Get your Brain Health Score (in 4 mins) Take the quiz

Rest of World

Vitamin D3 Benefits and Dosage

Vitamin D3, aka the “sunshine vitamin" can lift your mood and support immunity, as well as build strong bones and teeth.

ingredients 05 vitamin-D3 illustration
Sophie Medlin
Sophie Medlin
Head of Nutritional Research
April 14, 2020
8 min read

Vitamin D3, aka the “sunshine vitamin" can lift your mood and support immunity, as well as build strong bones and teeth. 

Vitamin D3 benefits

A fat-soluble vitamin that is important for:

  • Preventing cognitive decline

  • Regulating the production of calcium and phosphate in bones

  • Bone growth and remodelling

  • Reducing inflammation

  • Regulating cell growth

  • Enhancing neuromuscular function

  • Supporting immune function

  • Helping with glucose metabolism

How much vitamin D3 should I take?

The nutrient reference value (NRV—formerly RDA) is 10 mcg/day (or 400 IU).

1 billion people in the world are suffering from vitamin D deficiency. 

Researchers have now concluded that we need more vitamin D than is currently recommended for overall health and to prevent chronic diseases. 

Granted, your body makes vitamin D when those golden rays of sunshine fall on your skin, and also when you eat certain foods, but it’s not always enough. Moreover, coronavirus (SARS-CoV-2) has forced people to spend more time indoors, so Public Health England (PHE) has asked everyone (not just at-risk groups) to consider taking a daily vitamin D supplement.  

In every Smart Supplement dose

45 mcg (1800 IU) – that’s the equivalent of 40 eggs or 26 tablespoons of fortified margarine*

(*Ain’t nobody got time for that)

Benefits of vitamin D3 on the brain

Vitamin D3 is a nutritional superhero that helps to prevent cognitive decline, as well as playing an important role in immune function. It’s involved in many brain processes including neuro-immunomodulation (a fancy way of saying that it regulates the production of compounds in your brain that can boost your immune system). 

Receptors for vitamin D3 (and the enzyme that converts it into its active form) are present in the parts of your brain that control cognitive function as you age. When vitamin D3 attaches to these receptors, it can inhibit an enzyme involved in the development of Alzheimer’s and Parkinson’s disease. In one study, vitamin D concentrations were lower in patients with dementia than those without. 

In two other studies, people with vitamin D deficiency had higher rates of mood disorders, depression, and low mood. Although vitamin D is not recommended as a first-line treatment for depression, it may be beneficial in combination with therapy. 

One study showed that vitamin D supplementation may also help with decreasing the risks of developing multiple sclerosis (MS) by influencing how the immune system works. However, more research is needed to find out how much vitamin D supplementation is necessary to decrease MS risks.

Benefits of vitamin D3 on the body

Vitamin D3 does so much more than give you strong bones and teeth. Here are some evidence-based benefits of vitamin D3 on the body:

  • Promotes healthy bones, teeth, and muscles. 

  • Enhances the body’s immune system.

  • Decreases the multiplication of cancerous cells, and prevents the formation of new blood vessels and inflammation.

  • Protects the heart by reducing inflammation (low vitamin D3 has been linked to a higher risk of heart disease).

  • Regulates sodium concentrations through the renin-angiotensin system, which decreases the risk of hypertension.

  • Low vitamin D has been linked to obesity, type 2 diabetes, depression, auto-immune diseases, influenza, bacterial vaginosis, and age-related macular degeneration in women.

Why vitamin D is important for the ageing population

As you get older, the cells in your skin make less vitamin D from sunlight (cutaneous synthesis). Also, you may begin to spend less time outdoors and eat less of foods that are fortified with vitamin D.

This means that ageing adults are at risk of vitamin D deficiency. It also means that vitamin D may also influence some age-related medical conditions. It’s important that older adults aged 60 years and over consider taking a vitamin D supplement

Difference between vitamin D and D3

Vitamin D comes in two forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Vitamin D3 is the biologically-active form and is the more powerful of the two, increasing blood levels of vitamin D twice as much as D2. Vitamin D is the form most commonly found in fortified food products, while vitamin D3 mainly comes from animal sources such as fish oil and liver.

Vitamin D3 deficiency symptoms

Since 35% of total vitamin D intake from food is from meat and meat products (including fish), vegetarians need to get creative with supplementing their diet with vitamin D3. People who can’t tolerate or consume milk and eggs are also at higher risk of vitamin D3 deficiency. 

Insufficient amounts of D3 can prevent normal bone development and bone growth. It can also cause mood disorders, depression, and low mood.

Signs of Vitamin D3 deficiency include:

  • Fatigue

  • Bone pain

  • Muscle weakness, muscle aches, or muscle cramps

  • Mood changes, for example, depression

Diseases from prolonged vitamin D deficiency:

  • Rickets—bone tissues do not harden, which can cause soft bones and skeletal deformities in children

  • Osteopenia—bone tissues are weaker than normal, but not to the point of breaking easily

  • Osteoporosis—bone tissues are weak and brittle, increasing your risk of falls and fractures

  • Osteomalacia—weak and soft bones in adults

  • Muscle weakness—difficulty standing and walking in children; increased loss of balance and more frequent falls in the elderly

Vitamin D3 Foods

Most vitamin D3 comes from exposure to sunlight. However, eating the following foods also provides the body with some vitamin D3.

