All About Kidney Health
The kidneys are often described as the body’s unsung heroes, two bean-shaped organs, each roughly the size of a fist, that perform critical functions 24 hours a day. Despite their modest appearance, the kidneys filter approximately 180 litres of blood daily, regulate fluid and electrolyte balance, manage acid–base homeostasis, and produce hormones essential for blood pressure control and red blood cell production (Koeppen & Stanton, 2018). As a nutritionist, I frequently encounter clients who are unaware of their kidneys’ workload until subtle symptoms emerge. This article explores the kidneys’ multifaceted roles, early indicators of suboptimal function, the profound influence of diet, lifestyle, and pharmaceuticals on renal wellbeing, and crucially, the bidirectional communication pathways linking the kidneys to the brain and other organ systems. These “axes” demonstrate the role of kidneys not only as filters, but as central nodes in whole-body homeostasis.
What Your Kidneys Actually Do All Day
Every minute, your kidneys filter blood through a million tiny sieves called nephrons. They decide what stays (water, glucose, sodium) and what goes out in urine (waste, extra salt, acids). They also:
Keep your blood pressure stable by releasing renin, a hormone that tightens blood vessels when needed (Sparks et al., 2014).
Make erythropoietin (EPO) to tell your bone marrow, “Make more red blood cells” (Blaine et al., 2015).
Turn vitamin D into its active form so your gut can absorb calcium for strong bones (Blaine et al., 2015).
When kidneys slow down, the ripple effects show up far beyond the bathroom (Levey & Coresh, 2012).
Early, Easy-to-Miss Clues Your Kidneys Need Attention
Chronic kidney disease (CKD) sneaks up on 1 in 10 adults worldwide and often stays silent until kidney function drops below 60% (Hill et al., 2016). Here are the subtle signs I teach my clients to watch for:
Always tired, even after a good night’s sleep – could be low red blood cells or waste building up in the blood (Stenvinkel et al., 2018).
Puffy eyes or ankles, especially first thing in the morning – a sign your kidneys aren’t clearing extra fluid (Levey et al., 2020).
Needing to wee 2+ times at night, foamy urine, or very pale urine – classic red flags for protein leak or poor concentrating ability (Webster et al., 2017).
Itchy, dry skin that won’t go away – often from minerals such as phosphate piling up (Shirazian et al., 2017).
Metallic taste or no appetite – waste products can dull your taste buds (McIntyre et al., 2019).
Catch these early with a simple blood test (eGFR) and urine test (albumin-to-creatinine ratio) (Levey et al., 2020).
Your Kidneys Talk with the Rest of Your Body
Think of your organs as teammates. When the kidneys struggle, they send stress signals; the other organs reply, sometimes helpfully, sometimes making things worse. Here’s how the conversations usually go, and what you can do to keep the chat positive.
Kidney ↔ Brain Chat
What they say to each other:
Kidneys send waste molecules (e.g., indoxyl sulphate) that can cross into the brain and cause inflammation (Bobot et al., 2020).
The brain responds with stress hormones and poor sleep signals, which raise blood pressure and can further damage the kidneys (DiBona, 2013).
What you notice: brain fog, trouble concentrating, feeling “off” even when you’re not sick. People with CKD have up to 65% higher risk of cognitive decline (Bugnicourt et al., 2013).
What you can do:
Eat more fibre (30 g/day) from oats, beans, and veg to trap waste in the gut before it reaches the brain (Yang et al., 2018).
Swap red meat for plant proteins a few times a week, less waste, happier brain (Ko et al., 2020).
Kidney ↔ Gut Chat
What they say:
Struggling kidneys let urea leak into the gut. Bad gut bacteria turn it into toxins (TMAO, p-cresyl sulphate) that travel back to the kidneys causing inflammation (Ramezani & Raj, 2014).
A healthy gut microbiome sends anti-inflammatory short-chain fatty acids to calm kidneys down (Yang et al., 2018).
What you notice: bloating, constipation, or just feeling “toxic.”
What you can do:
Add a daily fermented food (yoghurt, kefir, kimchi) and a prebiotic (cooled cooked potatoes, green bananas, leeks, asparagus, onions) (Yang et al., 2018).
