You Are What You Absorb

"You are what you eat," the saying goes. But it isn't quite true. You are what you absorb. Someone can eat a beautiful, organic, home-cooked diet and still be running low on iron, vitamin B12, zinc or magnesium, simply because their digestion isn't breaking down and taking in what's on their plate. Often the first clues are easy to dismiss: a little bloating after meals, nails that split, a tiredness that sleep doesn't fix.

Digestion is a chain

Digestion works like a relay race, with each stage handing over to the next. If one runner stumbles, everything that follows is affected.

• The mind. Digestion begins before the first bite. The sight and smell of food, and simply feeling relaxed, prepare the stomach and release saliva. This is why eating on the run, or while stressed, so often ends in discomfort.
• The mouth. Chewing breaks food into smaller pieces and mixes it with saliva, which begins to digest starch.
• The stomach. Strong stomach acid breaks down protein, kills unwanted microbes, and frees minerals and vitamin B12 from food so they can be absorbed later.
• The pancreas and gallbladder. Enzymes from the pancreas digest protein, fat and starch. Bile from the liver and gallbladder breaks fat into tiny droplets, which we need to absorb vitamins A, D, E and K.
• The small intestine. Here, millions of tiny finger-like folds called villi absorb nutrients into the blood. Together, the lining of the gut has a surface area of around 30 square metres, about half the size of a badminton court.¹
• The large intestine. Gut bacteria ferment fibre, making short-chain fatty acids that feed the gut lining, as well as some B vitamins and vitamin K.

Where the chain can break

Low stomach acid

We often think of indigestion as too much acid, but many people, especially as they get older, have too little. Up to a third of people over 50 have a thinning of the stomach lining called atrophic gastritis, which reduces acid and makes it much harder to absorb vitamin B12 from food.² Long-term stress, the stomach bug H. pylori, and some medicines can also lower acid.

Long-term use of acid-reducing medicines (proton pump inhibitors, such as omeprazole) has been linked with low levels of vitamin B12³ and, less often, magnesium. These medicines are important for many people, so never stop or change them without speaking to your prescriber. But it may be worth asking whether your levels should be checked.

Sluggish bile and enzymes

If fat isn't digested well, you may notice pale, greasy or floating stools, nausea after rich meals, or discomfort under the right ribs. People who have had their gallbladder removed, or who have followed very low-fat diets for years, sometimes struggle with fat digestion and with absorbing the fat-soluble vitamins.

An inflamed gut lining

When the lining of the small intestine is inflamed or damaged, there's simply less surface to absorb nutrients. Coeliac disease is a clear example: it affects around 1 in 100 people in the UK, yet most are thought to be undiagnosed.⁴ Food sensitivities, an overgrowth of bacteria in the small intestine (SIBO), infections and long-term stress can all affect the gut lining too. (See The Master Regulator.)

You are not what you eat, but what you absorb.

From bloating to burn-out

When absorption falters, the body doesn't usually send an alarm. It quietly makes do, until reserves run low. These are some of the signs we look for:

• In the gut: bloating, burping, wind, a heavy feeling after eating, reflux, or seeing undigested food in your stools.
• In the nails, hair and skin: brittle or ridged nails, white spots on the nails, thinning hair, cracks at the corners of the mouth, a sore tongue, or slow-healing cuts. (See Skin Deep.)
• In the energy and mood: tiredness that doesn't lift, breathlessness on stairs, poor concentration, low mood and low stress tolerance.
• In the muscles and nerves: cramps, twitching eyelids, restless legs, or pins and needles.
• In the immune system: catching every cold going.

Three nutrients often sit at the heart of this kind of burn-out:

• Iron carries oxygen around the body. Iron deficiency is the most common nutrient deficiency in the world, and you don't need to be anaemic to feel its effects. In a trial of women with unexplained tiredness and low iron stores but normal blood counts, iron reduced fatigue by almost half.⁵
• Vitamin B12 is needed for energy, red blood cells and healthy nerves. Absorbing it depends on good stomach acid and a protein made in the stomach, so it is often the first nutrient to suffer when digestion weakens.
• Magnesium is involved in more than 300 processes in the body, including making energy. Stress drains magnesium, and low magnesium makes us more sensitive to stress, a vicious circle that researchers have described in detail.⁶

Helping your body absorb

How you eat

• Sit down and slow down. Take a few slow breaths before eating to switch on the body's "rest and digest" mode.
• Chew well. The stomach has no teeth. Aim to chew until food is soft and smooth.
• Leave gaps between meals. Constant grazing keeps digestion busy and gives the gut's natural "cleaning wave" no chance to sweep through.
• Eat your largest meal earlier in the day, when digestion tends to be strongest.

Clever food pairings

• Vitamin C with plant iron. Vitamin C can greatly increase how much iron we absorb from plant foods.⁷ Add peppers, parsley, tomatoes or a squeeze of lemon to lentils, beans and greens.
• Tea and coffee between meals, not with them. Tea can sharply reduce iron absorption from a meal.⁸
• Healthy fats with vegetables. Adding avocado to a salad helped people absorb several times more of the protective carotenoids from the vegetables.⁹
• Soak, sprout and ferment. Grains, beans, nuts and seeds contain phytates, which hold on to iron, zinc and calcium. Traditional soaking, sprouting, fermenting and sourdough baking reduce them.
• Black pepper with turmeric. A compound in black pepper increased how much curcumin, from turmeric, reached the blood by 2,000%.¹⁰

Herbs and foods that support digestion

• Bitters, such as rocket, dandelion and gentian, taken before meals, encourage stomach acid, bile and enzymes. (See Bitter Is Better.)
• Ginger helped the stomach empty more quickly in people with indigestion.¹¹ It is warming, and suits a "cold", slow digestion.
• Peppermint oil has been shown in trials to ease the pain and bloating of irritable bowel syndrome.¹² It is cooling, and may worsen reflux.
• Fennel, chamomile and cardamom are traditionally used to relieve wind and bloating.
• Soothing herbs such as marshmallow root, slippery elm and plantain coat and calm an irritated gut lining.
• Fermented foods such as sauerkraut, kefir and kimchi support healthy gut bacteria. (See The Quiet Fire.) Homemade versions hold many times more live bacteria than most shop-bought ones; try our sauerkraut, kefir and kimchi recipes.

In herbal medicine, a digestion that is cold, slow and heavy needs different herbs from one that is hot, sharp and acidic. (See The Architecture of Balance.) A qualified practitioner can help you choose the herbs that suit you, rather than self-prescribing.

At Rootwise, we always look at digestion first. There's little point in eating the finest food, or taking the best supplements, if the body can't take them in. Often, the most powerful change is simply learning to eat in a way that lets digestion do its work. Good digestion is also the root that feeds everything else: the energy to move, the minerals for strong bones, the building blocks for balanced hormones and a steady mood. (See Vital Force.)