Don’t Let Seasonal Affective Disorder (SAD) Get You Down: 10 Nutrients to Support You Through the Dark Days
As the days grow shorter and sunlight becomes scarcer, many people find themselves experiencing symptoms of Seasonal Affective Disorder (SAD). This mood disorder is commonly linked to the lack of natural sunlight, which disrupts our circadian rhythm, hormone balance, and vitamin D synthesis. From a functional nutrition standpoint, a root cause approach to managing SAD goes beyond just addressing the symptoms; it looks at underlying nutritional imbalances and deficiencies that may exacerbate mood and energy disturbances during these darker months. Here, we’ll explore key nutrients that can support brain health, boost mood, and help combat SAD—and the foods that provide them. I’ll also add a list of functional labs to recommend to your healthcare provider if you feel you need a deeper dive in to nutrition and your mood!
1. Vitamin D
Vitamin D plays a crucial role in mood regulation, with receptors found throughout the brain. Studies show that low levels of vitamin D can contribute to depressive symptoms, including those seen in SAD. Vitamin D deficiency is fairly common, impacting about 35-40% of Americans. It is more common in those who live in northern regions and those with darker skin, as it takes longer for people with higher melanin to synthesize vitamin D from the sun. However anyone who is not getting at least 30 minutes of sun exposure daily can be at risk for deficiency.
Foods to Support: While sunlight exposure is the most effective way to boost vitamin D, certain foods can help increase levels as well. Look for fatty fish like salmon, mackerel, and sardines, as well as fortified foods such as orange juice, milk, and plant-based milk alternatives. Mushrooms exposed to UV light are another good plant-based option. As a registered dietitian, this is one nutrient I often recommend my clients to supplement outside of food sources, as it is found in smaller amounts in food and hard to get when our daylight is shorter and the sun is farther away from the Earth.
2. Iron
Iron deficiency can lead to fatigue, brain fog, and mood disturbances, which can worsen SAD symptoms. Iron is essential for oxygen transportation in the body and is a key player in energy production and neurotransmitter synthesis. The World Health Organization (WHO) estimates about 30% of the world population suffers from iron deficiency anemia, with even more experiencing non-anemic iron deficiency. While it is important to get plenty of iron as part of your daily dietary intake, iron deficiency can also be caused by poor absorption of iron due to gut inflammation.
Foods to Support: Lean meats like beef, turkey, and chicken, grass-fed beef liver and eggs are rich sources of heme iron (which is more readily absorbed by the body). For plant-based (non-heme) sources, try lentils, chickpeas, beans, spinach, and pumpkin seeds. Consider pairing with vitamin C-rich foods like bell peppers or citrus fruits to boost absorption.
3. Vitamin B12
Vitamin B12 is essential for brain health, energy production, and mood regulation, as it supports the production of neurotransmitters that regulate emotions— serotonin and dopamine. Low levels of B12 can lead to depressive symptoms, fatigue, and decreased cognitive function, associated with SAD. Individuals may struggle from vitamin B12 deficiency due to imbalances in production of stomach acid, which contains intrinsic factor (IF), an essential glycoprotein responsible for the absorption of B12, small intestinal bacterial overgrowth (SIBO), or inflammation of the lining of the small intestine due to diseases like Celiac or Chron’s Disease. Some medications like proton pump inhibitors (PPIs), H2 Blockers, and metformin can interfere with B12 absorption. Speak with your dietitian or healthcare provider if you suspect one of these conditions or medications may be impacting your B12 levels.
Foods to Support: Animal products are the best sources of B12, including beef, chicken, fish, eggs, and dairy products. For vegetarians and vegans, B12-fortified plant milks, cereals, and nutritional yeast are helpful options, though supplementation is often necessary. Check with your dietitian or healthcare provider to see if you may benefit from supplementation.
4. Folate
Folate, or vitamin B9, works closely with B12 in neurotransmitter synthesis. It helps metabolize homocysteine, an amino acid that, in high levels, is associated with a higher risk of mood disorders. Many things can contribute to inadequate folate, like increased needs during pregnancy, certain medications, and inflammation in the gut. One thing to consider is some individuals, an estimated 1/3 of the population, have a mutation in the MTHFR (methylenetetrahydrofolate reductase) gene, affecting the conversion of folate into its active form, which can contribute to deficiency.
Foods to Support: Folate is found in leafy greens (spinach, collard greens, kale, turnip greens), legumes (beans, peas, lentils), avocados, and asparagus. Whole grains and fortified cereals can also be helpful sources, especially for those with higher needs.
5. Zinc
Zinc is vital for immune health and brain function, and low levels have been linked to depressive symptoms. It’s also important for maintaining mood and energy levels.
Foods to Support: Oysters are the richest source of zinc (a personal favorite of mine, with horseradish— yum!), but it’s also found in beef, pork, poultry, beans, nuts (cashews, almonds), whole grains, and dairy products. Pumpkin seeds are another great plant-based source of zinc.
6. Copper
Copper works synergistically with zinc and iron in the body and is necessary for the formation of neurotransmitters that regulate mood. While deficiency is rare, imbalances between copper with zinc do happen, and an imbalance can lead to mood-related issues.
Foods to Support: Copper can be found in shellfish, grass fed beef or lamb liver, nuts (especially cashews), seeds, dark chocolate, and whole grains. Incorporating these foods can help copper work synergistically with zinc, without overwhelming the balance. Always speak to your dietitian or healthcare provider before supplementing copper.
7. Magnesium
Magnesium is often referred to as the “relaxation mineral” because of its role in nervous system health, helping to reduce symptoms of anxiety, stress, depression and muscle tension. It also plays a role in melatonin regulation, a hormone that influences sleep cycles—key for managing SAD.
Foods to Support: Dark leafy greens, nuts (especially almonds and cashews), seeds, legumes, and whole grains are excellent sources of magnesium. Dark chocolate (with at least 70% cocoa) is another mood-boosting, and delicious, choice (there’s a reason we crave this around our menstrual cycle— but thats for another blog post!)
8. Tyrosine
Tyrosine is an amino acid involved in the production of dopamine, a neurotransmitter that plays a key role in motivation, pleasure, and focus—all of which can be depleted in those experiencing SAD. Tyrosine-rich foods support the brain’s ability to produce dopamine naturally.
Foods to Support: Good sources include turkey, chicken, dairy products, soy products, almonds, bananas, and avocados. Incorporating these foods into meals can support steady dopamine production and mental focus.
9. Tryptophan
Tryptophan is an amino acid that is a precursor to serotonin, a neurotransmitter that regulates mood, sleep, and appetite. Adequate serotonin levels are essential for feeling calm and balanced, and low serotonin is commonly linked to depressive symptoms.
Foods to Support: Tryptophan is found in turkey, chicken, milk, cheese, nuts, and seeds. Tryptophan-rich plant foods include tofu, soybeans, pumpkin seeds (are you seeing a theme here??), and bananas. Pairing tryptophan sources with complex carbohydrates (think turkey and mashed potatoes or peri peri chicken with jollof rice) can enhance its absorption in the brain, boosting serotonin levels.
10. Fiber
Fiber plays a surprising yet powerful role in supporting mood, primarily through its effects on gut health, inflammation, and blood sugar regulation. Establishing a healthy gut microbiome through eating a fiber-rich diet contributes to the body’s ability to produce serotonin— ~ 90% of which is created in the gut! The Institute of Medicine and the Academy of Nutrition and Dietetics recommend women get at least 25 grams and men get a least 38 grams of fiber each day. However, the average American gets less than 15 grams per day!
Foods to Support: Whole, plant based foods like vegetables, fruits, legumes, seeds and whole grains are the best ways to incorporate fiber in to your diet. If you’re having a tough time eating enough fiber, you can try adding a combination of these foods to a smoothie or adding a fiber supplement like psyllium husk or inulin in to your beverage of choice.
Labs to Look at for SAD:
While you can start by evaluating how well you’re doing at getting the 10 supportive nutrients listed above by looking at your daily dietary intake, it’s important to note that sometimes symptoms experienced with SAD may also be a sign of another underlying condition or imbalance. If you’re curious how your body is doing at supporting your energy and mood, here are some of the labs I may suggest starting with:
Vitamin D
Iron + Ferritin
CBC
CMP
Homocysteine
Vitamin B12
Folate/Folic Acid
Copper
Zinc
Magnesium RBC
Thyroid panel with thyroid antibodies
Fasting Blood Glucose
Fasting Insulin
HOMA-IR
hs-CRP
To schedule a nutrition assessment with functional lab interpretation click here.
Weaving it All Together
A root cause approach to managing Seasonal Affective Disorder focuses on identifying and addressing potential nutrient deficiencies that may underlie mood-related symptoms. Incorporating whole and fortified foods rich in these key nutrients can create a strong nutritional foundation that supports brain health and emotional well-being. Here are a few practical tips for integrating these nutrients into your diet this winter season:
Prioritize Variety: Include a range of foods to ensure you’re getting a full spectrum of these nutrients. Aim for a balance of protein, healthy fats, and complex carbohydrates with each meal to stabilize energy and mood.
Boost Absorption: For minerals like iron and zinc, consider pairing plant sources with vitamin C to enhance absorption. Similarly, combining tryptophan-rich foods with complex carbs can aid serotonin production. Speak with your dietitian or healthcare provider if you suspect something may be inhibiting your ability to absorb certain nutrients. For an in-depth nutrition assessment with me, click here.
Consider Seasonal Supplements: If food alone isn’t meeting your needs, particularly for nutrients like vitamin D and B12, speak with your dietitian or healthcare provider about possible supplementation.
Taking a holistic, root-cause approach to SAD can make a profound difference in how you experience the winter months. While the purpose of this article is to look at the way nutrition plays a role in supporting SAD, it is also important to consider the other possible root-causes in your life like sleep, exercise/movement, relationships/community, other illnesses/conditions, environmental stressors and access to medical care. By nourishing your body with the right nutrients, you can set yourself up with greater support for optimal brain health and resilience, making the winter season feel a bit lighter while we wait for the light in the sky to return!