Aim for 7–10 different plants on your plate each day—variety feeds the good bugs (Bach et al., 2019). I always ask my clients to “eat the rainbow”.
Kidney ↔ Heart Chat
What they say:
Kidneys retain fluid → heart pumps harder → high blood pressure → stiffer kidneys (Ronco et al., 2008).
A tired heart sends less blood to kidneys → kidneys panic and release more renin → even higher pressure (Ronco et al., 2008).
What you notice: swollen ankles, shortness of breath on stairs, or a racing heart at rest.
What you can do:
Keep sodium under 2,000 mg/day (avoid processed and ultra processed foods; flavour with herbs) (Mills et al., 2016).
Walk briskly 30 minutes most days, as this improves blood flow to both organs (Johansen & Painter, 2019).
Kidney ↔ Bone Chat
What they say:
Kidneys can’t activate vitamin D or clear phosphate → bones release calcium → weak bones + calcified arteries (Blaine et al., 2015).
What you notice: aching joints, easy fractures, or muscle cramps.
What you can do:
Choose plant proteins (lower phosphorus than processed meats) (Kalantar-Zadeh et al., 2010).
Get safe sun exposure or consider a vitamin D supplement if levels are low (through blood test, ask your GP) (Blaine et al., 2015).
Kidney ↔ Liver Chat
What they say:
Fatty liver → insulin resistance → inflamed kidneys (Bach et al., 2019).
Cirrhosis → low blood pressure to kidneys → kidneys shut down (hepatorenal syndrome) (Wong et al., 2019).
What you notice: yellow skin/eyes, abdominal swelling, or sudden kidney changes in liver patients.
What you can do:
Follow a Mediterranean-style diet: make sure you plate is half veg, quarter lean protein, quarter whole grains (Bach et al., 2019).
Limit alcohol to 1 standard drink/day (women) or 2 (men)—or none if liver is already stressed (Cheungpasitporn et al., 2015).
Everyday Choices to Keep Your Kidneys Happy
Nutrition:
Plate rule: 50% veggies (non-starchy), 25% lean/plant protein, 25% whole grains (Bach et al., 2019).
Sodium goal: <2,000 mg/day (read labels; rinse canned beans) (Mills et al., 2016).
Hydration: urine pale yellow; filtered plain water is best (Clark et al., 2016).
Fibre target: 30 g/day (oats at breakfast, beans at lunch, veggies at dinner) (Yang et al., 2018).
Movement:
150 minutes moderate activity/week (brisk walk, swim, cycle) plus two short strength sessions. Exercise lowers inflammation in every axis (Johansen & Painter, 2019).
Sleep & Stress:
7–9 hours quality sleep calms the kidney-brain sympathetic loop (McMullan et al., 2017). A 5-minute breathing break twice daily lowers blood pressure.
Medicines:
Avoid long-term NSAIDs (ibuprofen); use paracetamol (if necessary) or topical relief (Whelton, 2018) or try nutraceuticals for pain relief.
If on blood pressure meds (ACEi/ARB or SGLT2i), pair with low-potassium veg choices to avoid high potassium (Bakris et al., 2020; Heerspink et al., 2020).
Avoid PPIs as long term use can damage kidneys.
Review all meds with your pharmacist yearly, some quietly stress kidneys (Pryka, 2021).
Quick Action Plan for Clients
1.Book a kidney check: eGFR + urine ACR if over 45, diabetic, hypertensive, or family history (Levey et al., 2020).
2. Start a 3-day food diary: I’ll spot sodium, protein, and fibre patterns.
3.Pick one axis to support this week: e.g., add a daily fermented food for gut-kidney love.
4. Move 30 min most days: even a lunch walk counts (Johansen & Painter, 2019).
5. Medication check-in: bring pill bottles to your next appointment.
The Bottom Line
Your kidneys don’t work alone, think of them as the quiet coordinator in a lively group chat with your brain, gut, heart, bones, and liver. When the kidneys struggle, the messages turn stressful; when they thrive, the whole conversation stays calm and productive. If you want to check whether your kidneys are on track to extend your health span, book an appointment here.
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