Kakadu Plum Seed — What’s Inside the Kernel

The Kakadu plum is one fruit with two completely different nutritional stories — and most supplements tell only one of them.

The story everyone knows: the fruit flesh holds the highest recorded natural vitamin C of any plant on earth. Our independently lab-tested powder measures 12,100mg per 100g — more than 240 times the concentration of a fresh orange.

The story almost nobody tells: the seed kernel holds the four minerals the body needs to turn that vitamin C signal into actual collagen.

Most Kakadu plum suppliers remove the seed before they powder the fruit. Some brands market this as a feature: “NO SEED = more Kakadu plum” or “Seed-free!” It is true that removing the seed raises the vitamin C concentration per gram. What it leaves behind is the mineral co-machinery that vitamin C depends on.

Kakadu Plum Capsules — whole fruit and seed, 64 cents each →

The Seed Completes the Collagen Picture

Building collagen in the body is not a single-step process. It requires a set of co-factors working together. Vitamin C activates the synthesis enzymes and signals fibroblasts — the cells in skin and connective tissue — to produce collagen. But vitamin C cannot complete this process alone. It requires four mineral co-factors: iron, zinc, copper and manganese. [1]

These four minerals are the machinery that vitamin C sets in motion. Without them, the signal is sent but the work is not completed.

Here is where each co-factor sits in the two parts of the fruit:

The fruit brings vitamin C and vitamin E. The seed brings iron, zinc, copper and manganese — at levels 2 to 10 times higher than the flesh. In a whole fruit capsule, both parts are present. In a de-seeded powder, only the fruit column exists.

Source: DePhillipo NN et al., Orthopaedic Journal of Sports Medicine 2018 (PMC6204628, cited 350 times) for the co-factor roles. RIRDC Australian Government Pub. 09/133 (2009) and Akter et al. Foods 2018 (PMC5920425) for the Kakadu plum figures. FSANZ approved wording: “Vitamin C contributes to normal collagen formation for the normal function of skin.” [1][2][3]

What Is the Kakadu Plum Seed Kernel?

The seed is the woody structure inside the fruit. Inside the seed is the kernel — the inner core that holds the nutritional value. The kernel makes up about 8% of the seed’s weight. In practical terms: every 100 kg of fruit produces about 22 kg of seed, and the kernel is the dense interior once the shell is removed.

The seed coat — the outer shell — has very little nutritional value: about 0.1 to 0.3g of phenolics per 100g and minimal tannins. [4] The goodness is in the kernel. When we say “whole fruit including seed kernel,” that is what we mean.

Full Nutritional Profile of the Seed Kernel

The kernel has been measured by two independent studies: the Australian Government’s RIRDC report in 2009 (Pub. 09/133) and a dedicated 2018 peer-reviewed study specifically on the kernel (Akter et al., Foods, PMC5920425). Both concluded the kernel “could be a new protein source.”

Macronutrients (per 100g dried kernel)

• Protein: 32% — above chickpeas (19%), above lentils (25%), approaching soybeans (36%). The protein content also means magnesium naturally bonds to amino acid side chains in the food matrix — the same mechanism chelated supplements like magnesium glycinate try to replicate synthetically.
• Fat: 35% — about 80% unsaturated
• Fibre: 21%
• Energy: 2,065 kJ per 100g

The Fat Profile

• Linoleic acid (omega-6): 50.2% of the fat — the polyunsaturated fat found in sunflower and flaxseed oils
• Oleic acid: 29.2% of the fat — the same monounsaturated fat that accounts for about 73% of olive oil and about 65% of avocado. Present in an Australian seed most people have never heard of.
• Palmitic acid: 12.0% — saturated, same family as palm oil and butter
• Stearic acid: 7.2% — saturated, found in dark chocolate and beef fat
• About 4 in every 5 grams of fat in the kernel is unsaturated

Minerals (per 100g dried kernel)

Heavy metals were measured and found low: lead 0.013mg per 100g; arsenic, mercury and cadmium each below 0.01mg per 100g. [2]

Why Nearly Every Supplier Removes the Seed

The commercial logic is straightforward. Kakadu plum powder has been sold as a vitamin C ingredient since the 1990s. The vitamin C is in the fruit flesh. The seed is not where the vitamin C lives — so suppliers who optimise for vitamin C concentration remove the seed, because including it dilutes the number.

Some brands now explicitly use “NO SEED” or “Seed-free!” as a selling point, framing removal as a mark of quality. Their argument: without the seed, you get more vitamin C per gram of powder.

That argument is correct on its own terms. A de-seeded powder does have higher vitamin C per gram.

What the argument does not address is what leaves with the seed: the four mineral co-factors that vitamin C needs to build collagen — zinc at 10× the level in the flesh, copper at 8×, manganese at 2.6×, iron at 50% more. Alongside that: calcium at 539mg per 100g, magnesium at 421mg, protein at 32%, and a fat profile mostly composed of the same unsaturated fats found in olive oil and avocado.

The RIRDC 2009 Australian Government report measured the mineral profile of the seed kernel. The dedicated 2018 peer-reviewed study concluded the kernel “could be a new protein source.” Most Kakadu plum supplement makers have not read these papers. Their processing decisions were made when the only question anyone was asking about the fruit was how much vitamin C it had.

Oxalate — Does the Seed Add More?

Whole fruit including seed measured 2,633 to 2,717mg of oxalate per 100g dried. Puree with most seeds removed measured 2,466 to 2,573mg. [5] The seeds barely change the oxalate level.

