Vitamin D is an essential nutrient because our bodies cannot manufacture it. Therefore, we need to consume vitamin D through sun exposure or food. Interestingly vitamin D is actually a hormone, rather than a vitamin. Currently, around 42% of the US population is deficient in vitamin D, particularly people over the age of 65. Vitamin D is critical for a healthy immune system and for supporting healthy inflammation. Additionally, the effects of vitamin D seem to be cumulative. One study found a strong correlation between low vitamin D levels and vulnerability to contract viral pathogens.
Bones and Microbes - A New Story
Doctors used to think that vitamin D only impacted bone health because a deficiency can lead to rickets in children, and osteoporosis in adults. This all changed in the 1980s when researchers discovered that vitamin D3 played a role in supporting healthy inflammatory pathways and boosting immune system function.
We now know that vitamin D also plays a role in keeping gut microbes healthy by increasing the diversity and number of healthy microbes. Interestingly, one study published in the Journal of Gastroenterology exposed that patients with irritable bowel disease (IBD) experienced more symptoms during the winter months suggesting the influence of vitamin D on gut health.
What Causes Low Vitamin D Levels?
Low vitamin D levels can happen for a variety of reasons. Most commonly, a lack of sunlight is the main reason. For people with darker skin tones, this problem is heightened as they require higher levels of vitamin D. Darker skin pigmentation blocks UVB rays that produce vitamin D. As a result, a massive 82% of people of color in the US are deficient in vitamin D. Consistently using high SPF sunscreen can also increase your risk of having a vitamin D deficiency.
Vitamin D deficiency can also occur when the kidneys are not functioning optimally. The kidneys are responsible for converting the pre-hormone calcifediol (25 (OH) D3) into bioavailable vitamin D. Additionally, calcifediol is produced in the liver, so liver impairment is another contributor to lower vitamin D levels. Additionally, gut problems and age impair vitamin D absorption.
Beat the Winter Blues
Vitamin D plays a role in the production of serotonin and dopamine, both required for us to feel happy. Therefore, it’s not surprising that researchers have found that low levels of vitamin D can contribute to developing seasonally affective disorders (SAD). The findings aren’t conclusive, but a small study found a correlation between low vitamin D levels and SAD.
Another 2014 study published in the journal Medical Hypotheses found that vitamin D played a role in the production of serotonin and dopamine, concluding that low levels of vitamin D could contribute to the development of SAD and depression.
3 Foods High in Vitamin D
Although sunlight is by far the best source of vitamin D, it’s not always possible to get out during the daylight hours. Therefore ensuring that you eat the right amount of vitamin D rich foods becomes more important. The top 3 foods that contain vitamin D are:
6 Vitamin D Deficiency Symptoms
Vitamin D deficiency is a big problem all over the world. Vitamin D is essential for all systems of the body to function properly. Therefore, ensuring adequate sunlight, food, and supplementation where necessary is crucial. Just one of these symptoms could signal a vitamin D deficiency:
Dose, Guidelines, and Safety
How much vitamin D should you take in winter? The US Institute of Medicine recommends a daily intake of 400-800IU. However, other studies have suggested that an intake of 1120-1680 IU is required to maintain sufficient vitamin D levels, especially in winter. Most experts will advise that your vitamin D levels should fall within the range of 20-50 ng/mL.
Vitamin D is fat-soluble so it’s best taken during a meal containing healthy fats. In one study, of 17 people, researchers found that taking vitamin D supplements with your largest meal of the day for 2-3 months could increase vitamin D blood levels by 50%.
Take Home Message
Vitamin D is essential for all-round health and wellbeing. If a person cannot obtain enough from the sunlight due to darker winter months or by eating adequate vitamin D-rich foods, supplementation may be necessary. Vitamin D has also been shown to boost mood and energy levels. This year we’ve all been indoors more than normal and should take extra steps to ensure that our vitamin D levels are sufficient over winter.
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