Vitamin D helps absorb calcium which helps to build strong bones and moves muscles. The body needs vitamin D for its immune system to fight off bacteria and viruses, as well as nerve health in the nervous system.
The effects of vitamin D on the body have been shown to improve depression symptoms, blood pressure, decrease cholesterol levels, heart and bone health. Vitamin D is fat soluble and it is stored in fat cells within the body, that is to say taking vitamin D either in a supplement or eating foods high in vitamin D will not help a person lose weight.
This vitamin is called the sunshine vitamin because it is mainly produced in the skin when you are in sunlight. Although, this vitamin can also be consumed through a person’s diet.
Vitamin D is primarily obtained through three main sources: food, sunlight, and supplements. When it comes to digestion and processing in the body, here is a breakdown of how each source contributes to the absorption and utilization of vitamin D:
Food:
Vitamin D can be found naturally in certain foods such as salmon, tuna, mackerel, beef liver, and egg yolks.
Foods like milk, cereal, and some orange juices are often fortified with vitamin D2 and D3 to ensure an adequate intake.
Once consumed, vitamin D from food is absorbed in the intestines with the help of probiotic bacteria. It is crucial to have good gut health to be able to convert and absorb vit D.
Sunlight:
When exposed to sunlight, the skin produces vitamin D3 through a series of reactions triggered by ultraviolet B (UVB) rays.
The body’s vitamin D receptor cells convert cholesterol in the skin into vitamin D3 when exposed to sunlight.
This synthesized vitamin D3 is then utilized by the body.
Supplements:
Vitamin D supplements are available in pill or liquid form for those who may have issues with fat absorption, lactose intolerance, or limited sun exposure.
After ingestion, these supplements provide additional vitamin D that can be absorbed by the body.
Processing in the Body:
Once vitamin D is obtained from any of these sources (food, sunlight, or supplements), it is stored in fat cells until needed.
The liver and kidneys play a crucial role in converting stored vitamin D into its active form called calcitriol through a process known as hydroxylation.
This active form of vitamin D is essential for various bodily functions including calcium absorption for bone health.
In summary, the digestion and processing of vitamin D involve absorption from food in the intestines, synthesis from sunlight exposure on the skin, and supplementation when necessary to meet daily requirements.
Daily recommended amount
The dietary reference intakes are created by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies. Daily vitamin D amounts depend on age and below is the chart to show where a person should fall to get the correct amount of vitamin D.
After taking a blood test these are the levels to look at when comparing to see if the person is getting adequate vitamin D (U.S department of Health and Human Services):
Levels of 50 nmol/L (20 ng/mL) or above are adequate for most people for bone and overall health.
Levels below 30 nmol/L (12 ng/mL) are too low and might weaken your bones and affect your health.
Levels above 125 nmol/L (50 ng/mL) are too high and might cause health problems.
Deficiency
Several factors can contribute to an increased risk of developing vitamin D deficiency. These include:
Age: Older adults, especially those over the age of 65, are at a higher risk of vitamin D deficiency due to reduced skin synthesis of vitamin D and decreased dietary intake.
Skin Color: Individuals with darker skin tones have higher levels of melanin, which can reduce the skin’s ability to produce vitamin D in response to sunlight exposure. This puts them at a greater risk of deficiency.
Athletes: research shows that extra supplementation with vit D is crucial for people with significant sport load on the body
Limited Sun Exposure: People who have limited exposure to sunlight, either due to living in regions with little sunlight or spending most of their time indoors, may not produce enough vitamin D through sun exposure alone.
Dietary Factors: Individuals following strict vegan diets or those with limited intake of foods rich in vitamin D such as fatty fish, fish liver oils, egg yolks, and fortified foods are at risk of deficiency.
Obesity: Obesity can affect the bioavailability and utilization of vitamin D in the body, leading to a higher prevalence of deficiency among obese individuals.
Medical Conditions: Certain medical conditions like malabsorption disorders (e.g., celiac disease, Crohn’s disease), liver or kidney diseases, and osteoporosis can interfere with the absorption and metabolism of vitamin D.
Medications: Some medications like anticonvulsants, glucocorticoids, and certain weight-loss drugs can impact vitamin D levels by either reducing absorption or increasing breakdown.
A blood test is a great way to see how much vitamin D is in the blood. When an individual has low amounts of vitamin D they are susceptible to osteoporosis, which is a disease that makes bones thinner, easier to break and older women are more vulnerable. While looking at children with vitamin D deficiency causes rickets which is where the bones in the body become weak/soft, deformed or/and painful for the child. Then in teens and adults who have vitamin D deficiency the outcome is osteomalacia disorder which causes bone pain and muscle weakness.
Low vitamin D status could negatively impact the health and training efficiency of athletes. Research to date suggests that certain athletes are at risk for suboptimal vitamin D status, which may increase risks for stress fractures, acute illness, and suboptimal muscle function.
Vit D deficiency is a problem globally. Within the USA “one out of four people have vitamin D blood levels that are too low or inadequate for bone and overall health”. The individuals that are most at risk: older adults, pregnant women, African Americans, Hispanics, obese adults, and infants/children. Another group of individuals that are at high risk for vitamin D deficiency are people with limited fat absorption due to disease such as Chron’s, celiac, and/or ulcerative colitis.
Toxicity signs & symptoms
Vitamin D toxicity is very rare but it’s usually due to diet because intoxication can’t happen from the sun since the cells in the skin will destroy any excess vitamin D. In certain cases having high levels of vitamin D can cause kidney stones, nausea, increased thirst and urination. Then in extreme cases levels of calcium are found in the blood which could lead to kidney failure, irregular heartbeat and possible death.
Overall, vitamin D is crucial for our health and survival. Talk to our ImmuneLine specialists to see if you have sufficient levels and if you need supplementation.
References:
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