Last update
3/14/2026
Reviewed By
Overview
SCIENTIFIC SCORE
Questionable
Based on 4 Researches
6.4
USERS' SCORE
Good
Based on 14 Reviews
8.5
Supplement Facts
Serving Size: 1 Softgel
Amount Per Serving
%DV
Vitamin D3
25 mcg (1,000 IU)
125%
Top Medical Research Studies
0
We conducted a study to see if high-dose vitamin D3 could improve vascular health and reduce fatigue in individuals suffering from chronic fatigue syndrome (CFS). This was a well-structured trial involving 50 participants, all of whom met specific diagnostic criteria for CFS. Participants were divided into two groups: one received 100,000 units of vitamin D3 every two months, while the other received a placebo over a period of six months.
Despite a noticeable increase of 22 nmol/L in vitamin D levels for those who received the treatment compared to the placebo group, we found no significant benefits. There was no change in arterial stiffness, a key vascular health indicator, nor improvements in overall fatigue as measured by the Piper Fatigue scale.
In essence, our findings indicate that high-dose oral vitamin D3 does not offer the hoped-for relief in vascular function or fatigue for patients with chronic fatigue syndrome. This suggests that other therapeutic options may need to be explored for individuals suffering from this condition.
Despite a noticeable increase of 22 nmol/L in vitamin D levels for those who received the treatment compared to the placebo group, we found no significant benefits. There was no change in arterial stiffness, a key vascular health indicator, nor improvements in overall fatigue as measured by the Piper Fatigue scale.
In essence, our findings indicate that high-dose oral vitamin D3 does not offer the hoped-for relief in vascular function or fatigue for patients with chronic fatigue syndrome. This suggests that other therapeutic options may need to be explored for individuals suffering from this condition.
Read More
9.5
Vitamin D treatment enhances alertness
We explored the impact of vitamin D treatment on a case of excessive daytime sleepiness (EDS), specifically in the context of chronic fatigue syndrome. A 28-year-old woman was found to have low levels of vitamin D after experiencing four months of overwhelming fatigue and sleepiness, despite being tested for sleep disorders.
After starting vitamin D supplementation, her condition improved remarkably within just two weeks. Along with a boost in alertness, her associated symptoms like muscle pain and headaches began to fade. By the end of the treatment, her score on the Epworth Sleepiness Scale, which measures daytime sleepiness, dropped significantly, indicating much better daytime function.
This case suggests that vitamin D may play a role in improving symptoms commonly linked to chronic fatigue syndrome. While more research is needed to fully understand the mechanisms behind this improvement, our findings open the door to potentially screening patients with chronic fatigue for vitamin D deficiency to expedite treatment.
After starting vitamin D supplementation, her condition improved remarkably within just two weeks. Along with a boost in alertness, her associated symptoms like muscle pain and headaches began to fade. By the end of the treatment, her score on the Epworth Sleepiness Scale, which measures daytime sleepiness, dropped significantly, indicating much better daytime function.
This case suggests that vitamin D may play a role in improving symptoms commonly linked to chronic fatigue syndrome. While more research is needed to fully understand the mechanisms behind this improvement, our findings open the door to potentially screening patients with chronic fatigue for vitamin D deficiency to expedite treatment.
Read More
8
We conducted a double-blind, placebo-controlled trial to evaluate the effects of an oral food supplement (OFS) on long COVID patients, particularly focusing on chronic inflammation and fatigue. The supplement included components like rosehip, propolis, royal jelly, and zinc, with vitamin C being a key ingredient.
Through our two-month study, which involved giving participants either the OFS or a placebo, we made some interesting observations. Notably, patients who took the OFS experienced a significant reduction in inflammatory markers, which are often linked to chronic fatigue syndrome. This included improvements in the neutrophil-to-lymphocyte and monocyte-to-lymphocyte ratios.
We also noted a substantial increase in vitamin D levels among those taking the supplement, which correlated with enhanced quality of life and decreased fatigue as measured by the fatigue severity scale. Our findings suggest that the combination of ingredients in the OFS, particularly its vitamin D content, can help alleviate some symptoms associated with long COVID, especially chronic fatigue.
However, since the supplement included multiple active ingredients, isolating the specific impact of vitamin D on chronic fatigue syndrome is challenging. Still, the overall results indicate positive changes for patients dealing with the lingering effects of COVID.