  • Salmon

  • Trout

  • Tuna

  • Swordfish

  • Sturgeon

  • Cod liver oil

  • Meat and meat products

  • Fortified milk and milk products

  • Fortified cereal and cereal products – about 13-20% of the total dietary intake of vitamin D in the UK population comes from these products

  • Fortified orange juice

  • Mushrooms

  • Eggs, hard-boiled

Vitamin D3 side effects

Too much vitamin D3 (more than 100 mcg/day) from supplements over time can be toxic. Since vitamin D3 helps with calcium absorption, too much of it can lead to excess calcium (hypercalcemia). 

Excess calcium can cause weak bones, muscle weakness, kidney stones, heart problems, or changes in how your brain works (for example, confusion, moodiness, or fatigue).

Don’t worry about vitamin D3 overdose from sunlight. Our body is brilliant at regulating the amount of vitamin D you get from the sun, so there’s no risk of ending up with too much.

Unless you consume your vitamins in conjunction with a fat, your body can’t absorb them. This is why we wrap vitamin D3 (and other fat-soluble vitamins like E and A) in omega 3 extracted from algae oil to make sure that your body can absorb it.  

Heights Smart Supplement bottle with blueberries, sugar snap and seeds
Heights Smart Supplement with blueberries and a snap pea
Our formula

The Smart Supplement

4.7/5 on Trustpilot
Find out why the Smart Supplement is the highest rated in the world, and how it helps to keep you feeling better, every day.
Find out more


  • Trang, H. M., Cole, D. E., Rubin, L. A., Pierratos, A., Siu, S., & Vieth, R. (1998). Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. The American journal of clinical nutrition, 68(4), 854-858.
  • Allan, G. M., Cranston, L., Lindblad, A., McCormack, J., Kolber, M. R., Garrison, S., & Korownyk, C. (2016). Vitamin D: a narrative review examining the evidence for ten beliefs. Journal of general internal medicine, 31(7), 780-791.
  • Vellekkatt, F., & Menon, V. (2019). Efficacy of vitamin D supplementation in major depression: A meta-analysis of randomized controlled trials. Journal of postgraduate medicine, 65(2), 74.
  • National Institutes of Health. (2014). Office of Dietary Supplements, Vitamin D Fact Sheet for Health Professionals.
  • Vaziri, F., Nasiri, S., Tavana, Z., Dabbaghmanesh, M. H., Sharif, F., & Jafari, P. (2016). A randomized controlled trial of vitamin D supplementation on perinatal depression: in Iranian pregnant mothers. BMC pregnancy and childbirth, 16(1), 1-12.
  • 2015-2020 Dietary Guidelines | Accessed January 21, 2021.
  • SACN vitamin D and health report. GOV.UK. Accessed January 21, 2021.
  • Statement from PHE and NICE on vitamin D supplementation during winter. GOV.UK. Accessed January 21, 2021.
  • Meehan M, Penckofer S. The Role of Vitamin D in the Aging Adult. J Aging Gerontol. 2014;2(2):60-71. doi:10.12974/2309-6128.2014.02.02.1
  • Penckofer S, Kouba J, Byrn M, Ferrans CE. Vitamin D and Depression: Where is all the Sunshine? Issues Ment Health Nurs. 2010;31(6):385-393. doi:10.3109/01612840903437657
  • Sintzel MB, Rametta M, Reder AT. Vitamin D and Multiple Sclerosis: A Comprehensive Review. Neurol Ther. 2017;7(1):59-85. doi:10.1007/s40120-017-0086-4
  • Buell JS, Dawson-Hughes B. Vitamin D and Neurocognitive Dysfunction: Preventing “D”ecline? Mol Aspects Med. 2008;29(6):415-422. doi:10.1016/j.mam.2008.05.001
  • Wilkins CH, Sheline YI, Roe CM, Birge SJ, Morris JC. Vitamin D deficiency is associated with low mood and worse cognitive performance in older adults. Am J Geriatr Psychiatry. 2006;14(12):1032-1040. doi:10.1097/01.JGP.0000240986.74642.7c
  • Naeem Z. Vitamin D Deficiency- An Ignored Epidemic. Int J Health Sci (Qassim). 2010;4(1):V-VI.
  • Vitamin D Deficiency: Symptoms & Treatment. Accessed January 21, 2021.
  • Vitamin D recommendations | International Osteoporosis Foundation. Accessed January 21, 2021.
  • Calame W, Street L, Hulshof T. Vitamin D Serum Levels in the UK Population, including a Mathematical Approach to Evaluate the Impact of Vitamin D Fortified Ready-to-Eat Breakfast Cereals: Application of the NDNS Database. Nutrients. 2020;12(6). doi:10.3390/nu12061868
  • Vitamin D toxicity: What if you get too much? Mayo Clinic. Accessed January 21, 2021.
  • Fernandes de Abreu DA, Eyles D, Féron F. Vitamin D, a neuro-immunomodulator: implications for neurodegenerative and autoimmune diseases. Psychoneuroendocrinology. 2009;34 Suppl 1:S265-277. doi:10.1016/j.psyneuen.2009.05.023
  • Nair R, Maseeh A. Vitamin D: The “sunshine” vitamin. J Pharmacol Pharmacother. 2012;3(2):118-126. doi:10.4103/0976-500X.95506

  • Smart Supplement
  • Braincare Journal
Rest of World
© 2022
This product is not designed to replace a varied and balanced diet. Do not exceed stated dose. If you are pregnant, breastfeeding or taking any medication, please consult your doctor before use. Do not use it if the seal has been tampered with. Store in a cool, dry place. Keep out of reach of children.
* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease