Mood

Food for SAD.

SAD is a seasonal mood disorder with a specific biology. Vitamin D deficiency, reduced serotonin synthesis, and a real carbohydrate craving drive most of the winter pattern — and all of them have dietary answers.

Affects approximately 5% of adults in the US; more common at higher latitudes.

The biology

Seasonal Affective Disorder is depression with a seasonal pattern, typically beginning in fall and remitting in spring. The primary driver is reduced light exposure, which affects melatonin regulation, serotonin synthesis, and vitamin D levels. The circadian rhythm is disrupted; the serotonin-to-melatonin conversion goes out of balance; and vitamin D, which requires sunlight synthesis, drops to levels that are independently associated with depressive symptoms.

There is also a specific SAD-related biology around carbohydrate craving. SAD sufferers often report intense carbohydrate cravings in winter. This appears to be a serotonin-driven phenomenon: reduced winter serotonin creates a biologically mediated drive toward carbohydrate consumption, which temporarily increases tryptophan availability and raises serotonin. The carbohydrate craving is a symptom, not a character flaw. The dietary strategy is to satisfy it intelligently: complex carbohydrates rather than refined, tryptophan-forward proteins alongside the carbohydrates.

Key nutrients

Vitamin D — Moderate-Strong evidence. The most direct dietary lever for SAD. Deficiency at baseline is extremely common in winter at northern latitudes. Target 25-OH-D above 50 ng/mL; 2000–4000 IU/day supplementation through winter is often necessary. Dietary D from salmon, eggs, and fortified foods supplements this but is usually insufficient alone in winter.

Tryptophan — Moderate evidence. Precursor to serotonin. Evening tryptophan-forward meals with moderate carbohydrate improve serotonin availability. Turkey, salmon, eggs, pumpkin seeds, oats.

Omega-3 fatty acids — Moderate evidence. General mood support, especially EPA for mood regulation. Northern traditional diets high in fatty fish show lower rates of SAD — a correlation with biological plausibility.

Foods to prioritize

Fatty fish (salmon, mackerel, herring, sardines) — vitamin D + omega-3s in one food. Eating these 3–4x/week is particularly important in winter.

Eggs (whole, with yolk) — vitamin D, B12, tryptophan, choline. Daily in winter.

Tryptophan-forward dinners: turkey, salmon, eggs, or lentils + moderate carbohydrate (sweet potato, brown rice, oats). The carbohydrate improves tryptophan crossing the blood-brain barrier.

Fortified dairy or plant milks — vitamin D fortified milk is a practical D source when sunlight is scarce.

Mushrooms exposed to UV light — a dietary vitamin D source. Gills-up in sunlight for 15–20 minutes before cooking significantly increases vitamin D content.

Dark chocolate (70%+) — the SAD winter craving is real. Dark chocolate satisfies it with polyphenols and magnesium, not empty calories.

Foods to be mindful of

Refined carbohydrates — the winter carbohydrate craving often drives toward refined carbs (bread, pasta, pastries). Satisfying the craving with complex carbohydrates (oats, sweet potato, brown rice, legumes) gives the same serotonin-boost mechanism without the blood sugar crash.

Alcohol — common self-medication in winter. Directly suppresses serotonin and disrupts sleep, amplifying the SAD pattern.

Timing and patterns

Vitamin D supplementation from October through March at northern latitudes. Start testing levels in fall. Don't wait for symptoms.

Tryptophan-forward dinner protocol. A medium-glycemic carbohydrate with a tryptophan-rich protein in the evening specifically improves serotonin production overnight and into the next day. This is not general nutrition advice — it's SAD-specific meal architecture.

Morning eating to anchor circadian rhythm. SAD involves circadian disruption. Consistent breakfast timing, ideally with morning light, is part of the treatment.

Sample meal plan

Day 1

Breakfast: Scrambled eggs with smoked salmon, slice of whole-grain toast (near a window if possible)
Lunch: Fortified yogurt with berries and hemp seeds
Dinner: Roasted salmon with sweet potato mash and steamed broccoli
Snack: Dark chocolate + a few walnuts

Day 2

Breakfast: Oats with banana, pumpkin seeds, and a boiled egg on the side
Lunch: Turkey and avocado wrap with leafy greens
Dinner: Chicken thighs with roasted root vegetables and brown rice
Snack: Warm golden milk (turmeric, ginger, cinnamon, fortified oat milk)

Day 3

Breakfast: Vitamin D-fortified milk with granola and berries
Lunch: Lentil soup with whole-grain bread
Dinner: Mackerel with quinoa and roasted kale
Snack: Tart cherry yogurt before bed

Evidence strength

Moderate

How Beckie adjusts

Beckie introduces the SAD vitamin D protocol proactively in fall for users who have identified SAD as a pattern or who live at northern latitudes (above 40°N). She doesn't wait for symptoms to start.

She validates the winter carbohydrate craving without moralizing about it — she explains the biology and redirects toward complex carbohydrate choices rather than elimination.

She checks vitamin D supplementation status and encourages users to get tested if they haven't.

Open Simmerstate

Important

Light therapy (a 10,000 lux light box for 20–30 minutes each morning) is the first-line treatment for SAD and is highly effective. If your seasonal depression is significantly impairing your functioning, please speak with your doctor or psychiatrist. Medication (SSRIs) is also effective for moderate-to-severe SAD. Dietary support is a meaningful adjunct to light therapy and medication, not a replacement.

When food isn’t enough

If dietary and lifestyle changes — including vitamin D supplementation and morning light — aren't producing meaningful improvement by November or December, please speak with your doctor. Light therapy and SSRIs are effective, well-tolerated, and available. Don't white-knuckle an entire winter when effective treatments exist.

Beckie builds your meal plan around this.

Personalized to your life, your schedule, your kitchen.

Open Simmerstate