Through our two-month study, which involved giving participants either the OFS or a placebo, we made some interesting observations. Notably, patients who took the OFS experienced a significant reduction in inflammatory markers, which are often linked to chronic fatigue syndrome. This included improvements in the neutrophil-to-lymphocyte and monocyte-to-lymphocyte ratios.
We also noted a substantial increase in vitamin D levels among those taking the supplement, which correlated with enhanced quality of life and decreased fatigue as measured by the fatigue severity scale. Our findings suggest that the combination of ingredients in the OFS, particularly its vitamin D content, can help alleviate some symptoms associated with long COVID, especially chronic fatigue.
However, since the supplement included multiple active ingredients, isolating the specific impact of vitamin D on chronic fatigue syndrome is challenging. Still, the overall results indicate positive changes for patients dealing with the lingering effects of COVID.
Read More
Most Useful Reviews
9
Fatigue reduction noted
42 people found this helpful
I recommend this concentration of D3 for children. I’ve found that the dosage is essential for combating chronic fatigue syndrome. Higher doses have shown positive effects like increased energy and immune function.
Read More
9
Eliminated constant fatigue
1 people found this helpful
In my region, vitamin D3 is essential due to lack of sunlight. After my wife and I began taking it, our chronic fatigue syndrome faded, and we feel great now. I trust this brand completely.
Read More
10
Restored energy
In autumn, my husband suffered from chronic fatigue, lethargy, and depression due to vitamin D and folic acid deficiencies. After his doctor prescribed vitamin D and folic acid, he felt energised again within two weeks. The sleep duration decreased, and his immunity improved. We are thrilled with the results, and we always opt for Solgar vitamins.
Read More
Medical Researches
SCIENTIFIC SCORE
Questionable
Based on 4 Researches
6.4
- All Researches
9.5
Vitamin D treatment enhances alertness
We explored the impact of vitamin D treatment on a case of excessive daytime sleepiness (EDS), specifically in the context of chronic fatigue syndrome. A 28-year-old woman was found to have low levels of vitamin D after experiencing four months of overwhelming fatigue and sleepiness, despite being tested for sleep disorders.
After starting vitamin D supplementation, her condition improved remarkably within just two weeks. Along with a boost in alertness, her associated symptoms like muscle pain and headaches began to fade. By the end of the treatment, her score on the Epworth Sleepiness Scale, which measures daytime sleepiness, dropped significantly, indicating much better daytime function.
This case suggests that vitamin D may play a role in improving symptoms commonly linked to chronic fatigue syndrome. While more research is needed to fully understand the mechanisms behind this improvement, our findings open the door to potentially screening patients with chronic fatigue for vitamin D deficiency to expedite treatment.
After starting vitamin D supplementation, her condition improved remarkably within just two weeks. Along with a boost in alertness, her associated symptoms like muscle pain and headaches began to fade. By the end of the treatment, her score on the Epworth Sleepiness Scale, which measures daytime sleepiness, dropped significantly, indicating much better daytime function.
This case suggests that vitamin D may play a role in improving symptoms commonly linked to chronic fatigue syndrome. While more research is needed to fully understand the mechanisms behind this improvement, our findings open the door to potentially screening patients with chronic fatigue for vitamin D deficiency to expedite treatment.
Read More
8
We conducted a double-blind, placebo-controlled trial to evaluate the effects of an oral food supplement (OFS) on long COVID patients, particularly focusing on chronic inflammation and fatigue. The supplement included components like rosehip, propolis, royal jelly, and zinc, with vitamin C being a key ingredient.
Through our two-month study, which involved giving participants either the OFS or a placebo, we made some interesting observations. Notably, patients who took the OFS experienced a significant reduction in inflammatory markers, which are often linked to chronic fatigue syndrome. This included improvements in the neutrophil-to-lymphocyte and monocyte-to-lymphocyte ratios.
We also noted a substantial increase in vitamin D levels among those taking the supplement, which correlated with enhanced quality of life and decreased fatigue as measured by the fatigue severity scale. Our findings suggest that the combination of ingredients in the OFS, particularly its vitamin D content, can help alleviate some symptoms associated with long COVID, especially chronic fatigue.
However, since the supplement included multiple active ingredients, isolating the specific impact of vitamin D on chronic fatigue syndrome is challenging. Still, the overall results indicate positive changes for patients dealing with the lingering effects of COVID.
Through our two-month study, which involved giving participants either the OFS or a placebo, we made some interesting observations. Notably, patients who took the OFS experienced a significant reduction in inflammatory markers, which are often linked to chronic fatigue syndrome. This included improvements in the neutrophil-to-lymphocyte and monocyte-to-lymphocyte ratios.
