2025 •

3 min read

While often lauded as a high-protein food source, the fact is that moong dal, like most legumes, is deficient in certain essential amino acids and is therefore not a 'complete' protein on its own. The specific amino acids that are limited in moong dal are methionine and cysteine.

Quick Summary

Moong dal is notably low in the sulfur-containing amino acids methionine and cysteine, which is why it is not considered a complete protein source by itself.

Key Points

Methionine and Cysteine Deficiency: Moong dal, like most legumes, is limited in the sulfur-containing amino acids methionine and cysteine, making it an incomplete protein source on its own.
Not Absent, but Low: The amino acids are not entirely absent from moong dal but are present in nutritionally inadequate amounts when compared to a complete protein source.
Complementary Proteins: The solution is to combine moong dal with a food rich in methionine and cysteine, such as a cereal grain like rice, to form a complete protein meal.
Lysine-Rich: Moong dal is an excellent source of the essential amino acid lysine, which often balances out deficiencies found in grains.
Balanced Diet is Simple: Achieving a complete amino acid profile is simple through a varied diet, as demonstrated by traditional dishes like dal and rice.

Understanding the 'Incomplete' Protein Status

To properly answer the question, "Which amino acid is not in moong dal?", it is essential to understand the difference between complete and incomplete proteins. Complete proteins contain all nine essential amino acids that the human body cannot produce on its own. Incomplete proteins, like moong dal, are low in or lack one or more of these essential amino acids.

While moong dal contains a good quantity of protein, its nutritional profile is limited by the low content of specific sulfur-containing amino acids, primarily methionine and cysteine. This is a common characteristic among most pulses and legumes. However, it is not correct to say that moong dal contains no methionine or cysteine, but rather that its levels are nutritionally inadequate when consumed as a sole protein source.

The Role of Essential Amino Acids

Amino acids are the building blocks of protein, which is vital for building and repairing tissues, making enzymes and hormones, and overall bodily function. The nine essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. For vegetarians and vegans, understanding which plant foods are rich or low in these is key to creating a balanced diet.

Moong dal is actually rich in other essential amino acids like lysine, making it an excellent complementary protein to grains, which are often rich in methionine but low in lysine. Combining these two food groups, like in the traditional Indian dish dal and rice, creates a complete protein profile.

The Power of Complementary Proteins

Creating a complete protein by combining different plant-based foods is a well-established nutritional strategy. This concept is simple: if one food is low in a specific amino acid, combine it with another food that is rich in that amino acid. This ensures the body receives all nine essential amino acids.

Examples of Complementary Protein Combinations

Dal and Rice: A classic combination in many cultures. Moong dal provides ample lysine, while rice supplies the necessary methionine, creating a complete protein meal.
Moong Dal and Whole Wheat Roti: Similar to the rice pairing, whole wheat roti or bread complements moong dal perfectly to form a complete protein.
Moong Dal and Nuts/Seeds: Adding nuts or seeds, like almonds or sunflower seeds, to moong dal-based salads or dishes can help boost the methionine and cysteine content.

Comparison of Moong Dal and Grains


Amino Acid	Moong Dal (High in)	Grains (Rich in)	Complete Profile (Combined)
Methionine	Low	High	Balanced
Cysteine	Low	High	Balanced
Tryptophan	Inadequate	High	Balanced
Lysine	High	Low	Balanced
Other EAAs	Sufficient	Varies	Balanced

Nutritional Enhancement and Processing

Interestingly, some research shows that processes like germination can affect the amino acid profile of mung beans. For instance, germination can increase certain amino acid levels, while cooking methods can sometimes cause slight reductions in sulfur-containing amino acids like methionine and cysteine. For optimal nutrition, a varied diet is always recommended, and combining different plant proteins is a simple and effective strategy.

For a deeper look into the specific nutritional and functional properties of mung bean proteins and peptides, including their amino acid composition, a comprehensive review published in Food & Nutrition Research provides valuable data.

Conclusion

While no single essential amino acid is entirely absent from moong dal, its nutritional profile is characterized by a low concentration of the sulfur-containing amino acids methionine and cysteine. This means that on its own, moong dal is an 'incomplete' protein source. However, this is not a nutritional weakness, but rather a simple fact of its plant-based origin. By pairing moong dal with other foods that are rich in the limited amino acids, such as grains like rice or wheat, one can easily create a complete protein meal. This practice is already a foundation of many traditional cuisines and is a delicious way to ensure comprehensive nutrition.

Combining foods is key

The strategic combination of different protein sources is a fundamental principle of balanced plant-based nutrition, ensuring all essential amino acids are obtained throughout the day. This makes dishes featuring moong dal both healthy and satisfying. Remember, the goal is not to eliminate foods with incomplete protein profiles but to complement them wisely within a diverse diet.

Frequently Asked Questions

No, moong dal does not contain zero methionine. It is simply low in this particular amino acid, which makes it an incomplete protein source on its own.

An incomplete protein is a food that contains some, but not all, of the nine essential amino acids that the human body cannot produce. To get a full profile, it must be combined with other foods.

You can make moong dal a complete protein by combining it with foods that contain the amino acids it is low in, such as cereals like rice or roti. A traditional dish of dal and rice is a perfect example.

Yes, some studies indicate that tryptophan is also present in nutritionally inadequate levels in mung bean protein when compared against reference patterns.

Most legumes are deficient in the sulfur-containing amino acids methionine and cysteine, although the exact levels can vary. This is a common characteristic of the legume family.

While sprouting can increase certain nutrient levels in mung beans, it does not fundamentally change their amino acid profile enough to make them a complete protein source on their own. They will still be low in methionine and cysteine.

No, it is not necessary to eat complementary proteins in the same meal. The body has a pool of amino acids, and consuming different protein sources throughout the day is sufficient to provide all essential amino acids.