What the scientists are saying…
Boxers vs. briefs
If you’re a man trying for a baby, think carefully about your choice of underwear. A study has confirmed that men who prefer boxer shorts have higher sperm counts than Y-front wearers: because tightfitting underwear can raise the scrotum’s temperature, scientists have long suspected that it affects sperm production. For the Harvard University study, researchers quizzed more than 650 men attending a fertility clinic about their preferred choice of underwear; 345 said they mainly wore boxer shorts, while 311 said they favoured tighter briefs. The team then analysed the men’s sperm, taking into account factors such as age, whether they smoked, and whether they often used saunas or hot tubs. On average, the boxer short-wearers had a 17% higher sperm count and a 25% higher sperm concentration (a measure of quality) than the brief-wearers. The latter group also had raised levels of a hormone known to modulate sperm production – suggesting their bodies were trying to restore normal production. None of the men studied had clinically low sperm counts, but the team believes that for men whose sperm is already depleted, switching to boxer shorts could make a crucial difference. “Since most men have no idea what their sperm count is, if you’re trying for a baby it’s not such a bad idea,” said Dr Jorge Chavarro, one of the researchers.
Head injuries and suicide
People who suffer traumatic head injuries may be twice as likely to commit suicide as those who haven’t, scientists have suggested. The study looked at data on more than 7.4 million people living in Denmark from 1980 to 2014, of whom 34,529 died by suicide. Among those with no history of traumatic brain injury (TBI), the suicide rate was 20 per 100,000 people per year; among those who had suffered TBIS, it was 41 per 100,000 per year. The researchers aren’t sure what accounts for this, but one possibility is that certain traits – such as impulsiveness and a tendency to suffer from mood swings – predispose people to both head injuries and suicide. But the team also suspects that TBIS are themselves causal factors. “Head trauma can affect the brain’s functions, which can cause psychological problems and, consequently, increase the risk of suicide,” said lead study author Dr Trine Madsen, of the Danish Research Institute for Suicide Prevention in Copenhagen.
Is salt less risky than claimed?
Guidelines for salt intake should be rethought, claims a controversial study, as most people consume more than the recommended daily maximum without adverse consequences. The NHS says that eating more than 6g of salt per day increases an adult’s risk of heart disease and stroke. But a Lancet-published study, which looked at data on 94,000 people in 18 countries, found no evidence of harm when up to double this amount is consumed. Only in parts of China where soy sauce is extensively used were salty diets associated with higher blood pressure and a greater number of strokes. The research also suggests that a very low-salt diet can also be harmful. “Our study adds to growing evidence to suggest that, at moderate intake, sodium may have a beneficial role in cardiovascular health, but a potentially more harmful role when intake is very high or very low,” said Andrew Mente of Mcmaster University, Ontario. Yet the study was challenged by other scientists, who criticised its methodology, saying it relied on inaccurate measurements for sodium in people’s urine.
Pollution and prams
Low-slung buggies increase babies’ exposure to pollution by placing them at the same level as car exhausts, says The Times. An analysis by the University of Surrey found that toddlers in buggies are typically exposed to 60% more pollution than those pushing them. Previous studies have found that persistent exposure to particulate pollution, of the kind produced by diesel cars, can damage the brain’s frontal lobe, affecting neurological development. Small children are thought to be especially vulnerable, because pollutants are proportionally bigger for their lungs and blood vessels. The researchers urged parents to consider “mitigating action”, including taking quieter routes and avoiding rush-hour traffic.