Could Vitamin D Status and Dietary Fat Influence Anxiety?
Exploring the relationship between vitamin D, saturated fat, nutrition and mental wellbeing
Anxiety is influenced by many factors, including genetics, life experiences, sleep, stress, physical health, hormones and nutrition. While diet is not a substitute for appropriate psychological or medical care, growing research suggests that nutritional status and dietary patterns may be relevant to mental wellbeing.
Two areas that have attracted considerable interest are vitamin D status and dietary fat intake.
But does low vitamin D cause anxiety? And can eating too much saturated fat contribute to anxious feelings?
The evidence is more complex than a simple yes or no.
Vitamin D and the Brain
Vitamin D is traditionally associated with bone health and calcium metabolism, but vitamin D receptors are also found in tissues throughout the body, including the brain.
Vitamin D has been proposed to influence neurological function through several mechanisms, including regulation of inflammation, neurotrophic factors, neurotransmitter pathways and gene expression. These mechanisms have led researchers to investigate whether inadequate vitamin D status may be associated with depression, anxiety and other mental-health outcomes (Borges-Vieira & Cardoso, 2023; Laird et al., 2018).
Observational research has reported associations between lower vitamin D concentrations and poorer mental-health outcomes. For example, a systematic review examining vitamin D and mental health found evidence suggesting a relationship between vitamin D status and several psychological outcomes, although the results were not consistent enough to establish causation (Laird et al., 2018).
More recent research continues to show an association in some populations. A 2024 systematic review and meta-analysis examining women during pregnancy and the postnatal period found differences in vitamin D concentrations in relation to depressive symptoms, although evidence relating specifically to anxiety was much more limited (Centeno et al., 2024).
This distinction is important.
An association does not necessarily mean that vitamin D deficiency causes anxiety.
People experiencing anxiety may also have differences in lifestyle, diet, physical activity, sleep, lack of sun exposure or other health factors that influence vitamin D status.
Can Vitamin D Supplementation Reduce Anxiety?
This is where the research becomes particularly interesting.
If low vitamin D were directly causing anxiety, we would expect supplementation to consistently improve anxiety symptoms. However, clinical trials have produced mixed findings.
A randomised controlled trial involving people with low vitamin D levels and depressive and anxiety symptoms found that vitamin D supplementation was associated with an improvement in anxiety symptoms over six months (Zhu et al., 2020).
However, larger evidence reviews have been less conclusive.
A systematic review and dose-response meta-analysis of 31 randomised controlled trials involving more than 24,000 participants found that vitamin D3 supplementation improved depressive symptoms in some circumstances but did not produce a statistically significant overall effect on anxiety symptoms (Shab-Bidar et al., 2024).
Similarly, a systematic review of vitamin D supplementation and mental health in healthy adults concluded that the evidence for improving mental-health outcomes other than depression was not strong (Zhu et al., 2021).
Therefore, it may be more appropriate to think of vitamin D as one nutritional factor that may be relevant to some individuals, rather than a universal treatment for anxiety.
What About Saturated Fat?
Saturated fat is another area where nutrition and mental health research can be easily oversimplified.
Saturated fats are found naturally in foods such as butter, cream, cheese, fatty meats and coconut products, as well as in many processed foods.
It is important to recognise that not all foods containing saturated fat have the same nutritional profile.
For example, the effect of eating cheese as part of a whole-food diet may be very different from consuming large quantities of ultra-processed foods that contain saturated fat alongside refined carbohydrates, added sugars and excess calories.
Research investigating dietary patterns has found associations between higher-fat or Western-style dietary patterns and anxiety, but these studies cannot always separate the effects of saturated fat from the many other components of the diet (Sarris et al., 2021).
A large scoping review of nutrition and anxiety found that higher anxiety was associated in some studies with refined seed oils intake, inadequate protein and tryptophan intake, high sugar and refined carbohydrate consumption, and generally unhealthy dietary patterns. However, the authors highlighted that much of the evidence came from observational and animal studies and that more high-quality intervention research is needed (Sarris et al., 2021).
Saturated Fat Does Not Automatically Mean “Anxiety”
Interestingly, individual studies do not always support the idea that saturated fat directly increases anxiety.
In a randomised crossover study, healthy university students consumed diets differing in fatty-acid composition. The researchers found no significant differences in anxiety scores between the dietary conditions, including the high-saturated-fat condition (Kiecolt-Glaser et al., 2016).