We also noted a substantial increase in vitamin D levels among those taking the supplement, which correlated with enhanced quality of life and decreased fatigue as measured by the fatigue severity scale. Our findings suggest that the combination of ingredients in the OFS, particularly its vitamin D content, can help alleviate some symptoms associated with long COVID, especially chronic fatigue.
However, since the supplement included multiple active ingredients, isolating the specific impact of vitamin D on chronic fatigue syndrome is challenging. Still, the overall results indicate positive changes for patients dealing with the lingering effects of COVID.
Read More
8
Beta-glucan shows cognitive improvements
We conducted a randomized, double-blind, placebo-controlled trial to explore how yeast beta-glucan, along with multivitamins, affects individuals suffering from Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). In our study, 65 participants received either beta-glucan combined with vitamins and zinc or a placebo for 36 weeks.
Interestingly, while our primary focus was on beta-glucan, which was shown to significantly improve cognitive fatigue, the role of vitamin D3 within this combination was not clearly established. This makes it challenging to directly assess the impact of vitamin D3 alone on chronic fatigue syndrome outcomes.
Overall, we discovered that beta-glucan supplementation could positively influence cognitive fatigue, offering promise for future research on nutritional support in ME/CFS patients. However, definitive conclusions about vitamin D3's effectiveness remain inconclusive due to the combined nature of the treatment.
Interestingly, while our primary focus was on beta-glucan, which was shown to significantly improve cognitive fatigue, the role of vitamin D3 within this combination was not clearly established. This makes it challenging to directly assess the impact of vitamin D3 alone on chronic fatigue syndrome outcomes.
Overall, we discovered that beta-glucan supplementation could positively influence cognitive fatigue, offering promise for future research on nutritional support in ME/CFS patients. However, definitive conclusions about vitamin D3's effectiveness remain inconclusive due to the combined nature of the treatment.
Read More
0
We conducted a study to see if high-dose vitamin D3 could improve vascular health and reduce fatigue in individuals suffering from chronic fatigue syndrome (CFS). This was a well-structured trial involving 50 participants, all of whom met specific diagnostic criteria for CFS. Participants were divided into two groups: one received 100,000 units of vitamin D3 every two months, while the other received a placebo over a period of six months.
Despite a noticeable increase of 22 nmol/L in vitamin D levels for those who received the treatment compared to the placebo group, we found no significant benefits. There was no change in arterial stiffness, a key vascular health indicator, nor improvements in overall fatigue as measured by the Piper Fatigue scale.
In essence, our findings indicate that high-dose oral vitamin D3 does not offer the hoped-for relief in vascular function or fatigue for patients with chronic fatigue syndrome. This suggests that other therapeutic options may need to be explored for individuals suffering from this condition.
Despite a noticeable increase of 22 nmol/L in vitamin D levels for those who received the treatment compared to the placebo group, we found no significant benefits. There was no change in arterial stiffness, a key vascular health indicator, nor improvements in overall fatigue as measured by the Piper Fatigue scale.
In essence, our findings indicate that high-dose oral vitamin D3 does not offer the hoped-for relief in vascular function or fatigue for patients with chronic fatigue syndrome. This suggests that other therapeutic options may need to be explored for individuals suffering from this condition.
Read More
User Reviews
USERS' SCORE
Good
Based on 14 Reviews
8.5
- All Reviews
- Positive Reviews
- Negative Reviews
9
Fatigue reduction noted
42 people found this helpful
I recommend this concentration of D3 for children. I’ve found that the dosage is essential for combating chronic fatigue syndrome. Higher doses have shown positive effects like increased energy and immune function.
Read More
9
Eliminated constant fatigue
1 people found this helpful
In my region, vitamin D3 is essential due to lack of sunlight. After my wife and I began taking it, our chronic fatigue syndrome faded, and we feel great now. I trust this brand completely.
Read More
10
Restored energy
In autumn, my husband suffered from chronic fatigue, lethargy, and depression due to vitamin D and folic acid deficiencies. After his doctor prescribed vitamin D and folic acid, he felt energised again within two weeks. The sleep duration decreased, and his immunity improved. We are thrilled with the results, and we always opt for Solgar vitamins.
Read More
9
Enhanced cheerfulness
After starting this vitamin, my energy levels skyrocketed! I feel more cheerful and energetic, and my chronic fatigue syndrome has improved. However, it's best taken before dinner to avoid sleep disturbances at night.
