Adequate levels of this vitamin ensure a good balance of sex hormones (oestrogen in women, testosterone in men), provided approximation of your ideal weight and a strong immune system.
Today we will learn how vitamin D influences excess weight loss, what concentration is required for you to maintain adequate levels of sex hormones, and how it provides immune protection and, ultimately, anti-ageing.
Vitamin D3 can be formed when a chemical reaction occurs in human skin, as a steroid called 7-dehydrocholesterol is broken down by the sun's UVB light or so-called "tanning" rays. However, the amount of vitamin absorbed can vary greatly.
When we synthesise vitamin D from the sun, it is 100% bound to the D-binding protein and its effects last much longer than the concentration obtained from vitamin D-containing foods or supplementation.
The following are conditions that decrease exposure to UVB light and thus vitamin D absorption:
- Use of sunscreen: properly applied sunscreen can reduce vitamin D absorption by more than 90%.
- Wearing full clothing that covers the skin.
- Spending little time outdoors.
It should be noted that since ultraviolet rays can cause skin cancer, it is important to avoid excessive exposure to the sun and sunbeds should generally not be used.
Let's Take a Look at How Vitamin D Makes You Look Sexy!
- The Connection Between Vitamin D and Excess Weight Loss
Several studies have shown that there is a strong possibility that overweight people are vitamin D deficient because vitamin D is fat-soluble, so it gets trapped in stored fat and can't do its job.
A study published by the US National Library of Medicine showed that after 6 weeks of intervention, mean weight, body mass index (BMI), waist circumference (WC) and hip circumference (WCa) decreased significantly. Previous studies have shown that vitamin D deficiency was more prevalent in obese people and that there was an inverse association between vitamin D and BMI and BCC. The relationship between vitamin D and lipid profiles, such as glycaemic indices, anthropometric indices, C-reactive protein (CRP) and blood pressure, is unclear and requires further study in the future.
Adequate levels of vitamin D ensure that insulin reaches the tissues as it is insulin that "pushes" glucose into the cells and if there is not enough, both insulin and glucose are stored as fat. In this sense, a person who is insulin resistant is likely to have difficulty getting vitamin D into the cells.
The good news is that by losing excess weight, vitamin D is released from adipose tissue and it's like opening the floodgates to where it's intended to go, as demonstrated in a study published in 2021.
14 male volunteers fasted for 8 days, which resulted in increases in 24,25(OH)2D3 and 3-epi-25(OH)D3 levels, implying that fasting stimulates vitamin D metabolism. The effects of exercise on serum vitamin D metabolites, which are more pronounced after fasting and in subjects with serum 25(OH)D3 levels above 25 ng/mL, support the notion that fasting and exercise increase vitamin D metabolism.
- Vitamin D and Your Hormonal Health
After it is synthesised in the skin, vitamin D is stored in body fat and released into the bloodstream and then converted into a HORMONE. Vitamin D transformed into a hormone regulates 5% or more of the encoded protein in the human genome. Imagine walking around without testosterone if you are a man or without oestrogen if you are a woman; this is a steroid hormone, not a simple vitamin.
Vitamin D carries hormones, including sex hormones, throughout your body. For this effect, the concentration of vitamin D in a woman's body should be between 70 and 90 nmol/L of blood.
Another study shows that the active metabolite of vitamin D, 1,25-dihydroxyvitamin D, regulates a few enzymes involved in the production of steroid hormones, including adrenal steroid hormones and sex hormones, as well as sex hormone signalling.
- Immunological Function
There are vitamin D receptors on immune cells and the reason for this is that when the vitamin D hormone binds to a receptor it activates several genes and as we know genes act, for example, by regulating immune function.
There have been about 25 studies in which vitamin D deficient people have been given daily or weekly vitamin D and in more than half of the people treated, the risk of respiratory tract infection was reduced by vitamin supplementation alone. Even in people who had normal vitamin D levels, supplementation provided a protective effect, reducing the risk of infection by a further 10%.
- Anti-Ageing Effect
According to a study published in the US National Library of Medicine, active metabolites of vitamin D3 (D3) and lumisterol (L3) exert various anti-ageing and photoprotective effects on the skin. These are achieved through immunomodulation and include anti-inflammatory actions, regulation of keratinocyte proliferation and differentiation programmes to build the epidermal barrier necessary to maintain skin homeostasis.
In addition, they induce antioxidant responses, inhibit DNA damage, and induce DNA repair mechanisms to attenuate premature skin ageing and cancer-genesis.
Therefore, the active forms of vitamin D3, including its canonical (1,25(OH)2D3) and non-canonical (CYP11A1 derivatives), as well as L3 derivatives, are promising agents for the prevention, attenuation or treatment of premature skin ageing and could be administered orally and/or topically.
Finally, it should be noted that sunbathing in a sunny office or driving a car does not help to obtain vitamin D, as window glass completely blocks UVB ultraviolet light.
Risk of Vitamin D Overdose
The maximum tolerable intake for humans has been estimated at 4000 IU per day, but studies have shown that even people who have ingested 10000 IU per day for years have not suffered from hypercalcaemia, or any problems related to this intake. However, too much vitamin D is "said" to be toxic.
Ideally, however, it is best to have a blood test where vitamin D levels can be measured. There is a tendency for people with levels greater than 60 nanomoles per ml of blood to have slightly elevated calcium levels without this being a cause for concern. However, there are meta-analyses of studies where vitamin K1 and/or K2 have been tested and found to both improve bone mineral density and protect against hypercalcaemia.
If you are wondering what the difference is between vitamin K1 and K2, the answer is that vitamin K1 goes to your liver and is involved in blood clotting, and when there is enough vitamin K1 circulating in the body, it moves calcium out of the bloodstream and into places where it needs to work, be it the bones or muscles.
Vitamin K2 stays in the periphery and does not go to the liver, but merely takes calcium out of the bloodstream and into the bones and muscles. So when taking a supplement, you can choose one or the other, or both a couple of times a week.
Vitamin K1 is found in dark green leafy vegetables such as spinach and kale, mainly, and that's how easy supplementation can be if you include them in your weekly menu.
Vitamin K2 is not so easily found in the Western diet, it is mostly found in some fermented soy products, such as natto, for example. For this reason, it is recommended if you are going to use a vitamin D3 supplement that contains vitamin K2.
Food Sources Containing Vitamin D
Few foods are naturally rich in vitamin D3. The best sources are fatty fish meat and fish liver oils. Egg yolks, cheese and beef liver contain smaller amounts.
Some mushrooms contain vitamin D2, and some mushrooms sold in shops contain higher amounts of D2 due to intentional exposure to large amounts of ultraviolet light.
Many foods and supplements are fortified with vitamin D, such as dairy products and cereals. You would find the highest concentrations in descending order,
Cod liver oil
Salmon
Swordfish
Tuna
Orange juice fortified with vitamin D
Vitamin D-fortified dairy products and vegetable milks
Sardines
Beef liver
Egg yolk
Fortified cereals