What is Vitamin D?
Vitamin D, is also known as the sunshine vitamin, is a fat-soluble vitamin that can be made in the skin after exposure to UVB radiation which converts the skin’s pre-vitamin D3 to Vitamin D3. In order to make vitamin D, the body needs UVB radiation (290-320 nm) to penetrate the skin.
The season of the year, the time of day, cloud cover, smog, skin melanin content, skin color, sunscreen and your age affect the amounts of vitamin D that you can form from sunshine. It’s also worth noting that UVB does not penetrate glass, so you can’t absorb it through the window.
The recommendation from the National Institute of Health is 5 to 30 minutes of sun exposure between 10 am and 4 pm, 2-7 days per week to the face, arms, hands and legs without sunscreen. This needs to be balanced with the fact that UV radiation is also a carcinogen, so while you need some, you need to be careful about sun burns (NIH, 2022).
Vitamin D is also available in food sources such as fatty fish (trout, salmon, tuna, mackerel), fish liver oils, beef liver, egg yolks and cheese. Mushrooms exposed to UVB light can also be sources of vitamin D. The daily recommended intake is 15 micrograms (600 IU) for adults up to age 70 and 20 micrograms (800 IU) for adults over 70 (NIH 2022). Supplements can be in the form of D2 (ergocalciferol) or D3 (cholecalciferol) with D3 being more effective at increasing blood levels compared to D2 (NIH 2025).
What is Lymphedema?
Lymphedema is a chronic swelling condition with a buildup of protein rich lymphatic fluid. It can be primary – in that it results from a defect in the lymphatic system or simply a lymphatic system that doesn’t work very well. Lymphedema can also occur as a result of an injury or surgery, which is known as secondary lymphedema. Common causes of secondary lymphedema are phlebolymphedema or as a result of cancer treatment. To find out more about how to reduce your risk of developing lymphedema, read about Risk Factors for Lymphedema.
What’s the Connection between Vitamin D and Lymphedema?
I was able to locate three human observational studies and one animal clinical trial. I’ll present the human trials first in chronological order which will help to explain our current understanding of the connection between vitamin D and lymphedema.
Study #1 Ă–zcan, 2019
This case-control study, conducted in Turkey included 80 women with breast cancer related lymphedema and 80 healthy controls. Blood tests for 25-hydroxyvitamin D3, calcium, phosphorus, alkaline phosphatase and parathormone levels were compared. 25-hydroxyvitamin D3, is the storage form of vitamin D in the body and a good test to measure the overall vitamin D status used to detect deficiencies. Vitamin D blood tests were taken only in Summer or Autumn to control for seasonal variations. A comparison between the two groups of women revealed that the women with lymphedema had lower vitamin D blood levels than the age-matched healthy controls. Of those with lymphedema, 25% had vitamin D deficiency and 60% had vitamin D insufficiency. The vitamin D levels were significantly lower in cases of stage 3 lymphedema compared to stage 1.
Study #2 Doruk Analan, 2020
The goal of this study was to evaluate blood levels of vitamin D (25-hydroxyvitamin D3) on the presence and severity of lymphedema, pain, disability and function in women with breast cancer related lymphedema. Seventy-one women post breast cancer treatment were included, of which thirty seven had lymphedema and thirty four served as the controls. This study did not find a correlation between vitamin D blood levels and the presence of lymphedema, the levels of pain, disability or physical functioning. The authors did note that most women with lymphedema in this study had only low-grade lymphedema which may have affected the results. No mention was made of the time of year that the blood draw took place that evaluated the vitamin D level.
Study #3, Karakiliç, 2025
This third study was also done in Turkey to assess for a correlation between vitamin D blood levels and lymphedema. A total of 603 women were included with 201 from each of three cohorts: those with breast cancer related lymphedema, those with breast cancer but no lymphedema and age-matched healthy controls.A chart audit took place in order to access the blood tests of serum. Only blood tests done in June, July or August were retrieved from chart audit.
A cohort comparison revealed significantly reduced vitamin D levels in individuals with lymphedema compared to both breast cancer survivors without lymphedema and healthy controls with the healthy controls having the highest vitamin D levels. There was also a strong negative correlation between vitamin D level and lymphedema stage, meaning that the lower the vitamin D level, the worse the lymphedema.
