- but the official recommendations are too low
According to an American study, individuals with higher blood levels of vitamin D are far less likely to develop type 2 diabetes and metabolic syndrome, the early stage of the disease, which is characterized by insulin resistance, hypertension, and elevated cholesterol levels. Because it takes many years for type 2 diabetes to develop, it is essential to have sufficiently high vitamin D levels from the early years in life. Both the new American study and earlier research point to the fact that it is not possible to obtain high blood levels of the nutrient without getting plenty of sun during the summer period and taking a high-dosed vitamin D supplement in the winter.
Our primary source of vitamin D is sunshine during the summer period. Nonetheless, many people have too little vitamin D because of factors such as too much indoor activity, not getting enough vitamin D during the winter, being overweight, using too much suncream, having dark skin (which reduces your vitamin D synthesis), and ageing. Studies have shown that high blood levels of vitamin D (as 25-hydroxyvitamin D) are associated with a reduced risk of developing type 2 diabetes. Science has not yet established the optimal levels for vitamin D, but researchers at the University of California San Diego School of Medicine and Seoul National University have come a step closer to breaking the curve for type 2 diabetes and overweight – and the two are mutually related.
Lack of vitamin D can increase your diabetes risk by 500 percent
The researchers followed 903 healthy men aged 74 years on average. None of the men showed any sign of type 2 diabetes or early stages of the disease while undergoing a physical examination during the period 1997-1999, where doctors measured blood levels of vitamin D and fasting blood sugar.
In the course of the study, the scientists diagnosed 47 new cases of type 2 diabetes and 337 new cases of pre-diabetes in the form of insulin resistance, where blood sugar levels were elevated but not enough for it to be type 2 diabetes. Then they compared the men’s blood levels of vitamin D and found that, among those whose vitamin D levels were in the range between 30-50 ng/ml (nannograms per ml.), there was a three times greater risk of developing type 2 diabetes. Men with levels below 30 ng/ml were up to five times more likely to develop the disease, compared with men, who had blood levels of vitamin D above 50 ng/ml. In other words, the risk of type diabetes went down, when vitamin D levels went up.
The results of this study support an earlier study of middle-aged Brazilian women.
Optimal blood levels of vitamin D
Based on their findings, the researchers conclude that levels of vitamin D should ideally be higher than 30 ng/ml, which is 10 ng/ml above the official American recommendations. In Denmark, the lower threshold value is 50 ng/ml. Some experts even believe that higher intake levels are needed and suggest 75-100 ng/ml for optimal disease prevention.
The need for vitamin D in the blood may be different from one person to another due to genetic factors. Diabetics have difficulty with activating the nutrient.
Supplements are necessary for preventing diabetes, cancer, and other diseases
One of the scientists behind the American study, Professor Cedric F. Garland, from Santiago School of Medicine, is a long-time advocate of vitamin D’s beneficial effect, which even includes the prevention of cancer in the breasts, lungs, and bladder.
In order to reach blood levels of 30 ng/ml, one would have to take 50-75 micrograms of vitamin D daily as a supplement. An ordinary vitamin pill does not come anywhere close to that. 50-75 micrograms of vitamin D is about the same amount as the body can produce from 10-15 minutes of exposure to sunlight in the summertime. From October through May, this is not possible at our latitude, as the sun sits too low in the sky. Because of that and because there is not all that much vitamin D in the diet, supplementation is needed.
Upper safe limit
There is a lively debate when it comes to the actual need for vitamin D, depending on age, skin type, BMI, genes, and a number of other factors. In terms of supplementation, the European Food Safety Authority (EFSA) has established the following safe upper intake levels:
- 25 micrograms (babies)
- 50 micrograms (children aged 1-10 years)
- 100 micrograms (older children and adults, including pregnant and lactating women)
According to Professor Cedric F. Garland from Santiago School of Medicine, it is safe to take high-dosed vitamin D supplements, but blood levels higher than 125 ng/ml may be associated with side effects such as nausea, constipation, weight loss, heart rhythm disturbances, and kidney damage.
Vitamin, supplements, and absorption
Vitamin D is lipid-soluble, which means that supplements with vitamin D in some kind of oil gives the best utilization of the nutrient. It is safe to take supplements with as much as 50-80 micrograms of vitamin D daily.
Scott LaFee. Vitamin D Deficiency Linked to Greater Risk of Diabetes. UC San Diego Health. April 2018
Plasma 25-hydroxyvitamin concentration and risk of type 2 diabetes and pre-diabetes. 12-year cohort study. PLoS One 2018
Eneida Boteon Schmitt et al. Vitamin D deficiency is associated with metabolic syndrome in postmenopausal women. Maturitas 2018
Sisley SR et al. Hypothalamic Vitamin D Improves Glucose Homeostasis and Reduces Weight. Diabetes 2016
Iowa State University: New promise for diabetics with vitamin D-deficiency. ScienceDaily. 2016
Pernille Lund. Sådan får du styr på dit blodsukker og din vægt. Ny Videnskab 2013
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