Iodine status of consumers of milk-alternative drinks v. cows' milk: data from the UK National Diet and Nutrition Survey.

Milk is the main source of iodine in the UK; however, the consumption and popularity of plant-based milk-alternative drinks are increasing. Consumers may be at risk of iodine deficiency as, unless fortified, milk alternatives have a low iodine concentration. We therefore aimed to compare the iodine intake and status of milk-alternative consumers with that of cows' milk consumers. We used data from the UK National Diet and Nutrition Survey from years 7 to 9 (2014-2017; before a few manufacturers fortified their milk-alternative drinks with iodine). Data from 4-d food diaries were used to identify consumers of milk-alternative drinks and cows' milk, along with the estimation of their iodine intake (µg/d) (available for n 3976 adults and children ≥1·5 years). Iodine status was based on urinary iodine concentration (UIC, µg/l) from spot-urine samples (available for n 2845 adults and children ≥4 years). Milk-alternative drinks were consumed by 4·6 % (n 185; n 88 consumed these drinks exclusively). Iodine intake was significantly lower in exclusive consumers of milk alternatives than cows' milk consumers (94 v. 129 µg/d; P < 0·001). Exclusive consumers of milk alternatives also had a lower median UIC than cows' milk consumers (79 v. 132 µg/l; P < 0·001) and were classified as iodine deficient by the WHO criterion (median UIC < 100 µg/l), whereas cows' milk consumers were iodine sufficient. These data show that consumers of unfortified milk-alternative drinks are at risk of iodine deficiency. As a greater number of people consume milk-alternative drinks, it is important that these products are fortified appropriately to provide a similar iodine content to that of cows' milk.

Selenium status and blood lipids: the cardiovascular risk in Young Finns study.

BACKGROUND: Concern has been recently raised about possible adverse cardio-metabolic effects of high selenium status, such as increased risks of diabetes and hyperlipidaemia. However, most of the evidence comes from selenium-replete populations such as that of the United States. OBJECTIVES: To examine cross-sectional and longitudinal associations of serum selenium with cardiovascular risk factors in Finland where selenium levels were amongst the lowest in the world until the early 1980s before the implementation of a nationwide selenium fertilization programme. METHODS: Serum selenium was measured in 1235 young Finns aged 3-18 years at baseline in 1980 (prefertilization) and in a subgroup (N = 262) at the 6-year follow-up (1986, postfertilization). During the 27-year follow-up, serum lipids, blood pressure, body mass index and smoking were assessed five times (1980, 1983, 1986, 2001 and 2007). RESULTS: Mean (±SD) serum selenium concentrations were 74.3 ± 14.0 ng mL(-1) in 1980 and 106.6 ± 12.5 ng mL(-1) in 1986 (average increase 32.3 ng mL(-1); 95% CI: 30.3 to 34.3, P < 0.0001). In univariate and multivariable cross-sectional models in 1980 and 1986, increased serum selenium levels were consistently associated with increased total, HDL and Low-density lipoprotein (LDL) cholesterol. However, the average longitudinal changes in lipids were -0.20 mmol L(-1) (95% CI: -0.30 to -0.10, P < 0.0001) for total cholesterol, 0.06 mmol L(-1) (95% CI: 0.03 to 0.10, P < 0.0001) for HDL cholesterol, and -0.23 mmol L(-1) (95% CI: -0.31 to -0.14, P < 0.0001) for LDL cholesterol. Selenium measured in 1986 was not associated with lipids assessed in 2001 and 2007. CONCLUSIONS: Cross-sectional findings from the Young Finns study corroborate positive associations of selenium status with serum lipids. However, longitudinal evidence does not support the causality of this link.

Selenium status and cardiometabolic health: state of the evidence.

Use of selenium enriched foods, supplements and fertilizers has increased markedly in recent years in the US and other Western countries because of the perception that the anti-oxidant properties of selenium could potentially reduce the risk of cancer and other chronic diseases. However, concern has been raised recently about possible adverse cardiometabolic effects of high selenium exposure, including an increased risk of diabetes and hyperlipidemia with high selenium intake. Hence, from a public health perspective, the relationship between selenium status and cardiometabolic health should be clarified in order to help guide consumers in their choices of nutritional supplements and enriched food products. Additional experimental evidence is needed to provide new insights into the role of selenium and of specific selenoproteins in human biology, especially to clarify the underlying mechanisms linking selenium to chronic disease endpoints. Further epidemiological studies and randomized clinical trials across populations with different selenium status should be conducted to determine the causal effect of selenium on cardiovascular disease and risk factors. Nevertheless, at the present time the widespread use of selenium supplements or other strategies that artificially increase selenium status above the level required for optimal selenoprotein activity is not justified and should not be encouraged.

Selenium supplementation and premature (pre-labour) rupture of membranes: a randomised double-blind placebo-controlled trial.

The aim was to determine if selenium supplementation during pregnancy reduces the occurrence of premature (pre-labour) rupture of membranes (PROM). A total of 166 primigravid pregnant women in the first trimester of pregnancy, were randomised to receive 100 microg of selenium (n = 83, drop-outs = 22) or a placebo (n = 83, drop-outs = 19) per day until delivery. The incidence of PROM, as well as serum selenium concentrations were evaluated at baseline and at the end of the study. Supplementation with selenium was associated with a significant increase in mean serum selenium concentration at term (p < 0.001). In contrast, mean serum selenium concentration remained unchanged in the control group (p > 0.05). The incidence of PROM was significantly lower in the selenium group (n = 8, 13.1%) than in the control group (n = 22, 34.4%) (p < 0.01). Our findings indicate that selenium supplementation (100 microg/day) in pregnant women effectively reduces the incidence of PROM.

The importance of selenium to human health.

The essential trace mineral, selenium, is of fundamental importance to human health. As a constituent of selenoproteins, selenium has structural and enzymic roles, in the latter context being best-known as an antioxidant and catalyst for the production of active thyroid hormone. Selenium is needed for the proper functioning of the immune system, and appears to be a key nutrient in counteracting the development of virulence and inhibiting HIV progression to AIDS. It is required for sperm motility and may reduce the risk of miscarriage. Deficiency has been linked to adverse mood states. Findings have been equivocal in linking selenium to cardiovascular disease risk although other conditions involving oxidative stress and inflammation have shown benefits of a higher selenium status. An elevated selenium intake may be associated with reduced cancer risk. Large clinical trials are now planned to confirm or refute this hypothesis. In the context of these health effects, low or diminishing selenium status in some parts of the world, notably in some European countries, is giving cause for concern.

Comparison of selenium levels in pre-eclamptic and normal pregnancies.

Abnormal placentation is the likely cause of the slow fetal growth and the high levels of circulating lipid peroxides found in severe pre-eclampsia. These peroxides are probably responsible for the high thromboxane:prostacyclin ratio found in this disease and may participate in the endothelial cell damage which is its most notable feature. Selenium (Se), because of its role in glutathione peroxidase, is suggested to be an important component of the removal system for these damaging peroxides. Serum-Se concentrations have therefore been measured in 19 pairs of pre-eclamptic women and matched controls. Infant birth-weights were recorded. No significant difference was found in the concentrations of Se in pre-eclamptic and control groups. Serum Se was found to be low in both groups. Birthweights were significantly lower in the pre-eclamptic group. The interpretation of serum-Se measurements from the third trimester of a pre-eclamptic pregnancy is complicated by the reduced fetal growth and probable lower Se take-up by the fetus in such a pregnancy. The merits of alternative measurements, such as total intravascular Se, placental Se, or samples from an earlier stage of gestation, are discussed. The importance of factors other than Se to the activity of glutathione peroxidase, and of other antioxidants to pre-eclamptic, is stressed.