Read More
9
Boosted energy
This excellent medication provided me with an immediate surge of energy. My chronic fatigue has vanished.
Read More
Frequently Asked Questions
9
Less emotional decline
2 people found this helpful
Living in the far north, November and December are tough months with no sun. Since beginning vitamin D in 2019, I've found these months much easier. My chronic fatigue syndrome has improved, and I no longer struggle as much.
6
Less fatigue noted
I've previously taken Solgar D3, but I find it more affordable online. Combining it with Omega 3, I noticed less fatigue and stronger nails. Although I deal with chronic fatigue syndrome, my energy levels have improved with continuous use, which I maintain with occasional breaks.
0
We conducted a study to see if high-dose vitamin D3 could improve vascular health and reduce fatigue in individuals suffering from chronic fatigue syndrome (CFS). This was a well-structured trial involving 50 participants, all of whom met specific diagnostic criteria for CFS. Participants were divided into two groups: one received 100,000 units of vitamin D3 every two months, while the other received a placebo over a period of six months.
Despite a noticeable increase of 22 nmol/L in vitamin D levels for those who received the treatment compared to the placebo group, we found no significant benefits. There was no change in arterial stiffness, a key vascular health indicator, nor improvements in overall fatigue as measured by the Piper Fatigue scale.
In essence, our findings indicate that high-dose oral vitamin D3 does not offer the hoped-for relief in vascular function or fatigue for patients with chronic fatigue syndrome. This suggests that other therapeutic options may need to be explored for individuals suffering from this condition.
Despite a noticeable increase of 22 nmol/L in vitamin D levels for those who received the treatment compared to the placebo group, we found no significant benefits. There was no change in arterial stiffness, a key vascular health indicator, nor improvements in overall fatigue as measured by the Piper Fatigue scale.
In essence, our findings indicate that high-dose oral vitamin D3 does not offer the hoped-for relief in vascular function or fatigue for patients with chronic fatigue syndrome. This suggests that other therapeutic options may need to be explored for individuals suffering from this condition.
9.5
Vitamin D treatment enhances alertness
We explored the impact of vitamin D treatment on a case of excessive daytime sleepiness (EDS), specifically in the context of chronic fatigue syndrome. A 28-year-old woman was found to have low levels of vitamin D after experiencing four months of overwhelming fatigue and sleepiness, despite being tested for sleep disorders.
After starting vitamin D supplementation, her condition improved remarkably within just two weeks. Along with a boost in alertness, her associated symptoms like muscle pain and headaches began to fade. By the end of the treatment, her score on the Epworth Sleepiness Scale, which measures daytime sleepiness, dropped significantly, indicating much better daytime function.
This case suggests that vitamin D may play a role in improving symptoms commonly linked to chronic fatigue syndrome. While more research is needed to fully understand the mechanisms behind this improvement, our findings open the door to potentially screening patients with chronic fatigue for vitamin D deficiency to expedite treatment.
After starting vitamin D supplementation, her condition improved remarkably within just two weeks. Along with a boost in alertness, her associated symptoms like muscle pain and headaches began to fade. By the end of the treatment, her score on the Epworth Sleepiness Scale, which measures daytime sleepiness, dropped significantly, indicating much better daytime function.
This case suggests that vitamin D may play a role in improving symptoms commonly linked to chronic fatigue syndrome. While more research is needed to fully understand the mechanisms behind this improvement, our findings open the door to potentially screening patients with chronic fatigue for vitamin D deficiency to expedite treatment.
References
- Noce A, Marrone G, Di Lauro M, Vita C, Montalto G, et al. Potential Anti-Inflammatory and Anti-Fatigue Effects of an Oral Food Supplement in Long COVID Patients. Pharmaceuticals (Basel). 2024;17. 10.3390/ph17040463
- Witham MD, Adams F, McSwiggan S, Kennedy G, Kabir G, et al. Effect of intermittent vitamin D3 on vascular function and symptoms in chronic fatigue syndrome--a randomised controlled trial. Nutr Metab Cardiovasc Dis. 2015;25:287. 10.1016/j.numecd.2014.10.007
- McCarty DE. Resolution of hypersomnia following identification and treatment of vitamin d deficiency. J Clin Sleep Med. 2010;6:605. PubMed
- Lacasa M, Alegre-Martin J, Sentañes RS, Varela-Sende L, Jurek J, et al. Yeast Beta-Glucan Supplementation with Multivitamins Attenuates Cognitive Impairments in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial. Nutrients. 2023;15. 10.3390/nu15214504
Data last updated:
