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Symptoms and nutrients
For a symptom like tiredness, hair loss or muscle cramps, which nutrients get discussed, how strong the evidence really is, the foods richest in each, and when a symptom means "see a doctor" instead. Symptoms have many causes; this is not diagnostic.
General information only, not a diagnosis. A symptom is not proof of a deficiency — most symptoms here have many possible causes, and the common ones are rarely nutritional. Do not start a supplement to treat a symptom; the safe route is a blood test if one is warranted, and a doctor to interpret it. Use the red-flag list on each page, and see a clinician for anything that persists or worries you.
The honest framing before you read on
People search a symptom and a nutrient together hoping for a clean answer — this tiredness means that deficiency. Bodies do not work that way. A symptom is the end of a long list of possible causes, and for the symptoms on this list the common causes are usually sleep, stress, illness, medication or an underlying condition, not a missing nutrient.
A handful of deficiencies genuinely do produce some of these symptoms, and when they are present and corrected, people feel better. The mistake is running the logic backwards: "deficiency X can cause symptom Y" does not mean "I have symptom Y, therefore I am short of X." That backwards step is how people end up taking supplements they do not need — some of which cause harm in excess. Each page below rates how strong the evidence actually is, so you can tell the real links from the hopeful ones.
Pick a symptom
Tiredness and low energy
Tiredness is the most searched symptom on this list and the least specific. It is a normal response to poor sleep, stress and overwork, a feature of dozens of medical conditions, and occasionally the presenting sign of a nutrient deficiency that a blood test would find in minutes.
Hair loss and thinning
Hair shedding has a long list of causes, most of which are not nutritional. The commonest by a wide margin is genetic pattern hair loss, followed by telogen effluvium — a delayed shedding response to a stressor two or three months earlier.
Brittle, splitting or ridged nails
Nails split, peel and ridge for reasons that are mostly mechanical and environmental. Nutrition is in the conversation, but it is well down the list behind water, detergent, solvents and age.
Muscle cramps
Night cramps and exercise cramps are extremely common, and the nutritional explanations attached to them are among the least well supported on this whole page.
Low mood
Low mood is a symptom, not a diagnosis, and the distance between a low week and a depressive illness is a clinical judgement rather than something a checklist can make. This page covers only the nutritional part of a much larger conversation.
Poor concentration and brain fog
"Brain fog" is a description rather than a diagnosis, and it covers everything from a bad night's sleep to the aftermath of an infection to an untreated attention disorder.
Getting ill often
Catching several colds a winter is normal, particularly for adults living with young children. The nutrients associated with immune function are worth knowing about, and the marketing around them is far ahead of the evidence.
Bruising easily
Bruising more than you used to is worth taking to a doctor rather than to a supplement shelf, because the useful causes are medicines, blood counts and clotting rather than diet.
Cold hands and feet
Cold extremities are usually about circulation and how your blood vessels respond to temperature, rather than about what you have eaten.
Restless legs
Restless legs syndrome is one of the few entries on this page where a nutrient measurement is genuinely part of standard clinical assessment — and the nutrient is iron.
Dry skin
Dry skin is dominated by what happens to the outside of the skin — water, soap, heating, weather and time — with nutrition playing a much smaller role than the supplement market implies.
Slow-healing wounds
A wound that is not healing on schedule is a medical situation rather than a nutritional puzzle — but nutrition is one of the few things that genuinely modifies healing, which is why it belongs on this page with clear boundaries.
Frequently asked questions
Can a symptom tell me which nutrient I am short of?
No. Symptoms are not specific: tiredness, for example, has dozens of causes and most are not nutritional. At best a symptom is a prompt to ask whether a blood test is warranted — it is never proof of a deficiency.
Should I just take a supplement to be safe?
Usually not. Several nutrients — iron and fat-soluble vitamins in particular — cause harm in excess, and taking them without a confirmed deficiency has no benefit. The evidence that supplements fix these symptoms in people who are not deficient is mostly weak. A blood test first is the safer order.
Is this page going to diagnose me?
No. It explains what is commonly discussed and how good the evidence is, so you can have a better conversation with a clinician. It cannot and does not diagnose anything.
When should I actually see a doctor?
Every symptom page has a red-flag list. In general: anything that is severe, persistent, worsening, or comes with weight loss, fever or other warning signs deserves a professional opinion rather than a supplement.
Where do the food numbers come from?
The "richest foods" tables are computed from the USDA FoodData Central reference database, per 100 g — the same public data behind the nutrient toplists on this site. They show where a nutrient is found, not a recommendation to eat more of it.
Nutrient toplists · Blood test reference ranges · Calorie needs by life stage
Notice patterns before you jump to a cause
TempoLife logs sleep, food, activity and how you feel, so a persistent symptom has real context when you see a doctor — instead of a guess.