Meeting Vitamin D Requirements in White Caucasians at UK Latitudes: Providing a Choice.

The body gains vitamin D through both oral intake (diet/supplementation) and synthesis in skin upon exposure to ultraviolet radiation (UVR). Sun exposure is the major source for most people even though sun exposure is complex and limited by climate and culture. We aimed to quantify the sun exposure required to meet vitamin D targets year-round and determine whether this can be safely achieved in a simply defined manner in the UK as an alternative to increasing vitamin D oral intake. Data from observation (sun exposure, diet, and vitamin D status) and UVR intervention studies performed with white Caucasian adults were combined with modeled all-weather UVR climatology. Daily vitamin D effective UVR doses (all-weather) were calculated across the UK based on ten-year climatology for pre-defined lunchtime exposure regimes. Calculations then determined the time necessary to spend outdoors for the body to gain sufficient vitamin D levels for year-round needs without being sunburnt under differing exposure scenarios. Results show that, in specified conditions, white Caucasians across the UK need nine minutes of daily sunlight at lunchtime from March to September for 25(OH)D levels to remain ≥25 nmol/L throughout the winter. This assumes forearms and lower legs are exposed June-August, while in the remaining, cooler months only hands and face need be exposed. Exposing only the hands and face throughout the summer does not meet requirements.

Colour Counts: Sunlight and Skin Type as Drivers of Vitamin D Deficiency at UK Latitudes.

Sunlight exposure, with resulting cutaneous synthesis, is a major source of vitamin D for many, while dietary intake is low in modern diets. The constitutive pigment in skin determines skin type, observed as white, brown, or black skin. The melanin pigment absorbs ultraviolet radiation (UVR) and protects underlying skin from damage caused by UVR. It also reduces the UVR available for vitamin D synthesis in the skin. It has been shown that the white-skinned population of the UK are able to meet their vitamin D needs with short, daily lunchtime exposures to sunlight. We have followed the same methodology, based on a 10-year UK all-weather UVR climatology, observation (sun exposure, diet, vitamin D status), and UVR intervention studies with Fitzpatrick skin type V (brown) adults, to determine whether sunlight at UK latitudes could provide an adequate source of vitamin D for this section of the population. Results show that to meet vitamin D requirements, skin type V individuals in the UK need ~25 min daily sunlight at lunchtime, from March to September. This makes several assumptions, including that forearms and lower legs are exposed June-August; only exposing hands and face at this time is inadequate. For practical and cultural reasons, enhanced oral intake of vitamin D should be considered for this population.

Calcium channel blockers for primary Raynaud's phenomenon.

BACKGROUND: Calcium channel blockers are the most commonly prescribed drugs for people with primary Raynaud's phenomenon. Primary Raynaud's phenomenon is a common condition characterised by an exaggerated vasospastic response to cold or emotion: classically the digits (fingers and toes) turn white, then blue, then red. This is an update of the review first published in 2014. OBJECTIVES: To assess the effects of different calcium channel blockers for primary Raynaud's phenomenon as determined by attack rates, severity scores, participant-preference scores and physiological measurements. SEARCH METHODS: For this update the Cochrane Vascular Trial Search Co-ordinator searched the Specialised Register (last searched January 2016) and the Cochrane Register of Studies (CENTRAL) (2015, Issue 12). In addition the TSC searched clinical trials databases. SELECTION CRITERIA: Randomised controlled trials evaluating the effects of oral calcium channel blockers for the treatment of primary Raynaud's phenomenon. DATA COLLECTION AND ANALYSIS: Three review authors independently assessed the trials for inclusion and their quality, and extracted the data. Data extraction included adverse events. We contacted trial authors for missing data. MAIN RESULTS: We included seven randomised trials with 296 participants. Four trials examined nifedipine and the remainder nicardipine. Comparisons were with placebo in six trials and with both dazoxiben and placebo in one trial (only the nifedipine versus placebo data were used within this review). Treatment with oral calcium channel blockers was minimally effective in primary Raynaud's phenomenon at decreasing the frequency of attacks (standardised mean difference of 0.23; 95% confidence interval (CI) 0.08 to 0.38, P = 0.003). This translates to 1.72 (95% CI 0.60 to 2.84) fewer attacks per week on calcium channel blockers compared to placebo. One trial provided details on duration of attacks reporting no statistically significant difference between the nicardipine and placebo groups (no P value reported). Only two trials provided any detail of statistical comparisons of (unvalidated) severity scores between treatment groups: one of these trials (60 participants) reported a mean severity score of 1.55 on placebo and 1.36 on nicardipine, difference 0.2 (95% CI of difference 0 to 0.4, no P value reported) and the other trial (three participants only with primary Raynaud's phenomenon) reported a median severity score of 2 on both nicardipine and placebo treatment (P > 0.999) suggesting little effect on severity. Participant-preference scores were included in four trials, but in only two were results specific to participants with primary Raynaud's phenomenon, and scoring systems differed between trials: scores differed between treatments in only one trial, in which 33% of participants on placebo and 73% on nifedipine reported improvement in symptoms (P < 0.001). Physiological measurements were included as outcome measures in five trials (different methodologies were used in each): none of these trials found any statistically significant between-treatment group differences. Treatment with calcium channel blockers appeared to be associated with a number of adverse reactions, including headaches, flushing and oedema (swelling). Overall, the trials were classed as being at low or unclear risk of bias; and the quality of the evidence presented was moderate for number of attacks, very low for duration of attacks, high for severity scores and low for patient preference scores. AUTHORS' CONCLUSIONS: The randomised controlled trials included in this review provide moderate quality evidence that oral calcium channel blockers are minimally effective in the treatment of primary Raynaud's phenomenon as measured by the frequency of attacks and high-quality evidence that they have little effect on severity. We are unable to comment on duration of attacks or on patient preference due to the very low and low quality of evidence as a result of small sample sizes in the included studies and the variable data quality of outcome measures.

