The authors conducted a systematic review and meta-analysis to explore the effects of vitamin D3 supplementation on strength performance among athletes. The findings indicate that while vitamin D3 supplementation was able to improve the vitamin D status of athletes, its impact on performance was less clear.
Overview
What did they find? The researchers performed a systematic review and meta-analysis of randomized controlled trials (RCTs) that investigated the effects of vitamin D3 supplementation on muscular strength in healthy athletes.
What did they test? Ten RCTs were included in the review. They found that vitamin D3 supplementation was able to improve the vitamin D status of athletes. However, of the four measures used to assess muscular strength, only quadriceps strength showed significant improvements following supplementation.
What does it mean for you? There may be some benefits to supplementing with vitamin D3 if you, or your athletes, have insufficient levels. Therefore, it could be beneficial to monitor athletes’ vitamin D status, especially during the winter month or if athletes train predominantly indoors.
What’s the problem?
You may have heard about vitamin D before and perhaps been told that it can help improve your performance. Since this is our first article covering vitamin D in REPS, I thought it would be valuable to provide some background information on this essential nutrient before diving into the study.
Vitamin D is a fat-soluble vitamin, also referred to as a pro-hormone, that plays a role in many bodily functions. It encompasses a group of substances, with the two main forms being vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D3 is the form most commonly found in foods, particularly animal products. It is also the form synthesized in the skin when exposed to ultraviolet B (UVB) radiation from the sun, which is the body's primary source of vitamin D3.
Both forms of vitamin D can be converted into the active form, 1,25-dihydroxyvitamin D (1,25(OH)D). This conversion occurs in two steps: first, in the liver, where 25-hydroxyvitamin D (25(OH)D) is formed; and second, in the kidneys where 25(OH)D is converted into 1,25(OH)D. Within the blood, 25(OH)D is the most common vitamin D metabolite and is considered the most useful indicator of vitamin D status 1. It is the indicator of vitamin D status typically used in research.
Vitamin D plays a role in numerous functions within the body. In fact, receptors for vitamin D have been found in most cells that have a nucleus in our bodies 2. It serves multiple functions within the body, such as bone mineralization and ensuring proper function of the nervous, immune, and cardiovascular systems. It also plays roles in hormone production, regulates various genes, and contributes to the functioning of the muscular system.
Given its involvement in these various functions, it is not surprising that there has been interest in its potential to enhance athletic performance. Many studies have investigated the potential impact of vitamin D on athletic performance, but its impact on athletic performance remains inconclusive.
Purpose
The purpose of this study was to build upon an earlier systematic review by incorporating additional strength measures and integrating the latest research, aiming to provide a more comprehensive and updated assessment of the impacts of vitamin D supplementation on healthy athletes.
