When fitness researchers talk about plant based protein, they compare chickpeas, lentils, soy, and hemp. The Kakadu plum seed — ground into Australia’s most studied native fruit — measures at 32% protein by dry weight in a peer-reviewed study. The researchers’ own conclusion: the kernel could be a new protein source.
This page shows where that figure sits against the rest of the plant kingdom, and why the seed brings more to the table than protein alone.
Real McArthur Kakadu Plum Capsules — whole fruit including the seed, grown and made in Australia.
Plant Based Protein — Where the Kakadu Plum Seed Sits
| Plant protein source | Protein per 100g dried | Source |
|---|---|---|
| Soybeans | 36% | USDA FoodData Central |
| Kakadu plum seed | 32% — peer-reviewed | Akter et al. 2018 |
| Pumpkin seeds | 30% | USDA FoodData Central |
| Hemp seeds | 25% | USDA FoodData Central |
| Lentils | 25% | USDA FoodData Central |
| Chickpeas | 19% | USDA FoodData Central |
| Quinoa | 14% | USDA FoodData Central |
Source: Akter MS et al. Nutritional compositions and bioactive compounds of three native Australian fruits. 2018. PMC5920425.
What the Seed Has That Protein Powder Doesn’t
Protein isolates give you a concentrated dose of one nutrient. The Kakadu plum seed is a whole food — 32% protein alongside 35% fat (four-fifths of it unsaturated) and a mineral panel that covers the nutrients directly involved in protein synthesis and energy metabolism.
| Nutrient in the seed | Per 100g dried | Known role |
|---|---|---|
| Protein | 32g | Core building block for muscle tissue maintenance |
| Magnesium | 421mg | Co-factor in over 300 enzyme systems; required for muscle contraction and energy production [NIH] |
| Phosphorus | 873mg | Core component of ATP — the molecule that powers every muscle contraction |
| Iron | 6.1mg | Carries oxygen in the blood to working muscles |
| Zinc | 6.0mg | Required for normal protein synthesis |
| Oleic acid | 29% of total fat | The monounsaturated fat found in olive oil and avocado |
| Linoleic acid (omega-6) | 50% of total fat | Essential fatty acid |
None of this is assembled. It grows this way.
The magnesium in the seed arrives in its natural food form. Because the seed is 32% protein, the magnesium is naturally bonded to amino acids in the food matrix — the same mechanism that chelated magnesium supplements (glycinate, malate) replicate synthetically. You get it from the food, not from a lab.
The Amino Acid Question — What We Know and What We Don’t
The specific amino acid breakdown of the Kakadu plum seed has not been published. The 2018 paper measured total protein content at 32% but did not run an amino acid profile. We will not guess.
What the research does say: the same authors concluded the kernel “could be a new protein source,” and the overall protein content sits above lentils, chickpeas, hemp, and quinoa by mass.
For now, the seed is best understood as a whole-food plant protein source — 32%, peer-reviewed, Australian-grown. The amino acid work is ongoing in the scientific literature.
Why Whole Food Beats a Supplement Stack
Most gym supplement stacks include a protein powder, a magnesium tablet, a zinc supplement, and an omega-3 capsule. Separate products, separate bills, separate manufacturing.
The Kakadu plum seed contains protein, magnesium, zinc, iron, phosphorus, omega-6 fat, and oleic acid — occurring together in a single food, measured in a peer-reviewed paper, grown on a farm in Australia.
It will not replace a diet. But as a whole-food source of plant based protein with the minerals that support it, there is nothing else like it in the Australian food supply.
How Real McArthur Uses the Whole Fruit
Most Kakadu plum processors remove and discard the seed. The fruit flesh holds the vitamin C; the seed holds the protein and minerals. Removing it is faster and cheaper.
Real McArthur uses the whole fruit — flesh and seed ground together. Each capsule delivers both nutrient profiles: the 12,100mg/100g vitamin C from the flesh, and the 32% protein, 421mg magnesium, and four collagen mineral co-factors from the seed.
See the Kakadu Plum Capsules →
For the full mineral breakdown of the seed, including the four co-factors the body uses to build collagen, see our Kakadu plum seed page.
Frequently Asked Questions — Plant Based Protein
What plant foods are highest in protein?
By dry weight: soybeans (36%), Kakadu plum seed (32%, peer-reviewed), pumpkin seeds (30%), hemp seeds and lentils (25%), and chickpeas (19%). The Kakadu plum seed is the most overlooked plant protein source in this range — never commercially available as a standalone protein food, only as part of the whole fruit.
Is plant protein as good as animal protein?
Animal proteins contain all nine essential amino acids in higher proportions. Plants vary — soybeans are considered a complete protein; others work best when combined across meals. The Kakadu plum seed’s specific amino acid profile has not been published yet. By overall protein content at 32%, it sits between lentils and soybeans and is within the range of commonly used plant protein sources.
What is the Kakadu plum seed, and why is it high in protein?
The Kakadu plum seed is the kernel inside the fruit’s hard stone, making up about 8% of the seed weight. Researchers measured it at 32% protein by dry weight in a 2018 peer-reviewed study and noted it could be a new protein source. Most suppliers discard the seed during processing. Real McArthur grinds the whole fruit, stone and seed included.
How does the Kakadu plum seed compare to pea or soy protein powder?
Isolated pea or soy protein powder typically measures 70 to 90% protein — but only because everything else has been extracted. The Kakadu plum seed at 32% compares to unprocessed soybeans before isolation. The practical difference: the seed delivers protein alongside 421mg magnesium, 6mg zinc, 6mg iron, and 873mg phosphorus per 100g — nutrients stripped out during protein isolation.
What minerals does the Kakadu plum seed contain alongside its protein?
Per 100g dried kernel: magnesium 421mg, phosphorus 873mg, potassium 669mg, calcium 539mg, iron 6.1mg, zinc 6.0mg, copper 2.5mg, and manganese 9.1mg. Magnesium, iron, zinc, and copper are the four minerals directly involved in collagen synthesis — the same pathway that uses vitamin C from the fruit flesh. See our full seed mineral breakdown.
Can you get all essential amino acids from plant sources?
Yes — eating a variety of plant foods across the day covers all nine essential amino acids. The Kakadu plum seed’s specific amino acid profile has not been published, so we describe it by overall protein content at 32% rather than claim amino acid completeness. Anyone relying on plant sources exclusively should vary their diet: legumes, grains, seeds, and nuts fill different gaps.
Is the Kakadu plum seed safe to eat?
Yes. The 2018 study measured heavy metal content: lead was 0.013mg per 100g, and arsenic, mercury, and cadmium were each below 0.01mg per 100g — all well within food safety limits. Oxalate in the seed is lower than in the fruit flesh. If you have a history of kidney stones or take prescription medications, check with your health professional before adding any high-nutrient food supplement to your diet.
References
- Akter MS, Oh S, Eun J-B, Ahmed M. Nutritional compositions and bioactive compounds of three native Australian fruits. International Journal of Food Science and Nutrition. 2018. PMC5920425.
- DePhillipo NN et al. Efficacy of Vitamin C Supplementation on Collagen Synthesis and Oxidative Stress After Musculoskeletal Injuries. Orthopaedic Journal of Sports Medicine. 2018;6(10). PMID 30386805.
- NIH Office of Dietary Supplements. Magnesium Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
- USDA FoodData Central. fdc.nal.usda.gov