Another small dietary intervention found that reducing total dietary fat did not necessarily improve mood. In fact, some measures of tension and anxiety declined in participants consuming the higher-fat diet (Wells et al., 1998).
These findings highlight why it is problematic to describe saturated fat as a direct cause of anxiety.
The bigger question may be:
What does the overall dietary pattern look like?
The Importance of the Overall Diet
A diet high in saturated fat may sometimes be part of a broader dietary pattern that is also high in ultra-processed foods, refined carbohydrates, added sugars and low in fibre, vegetables, fruit, legumes and omega-3-rich foods.
Research increasingly suggests that overall dietary quality may be more meaningful than focusing on one nutrient in isolation.
For example, a systematic review and meta-analysis published in 2026 found that greater adherence to the EAT-Lancet dietary pattern was associated with a lower risk of anxiety in observational studies (Fang et al., 2026).
Similarly, a 2026 meta-analysis found that unhealthy dietary patterns were associated with higher odds of anxiety symptoms, although substantial heterogeneity between studies means the findings should be interpreted cautiously (Gonabad et al., 2026).
This suggests that nutrition for mental wellbeing is unlikely to be about simply removing one food or nutrient.
Instead, it may be about improving the overall nutritional environment.
What Does This Mean for Vitamin D and Dietary Fat?
Rather than asking:
“Is vitamin D deficiency causing my anxiety?”
or:
“Is lack of intake of saturated fat causing my anxiety?”
a more useful question may be:
“Are my nutritional and lifestyle foundations supporting my mental wellbeing?”
This can include considering:
Vitamin D status
Overall dietary quality
Adequate protein and amino-acid intake
Omega-3 fatty-acid intake
Fibre and plant-food consumption
Intake of highly processed foods
Blood glucose regulation and meal patterns
Sleep quality
Stress
Physical activity
Alcohol and caffeine consumption
Individual health history
For some people, nutritional assessment or laboratory testing may provide useful additional information.
Vitamin D status, for example, can be assessed through a blood test measuring 25-hydroxyvitamin D [25(OH)D]. Testing should be considered in the context of the individual's circumstances rather than assuming that supplementation is necessary.
A Food-First Approach
Rather than eliminating all foods containing saturated fat, a balanced approach is generally more appropriate.
Consider building meals around:
Protein: fish, eggs, poultry, legumes, tofu, yoghurt and other minimally processed protein sources.
Colourful plants: vegetables, fruit, herbs and leafy greens provide fibre and a wide range of micronutrients and phytochemicals.
Healthy fats: extra-virgin olive oil, nuts, seeds, avocado and oily fish can provide predominantly unsaturated fats.
Whole-food carbohydrates: oats, whole grains, legumes and other minimally processed carbohydrate sources can provide fibre and important micronutrients.
Vitamin D sources: oily fish, eggs and fortified foods can contribute to vitamin D intake, although dietary intake alone may not always provide sufficient vitamin D depending on individual circumstances.
The goal is not necessarily to fear saturated fat or take large doses of vitamin D.
The goal is to create a nutritionally adequate, varied and sustainable diet that supports the whole person.
Vitamin D production occurs mainly in the skin, where UVB light converts a cholesterol-derived molecule into vitamin D₃. Body fat then acts as an important storage site for vitamin D.
How it works
When sunlight reaches your skin:
UVB sunlight → 7-dehydrocholesterol → previtamin D₃ → vitamin D₃
More specifically:
7-dehydrocholesterol is present in the epidermis (the outer layers of skin).
UVB radiation from sunlight converts it into previtamin D₃.
Heat causes previtamin D₃ to rearrange into vitamin D₃ (cholecalciferol).
Vitamin D₃ enters the bloodstream.
The liver converts it into 25-hydroxyvitamin D [25(OH)D], the main form measured in a blood test.
The kidneys and other tissues can convert it into the biologically active hormone 1,25-dihydroxyvitamin D (calcitriol).
Where does the “fat” come in?
Vitamin D is fat-soluble, so it has an affinity for fatty tissues.
After vitamin D₃ is produced in the skin, some can be transported into subcutaneous adipose tissue (the fat underneath the skin), where it can be stored.