Animal Study of Vitamin D and Lymphedema, Aksöyler, 2024
In addition to human research, one animal study has explored the relationship with vitamin D and lymphedema. Forty-five Sprague-Dawley rats had surgery to remove a popliteal lymph node, an inguinal fat pad containing an inguinal lymph node and dissection of the main lymphatic duct from the neurovascular bundle.
One week later, a single dose of radiation therapy (20Gy) was applied to the surgical region. The rats were randomly assigned to either no supplement, pre- and post-operative calcitriol the active form of vitamin D (1,25-dihydroxy vitamin D3), or post-operative calcitriol.
Following the treatment micro-computed tomography was used to calculate the limb volume, and fluorescence lymphatic imaging was used to detect lymphedema. The group without calcitriol had a 75% incidence rate of lymphedema as compared to the pre-and post-surgical calcitriol with only 25% incidence. The treated group also had an increase in M2 macrophages and newly formed lymphatic vessels, while the control group had elevated M1 macrophages and collagen.
The authors differentiate the two types of macrophages as M1 being primarily a promoter of inflammation, tissue damage and other pro-inflammatory effects, while M2 are known for their anti-inflammatory effects.
Are there Risks to Too Much Vitamin D?
No side effects were noted in the above mentioned studies, but the human research were correlation studies and not clinical trials. But side-effects of excess vitamin D have been documented and include nausea, vomiting, muscle weakness, confusion, pain, loss of appetite, dehydration, excessive urination, thirst and kidney stones (NIH 2022). The upper level for vitamin D from both food and supplements together is 100 micrograms (4,000 IU) per day.
Bottom Line on Vitamin D and Lymphedema
Two out of three human correlation studies found a relationship between vitamin D insufficiency/deficiency and the presence of lymphedema in breast cancer survivors. The third correlation study did not show this relationship but did have more low-grade lymphedema and may not have controlled for the month of blood testing. These findings do not prove that low vitamin D caused lymphedema, or that vitamin D can be used as a treatment for lymphedema only that there is an association, known as a correlation.
The animal study provides proof of concept that vitamin D in the form of calcitriol supplementation may impact lymphedema development in surgery and radiation recipients. This may be of particular interest as a risk reduction strategy in an oncology population. The mechanism of action suggested to explain the relationship between is that vitamin D has been shown to suppress pro-inflammatory cytokines and can act to reduce chronic inflammation (Karakiliç, 2025).
Assessing vitamin D blood levels and counselling regarding vitamin D supplementation and/or dietary sources is a common practice for registered dietitians and physicians. If additional research can confirm this relationship between vitamin D and lymphedema this may become standard practice in all cancer patients. Vitamin D supplementation is easy, low cost, low risk and accessible, which makes it an easy to adopt practice. Further research would be most welcome to confirm the impact of this simple intervention on lymphedema risk and management.
Get your vitamin D blood levels checked and if low you can begin a vitamin D supplementation and/or dietary sources. Consult a registered dietitian if you have questions. In Canada, the Health Canada currently recommends that all Canadians over age 2 supplement 10 micrograms (400 IU) vitamin D every day in addition to diet (Health Canada, 2022).
References
Aksöyler D, Kozanoğlu E, Korkut M, Akpınar ÖF, Çaylı M, Yücel HC, Akalın B, Özdemir İ, Sağ FB, Solakoğlu S, Mayadağlı A, Arıncı RA, Losco L. Evaluation of the Effectiveness of Active Vitamin D Use in Experimental Rat Lymphedema Model. Medicina (Kaunas). 2024 Nov 1;60(11):1788.
Doruk Analan P, Kaya E. The Effect of Serum 25(OH)D3 Level on Breast Cancer-Related Lymphedema. Lymphat Res Biol. 2020 Feb;18(1):22-26.
Health Canada. Last updated May 2, 2022. Accessed Sept 5, 2025 https://www.canada.ca/en/health-canada/services/nutrients/vitamin-d.html
Karakilic GD, Selcuk MA. The Effect of Vitamin D Levels on Breast Cancer-Related Lymphedema. Lymphology. 2025;58(2):56-65.
NIH. Vitamin D. Last updated Nov 8, 2022. Accessed Sept 4, 2025.
NIH. Vitamin D Fact Sheet for Health Professionals. Last updated June 27, 2025. Accessed Sept 4, 2025.
Ă–zcan DS, Dalyan M, ErgĂĽl S, et al. Evaluation of Vitamin D Levels in Patients with Breast Cancer-related Lymphedema: An Observational Cross-sectional Study. Turk J Osteoporos. 2019 Dec 12;25(3):105-110