For context: a 500mg capsule of whole fruit powder contains about 7 to 14mg of oxalate — about the same as one cup of raspberries. Cooked spinach at the same serve size contains around 35 to 70 times more.

If you have a history of kidney stones, speak to your health professional before adding any high-vitamin C food to your routine, as the body converts some vitamin C to oxalate.

How Our Capsules Use Whole Fruit

Our Kakadu plum capsules use whole fruit powder — fruit and seed kernel ground together to the same fine, consistent powder. The seed kernel is processed to the same standard as the fruit flesh. That costs more and takes more time.

We do it because the seed kernel is the most mineral-dense part of the plant, and leaving it out means leaving out the four mineral co-factors that complete the collagen story the vitamin C starts.

Kakadu Plum Capsules — whole fruit and seed, 140 capsules, 64 cents each →

For the full science on vitamin C and collagen, see our collagen page. For the full magnesium comparison including serving sizes, see our magnesium page. For the 11 named tannins in the fruit, see our tannins page.

Frequently Asked Questions

What is the Kakadu plum seed?

Inside every Kakadu plum fruit is a seed, and inside the seed is the kernel — a dense inner core that makes up about 8% of the seed’s weight. Every 100 kg of fruit produces about 22 kg of seed. In commercial processing the kernel is almost always removed. In whole fruit powder it is ground together with the fruit flesh. The seed coat (the outer shell) has very few nutrients — the goodness is in the kernel.

Can you eat Kakadu plum seeds?

The seed kernel is edible. Australian Government researchers (RIRDC 2009) and a dedicated 2018 peer-reviewed study (Akter et al., Foods) measured its full nutritional profile and concluded it could be a new protein source. At 32% protein, 35% fat and 21% fibre the kernel is nutritionally dense. Heavy metals were measured and found low: lead 0.013mg per 100g, arsenic, mercury and cadmium each below 0.01mg per 100g.

Why do most Kakadu plum powders not contain the seed?

Removing the seed raises the vitamin C concentration per gram — the ascorbic acid is in the fruit flesh, not the seed. Some suppliers market this directly: “NO SEED = more Kakadu plum” or “Seed-free!” The trade-off is that the seed kernel carries most of the fruit’s mineral content — iron, zinc, copper and manganese at levels 2 to 10 times higher than the fruit flesh. These minerals are required co-factors for collagen synthesis (DePhillipo 2018, cited 350 times). Removing the seed optimises one nutrient while discarding the rest.

What nutrients are in the Kakadu plum seed kernel?

Per 100g dried kernel (RIRDC 2009, Akter et al. Foods 2018): Protein 32%, Fat 35% (about 80% unsaturated), Fibre 21%. Minerals: Phosphorus 873mg, Potassium 669mg, Calcium 539mg, Magnesium 421mg, Iron 6.1mg, Zinc 6.0mg, Manganese 9.1mg, Copper 2.5mg, Sodium 120mg. The dominant fats are linoleic acid (omega-6, 50%) and oleic acid (29%) — the same monounsaturated fat that accounts for most of olive oil.

What is the connection between the Kakadu plum seed and collagen?

Building collagen requires six co-factors. Vitamin C (from the fruit flesh) activates the synthesis enzymes and signals fibroblasts to produce collagen. The four mineral co-factors — iron, zinc, copper and manganese — are the building machinery. In the Kakadu plum, these are concentrated in the seed kernel. Zinc is 10 times higher in the seed than in the flesh. Copper is 8 times higher. Manganese is 2.6 times higher. Iron is 50% higher. A whole fruit capsule delivers vitamin C alongside all four mineral co-factors.

Is the Kakadu plum seed high in protein?

At 32% protein by weight the dried kernel sits above chickpeas (about 19%), lentils (about 25%) and approaches soybeans (about 36%). Australian Government researchers described it as a potential new protein source. The high protein content also means magnesium naturally bonds to amino acid side chains in the food matrix — the same mechanism chelated magnesium supplements like glycinate try to replicate synthetically.

Is whole fruit Kakadu plum powder better than de-seeded?

Neither is objectively better — they are different products with different nutritional profiles. De-seeded powder optimises for vitamin C per gram: removing the seed raises the concentration. Whole fruit powder includes the seed kernel’s minerals, protein and fatty acids alongside the fruit’s vitamin C, tannins and polyphenols. If vitamin C is the only goal, de-seeded is more efficient. If you want the complete nutritional profile of the plant — including the mineral co-factors for collagen synthesis alongside the vitamin C — whole fruit includes all of it.

References

1. DePhillipo NN et al. Efficacy of Vitamin C Supplementation on Collagen Synthesis and Oxidative Stress After Musculoskeletal Injuries. Orthopaedic Journal of Sports Medicine, 2018. PMC6204628. Cited by 350 studies.
2. Akter S et al. Chemical and Nutritional Composition of Kakadu Plum Kernels. Foods, 2018. PMC5920425.
3. Konczak I et al. Health Benefits of Australian Native Foods. RIRDC Australian Government Pub. No. 09/133, Sept 2009.
4. Akter S et al. Antioxidant Rich Extracts of Terminalia ferdinandiana Inhibit the Growth of Foodborne Bacteria. Foods, 2019. PMC6724055. (Seed coat phenolic data.)
5. Williams DJ et al. Organic acids in Kakadu plum. Food Research International, 2016. (Oxalate data.)

For the plant protein comparison — where the seed’s 32% sits against chickpeas, lentils, soy, and hemp — see our plant based protein page.

Our products are food, not therapeutic goods, and are not intended to diagnose, treat, cure or prevent any disease or condition.