This creates an interesting relationship between vitamin D and body fat:
Sunlight → skin production → bloodstream → adipose storage
Because vitamin D can become distributed into a larger amount of adipose tissue in people with higher body-fat mass, circulating vitamin D concentrations can sometimes be lower. This is one reason obesity is associated with a greater prevalence of low measured 25(OH)D concentrations. However, this doesn't necessarily mean the person is simply “deficient because they have more fat”; vitamin D metabolism is more complicated than that.
When Should You Investigate Further?
If anxiety is persistent, worsening or interfering with everyday life, it is important to seek appropriate professional support.
Nutrition can be one component of a broader approach, but anxiety has many possible causes and should not automatically be attributed to a nutritional deficiency.
A personalised nutritional assessment may be useful when someone wants to explore whether dietary patterns, nutrient intake or relevant biomarkers could be contributing to their overall wellbeing.
This is particularly important because testing and supplementation should be individualised.
The Takeaway
Vitamin D and dietary fat are both relevant to human health, but the relationship between these nutrients and anxiety is not straightforward.
Current evidence suggests that:
Low vitamin D status is associated with some mental-health outcomes, but this does not prove that vitamin D deficiency causes anxiety.
Vitamin D supplementation may benefit some individuals, but clinical trials have not consistently demonstrated an improvement in anxiety.
Evidence linking saturated-fat intake directly to anxiety is inconsistent.
Overall dietary patterns may be more important than focusing on a single nutrient.
A nutrient-dense, minimally processed diet provides a strong foundation for physical and mental wellbeing.
Persistent anxiety should be assessed comprehensively rather than attributed to nutrition alone.
Your mental wellbeing is influenced by more than one nutrient. Looking at the whole picture may provide a more useful path forward.
Interested in a personalised nutrition assessment?
If you're experiencing anxiety, low mood, brain fog, fatigue or other concerns and would like to explore the nutritional factors that may be relevant to you, a personalised naturopathic nutrition consultation can help identify areas worth investigating.
References
Borges-Vieira, J. G., & Cardoso, C. K. S. (2023). Efficacy of B-vitamins and vitamin D therapy in improving depressive and anxiety disorders: A systematic review of randomized controlled trials. Nutritional Neuroscience, 26(3), 187–207. https://doi.org/10.1080/1028415X.2022.2031494
Centeno, L. O. L., Fernandez, M. D. S., Muniz, F. W. M. G., Longoni, A., & de Assis, A. M. (2024). Is serum vitamin D associated with depression or anxiety in ante- and postnatal adult women? A systematic review with meta-analysis. Nutrients, 16(21), 3648. https://doi.org/10.3390/nu16213648
Fang, K.-H., et al. (2026). Adherence to the EAT-Lancet diet and its association with depression and anxiety: A systematic review and meta-analysis of observational studies. Nutrients, 18(4), 684. https://doi.org/10.3390/nu18040684
Kiecolt-Glaser, J. K., et al. (2016). Neurobehavioral effects of consuming dietary fatty acids. Journal of Clinical Lipidology. https://pubmed.ncbi.nlm.nih.gov/27412317/
Laird, E., et al. (2018). Vitamin D and mental health: A systematic review and meta-analysis. Journal of Affective Disorders.
Sarris, J., et al. (2021). Diet and anxiety: A scoping review. Nutrients, 13(12), 4416. https://doi.org/10.3390/nu13124416
Shab-Bidar, S., et al. (2024). The effect of vitamin D supplementation on depression: A systematic review and dose-response meta-analysis of randomized controlled trials. Psychological Medicine. https://doi.org/10.1017/S0033291724001697
Taylor, Z. B., Stevenson, R. J., Ehrenfeld, L., & Francis, H. M. (2021). The impact of saturated fat, added sugar and their combination on human hippocampal integrity and function: A systematic review and meta-analysis. Neuroscience & Biobehavioral Reviews.
Wells, A. S., Read, N. W., Laugharne, J. D. E., & Ahluwalia, N. S. (1998). Alterations in mood after changing to a low-fat diet. British Journal of Nutrition, 79(1), 23–30. https://doi.org/10.1079/BJN19980005
Zhu, C., et al. (2020). Vitamin D supplementation improves anxiety but not depression symptoms in patients with vitamin D deficiency. Brain and Behavior, 10(11), e01884. https://doi.org/10.1002/brb3.1760
Zhu, J., et al. (2021). Association between vitamin D supplementation and mental health in healthy adults: A systematic review. Nutrients.
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