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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.
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.
Three nutrients dominate the popular discussion of mood: vitamin D, omega-3 fats, and the B vitamins involved in one-carbon metabolism, principally folate and B12. All three have a plausible biological story, and all three have been tested in randomised trials, which is the useful part.
Vitamin D is the one people are most confident about and the evidence is the least supportive. Observational studies reliably find that people with low vitamin D have more depressive symptoms — and also less time outdoors, less activity, more illness and less daylight, all of which independently affect mood. Large randomised trials of supplementation in generally healthy adults have not shown a meaningful effect on depression. That is close to the cleanest test the question has had.
Omega-3 has a more mixed record. Some trials of EPA-predominant preparations as an add-on to conventional treatment for depression have been positive, others have not, and the effect sizes in meta-analyses move noticeably depending on which studies are included. It would be fair to call this unresolved rather than either established or debunked, and it is a decision to make with a clinician rather than in a supplement aisle.
Folate and B12 are the ones with the clearest deficiency link: both deficiencies can present with mood and cognitive symptoms, and both are found with a blood test. Correcting a real deficiency is treatment. Adding them to someone who is replete is not.
The thing worth saying loudest is that none of this is a substitute for treatment. Depression is common, it is treatable, and treatment works better the earlier it starts. If low mood is persistent, if it is affecting how you function, or if you have any thought of harming yourself, that is a reason to contact a doctor or an urgent helpline today rather than to read further.
Nutrients commonly discussed for low mood
Each nutrient below is rated for how strong the evidence is that it relates to this symptom. "Relevant only if you are deficient" means it can matter when your level is genuinely low, but topping it up when it is not low does nothing.
Vitamin D Mixed evidence
Strongly associated with mood in observational data, and unimpressive in large randomised trials of supplementation in generally healthy adults. The association is real; the causal direction is doubtful.
| Everyday food | Vitamin D per 100 g |
|---|---|
| Cod liver fish oil | 250 µg |
| Maitake mushrooms, raw | 28.1 µg |
| Greenland halibut, raw | 27.4 µg |
| Mackerel, salted | 25.2 µg |
| Carp, raw | 24.7 µg |
| Eel, raw | 23.3 µg |
Full ranking: foods highest in vitamin d.
Omega-3 Mixed evidence
Trials as an add-on to conventional treatment have produced genuinely mixed results, with effect estimates sensitive to which studies are pooled. Unresolved rather than settled, and a decision for a clinician.
| Everyday food | Omega-3 per 100 g |
|---|---|
| Salmon fish oil | 18.2 g |
| Chia seeds | 17.8 g |
| Cod liver fish oil | 11 g |
| Sardine fish oil | 10.7 g |
| Canola oil | 9.1 g |
| Hulled hemp seed | 8.7 g |
Folate Relevant only if you are deficient
Deficiency can present with mood and cognitive symptoms. Found on a blood test, and treated as a deficiency rather than as a mood intervention.
| Everyday food | Folate per 100 g |
|---|---|
| Yeast extract spread | 3786 µg |
| Active dry yeast | 2340 µg |
| Quaker Cap'n Crunch With Crunchberries | 1630 µg |
| Quaker Halloween Crunch | 1615 µg |
| Quaker Cap'n Crunch | 1555 µg |
| Quaker Peanut Butter Crunch | 1554 µg |
Vitamin B12 Relevant only if you are deficient
Same story as folate, and more likely with age, a vegan diet or certain long-term medicines. Correcting a real deficiency is worthwhile; adding it to a replete person is not.
| Everyday food | Vitamin B12 per 100 g |
|---|---|
| Clam, cooked | 98.9 µg |
| Beef liver, cooked | 96 µg |
| Lamb liver, fried | 85.7 µg |
| Veal liver, braised | 84.6 µg |
| Beef liver, pan-fried | 83.1 µg |
| Lamb kidneys, braised | 78.9 µg |
Full ranking: foods highest in vitamin b12.
Iron Relevant only if you are deficient
Iron deficiency produces fatigue and poor concentration, which are easily read as low mood. Worth measuring, particularly in menstruating women.
| Everyday food | Iron per 100 g |
|---|---|
| Canadian cultivated emi-tsunomata seaweed, dry | 66.4 mg |
| Beef spleen, raw | 44.5 mg |
| Lamb spleen, raw | 41.9 mg |
| Beef spleen, cooked | 39.4 mg |
| Lamb spleen, braised | 38.7 mg |
| Hershey's European Style Cocoa | 36 mg |
Full ranking: foods highest in iron.
Source: Foods richest in each nutrient: USDA FoodData Central SR Legacy (public domain), per 100 g · checked 2026-09-02
Causes that are usually more likely
Before a nutrient, these are the explanations a clinician would normally consider first for low mood:
- Depression and anxiety disorders
- Poor or insufficient sleep, and shift work
- Bereavement, relationship or financial stress
- Thyroid disease
- Alcohol and other substances
- Chronic pain and long-term illness
- Some medicines
- Seasonal light change, particularly at northern latitudes
When to see a doctor
Treat these as reasons to seek a professional opinion rather than to self-treat:
- Any thought of harming yourself or ending your life — contact a doctor or an urgent helpline today
- Low mood most of the day, most days, for two weeks or more
- Losing interest in things you normally enjoy
- Being unable to function at work, at home or with family
- Marked weight or appetite change alongside the mood change
- Feeling unusually agitated, or unusually slowed down
This list is not exhaustive, and a symptom that is severe, persistent or getting worse always deserves a professional opinion. If you feel very unwell, seek urgent care rather than reading further.
Frequently asked questions
Will vitamin D lift my mood?
Large randomised trials in generally healthy adults have not shown that it does. Low vitamin D is associated with low mood, but the association appears to run through shared causes such as being indoors and inactive.
Can nutrition replace treatment for depression?
No. Depression is treatable and treatment works better the earlier it starts. Nutrition sits alongside it, never instead of it.
Does this symptom mean I have a deficiency?
No. Low mood has many possible causes and most are not nutritional. A nutrient link is worth checking with a blood test only when other clues point that way — it is never established by the symptom alone.
Other symptoms
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.
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.
All symptoms · Nutrient toplists · Blood test reference ranges
Give a persistent symptom real context
TempoLife tracks sleep, food, activity and mood over time, so when you do see a doctor you bring a record instead of a guess.