The Bioavailability Gap: Why You Are Eating the Right Foods and Getting the Wrong Results

The Gap Nobody Talks About

Nutritional science has spent decades telling us what to eat. Eat more vegetables. Eat less processed food. Get your Omega-3s. Increase your fibre. The advice is broadly correct — but it is incomplete. Because the question is not just what nutrients are present in your food. It is what nutrients your body actually absorbs.

The difference between these two things is what we call the Bioavailability Gap.

Consider iron. Spinach is famously rich in iron — a fact so well-established it became the basis of a cartoon character. But the iron in spinach is non-haem iron, which has a bioavailability of approximately 2–8% in isolation. Eat spinach with a source of Vitamin C (lemon juice, red pepper, tomato) and that bioavailability rises to 15–20%. Eat it with tea or coffee within an hour, and it drops back to near zero. The spinach has not changed. The iron content has not changed. Only the context has changed — and the context determines the outcome.

This is not an edge case. It is the rule. Almost every nutrient in plant food has a bioavailability that varies dramatically depending on what you eat it with, how you prepare it, and what you eat before and after it.

The Four Keys

Through the research that underpins Root & Reason, we have identified four categories of compounds that determine nutrient bioavailability:

Unlockers are compounds that break open plant cell walls, releasing nutrients that would otherwise pass through the digestive system intact. The most powerful Unlocker we know of is mustard seed powder — which restores the enzyme needed to produce sulforaphane from cooked cruciferous vegetables, increasing yield by 400%. Other Unlockers include heat (which breaks down cell walls in many vegetables), mechanical disruption (chopping, blending, chewing), and fermentation (which pre-digests plant material, releasing nutrients that human digestive enzymes cannot access).

Carriers are healthy fats that transport fat-soluble nutrients into the bloodstream. Vitamins A, D, E, and K are all fat-soluble — they cannot be absorbed without fat present in the same meal. Carotenoids (beta-carotene, lycopene, lutein) are fat-soluble. Curcumin is fat-soluble. Eating a salad with fat-free dressing and expecting to absorb the fat-soluble nutrients is like trying to dissolve sugar in oil — the chemistry simply does not work. Olive oil, avocado, nuts, seeds, ghee, and oily fish are all Carriers.

Converters are acids that change the chemical form of minerals, making them soluble and absorbable. Non-haem iron (from plant sources) exists in the Fe³⁺ form, which the gut cannot absorb. Vitamin C converts it to Fe²⁺, which the gut can. Apple cider vinegar acidifies the stomach, improving the absorption of calcium, magnesium, and zinc. Lemon juice on leafy greens is not just a flavour choice — it is a Converter at work.

Catalysts are compounds that dramatically amplify the potency of other nutrients. Black pepper's piperine is the most dramatic example — increasing curcumin bioavailability by 2,000%. But there are others: quercetin (found in onions and apples) enhances the absorption of resveratrol; Vitamin D dramatically increases calcium absorption; Vitamin C regenerates Vitamin E after it has been oxidised, effectively recycling it.

The Inhibitors

Just as important as the Activators are the Inhibitors — compounds that block nutrient absorption. The most significant are:

Tannins (in tea, coffee, and red wine) bind to iron and zinc, forming insoluble complexes that cannot be absorbed. The 60-Minute Rule — avoiding tea and coffee for one hour after iron-rich or mineral-rich meals — is one of the simplest and most impactful dietary changes most people can make.

Phytates (in raw grains, legumes, and seeds) bind to calcium, zinc, magnesium, and iron. Soaking, sprouting, or fermenting grains and legumes dramatically reduces phytate content — which is why traditionally prepared foods (sourdough bread, soaked oats, sprouted lentils) are more nutritious than their unprocessed equivalents.

Oxalates (in spinach, beet greens, and rhubarb) bind to calcium, reducing its absorption. Cooking reduces oxalate content significantly — raw spinach is actually a poorer source of bioavailable calcium than cooked spinach, despite having a higher total calcium content.

The Root & Reason Approach

Every Root & Reason Bio-Box is built around the Bioavailability Gap. The ingredients are selected not just for their nutrient content, but for their activation potential — the degree to which they unlock, carry, convert, and catalyse each other. The recipes are designed to apply the protocols that maximise absorption. The educational content — including The Mustard Seed Secret eBook and the Resources Hub — explains the science so that customers understand not just what to eat, but why the preparation matters.

You are not what you eat. You are what you absorb. And the gap between those two things is where Root & Reason lives.