Calcium channel blockers for primary Raynaud's phenomenon.

BACKGROUND: Calcium channel blockers are the most commonly prescribed drugs for people with primary Raynaud's phenomenon. Primary Raynaud's phenomenon is a common condition characterised by an exaggerated vasospastic response to cold or emotion: classically the digits (fingers and toes) turn white, then blue, then red. OBJECTIVES: To assess the effects of different calcium channel blockers for primary Raynaud's phenomenon as determined by attack rates, severity scores, participant-preference scores and physiological measurements. SEARCH METHODS: The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator (TSC) searched the Specialised Register (last searched February 2013) and the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 1). In addition the TSC searched clinical trials databases. SELECTION CRITERIA: Randomised controlled trials evaluating the effects of oral calcium channel blockers for the treatment of primary Raynaud's phenomenon. DATA COLLECTION AND ANALYSIS: Three review authors independently assessed the trials for inclusion and their quality, and extracted the data. Data extraction included adverse events. We contacted trial authors for missing data. MAIN RESULTS: We included seven randomised trials with 296 participants. Although overall all the trials were classed as being at low or unclear risk of bias, the sample size of the included trials was small and there was unclear reporting of outcomes. Four trials examined nifedipine and the remainder nicardipine. Comparisons were with placebo in six trials and with both dazoxiben and placebo in one trial (only the nifedipine versus placebo data were used within this review). Treatment with oral calcium channel blockers was minimally effective in primary Raynaud's phenomenon at decreasing the frequency of attacks (standardised mean difference of 0.23; 95% confidence interval (CI) 0.08 to 0.38, P = 0.003). This translates to 1.72 (95% CI 0.60 to 2.84) fewer attacks per week on calcium channel blockers compared to placebo. One trial provided details on duration of attacks reporting no statistically significant difference between the nicardipine and placebo groups (no P value reported). Only two trials provided any detail of statistical comparisons of (unvalidated) severity scores between treatment groups: one of these trials (60 participants) reported a mean severity score of 1.55 on placebo and 1.36 on nicardipine, difference 0.2 (95% CI of difference 0 to 0.4, no P value reported) and the other trial (three participants only with primary Raynaud's phenomenon) reported a median severity score of 2 on both nicardipine and placebo treatment (P > 0.999). Participant-preference scores were included in four trials, but in only two were results specific to participants with primary Raynaud's phenomenon, and scoring systems differed between trials: scores differed between treatments in only one trial, in which 33% of participants on placebo and 73% on nifedipine reported improvement in symptoms (P < 0.001). Physiological measurements were included as outcome measures in five trials (different methodologies were used in each): in none of these trials were any statistically significant between-treatment group differences found. Treatment with calcium channel blockers appeared to be associated with a number of adverse reactions, including headaches, flushing and oedema (swelling). AUTHORS' CONCLUSIONS: The randomised controlled trials included in this review provide moderate-quality evidence that oral calcium channel blockers are minimally effective in the treatment of primary Raynaud's phenomenon as measured by the frequency of attacks. However, the results of this review were limited by small sample sizes in the included studies and by variable data quality, particularly with regard to outcome measures.