A bald head is no advantage when it comes to absorbing vitamin D from the sun, say scientists seeking an explanation for why men lose their hair.
The study, which researchers warned could be skewed by "undisclosed use of hair pieces or 'comb over' techniques", saw 296 middle-aged or older men recruited and rated according to their hair.
Skin type and how often they wore a hat or applied sunblock to their scalp were also taken into account in a bid to explain why older men commonly have higher levels of vitamin D than older women.
Almost half of the study group (48 per cent) had a full head of hair or only "mild" recession, while 15 per cent had "predominant" hair loss and 37 per cent were bald or had "significant" hair loss.
Despite the variables across the groups, researchers found there was no statistically significant difference in the men's level of vitamin D.
"We conclude that baldness does not appear to have an effect on vitamin D status," the authors state.
"... Other hypotheses are required to determine why older men go bald and whether baldness serves any physiological purpose."
The researchers said it was possible vitamin D was not produced in the scalp, and that older women had lower vitamin D levels because they had less sun exposure in general and they were more likely to use sunblock.
Baldness occurs almost universally with ageing in men, and more than 70 per cent of men older than 70 years have significant hair loss, the report states.
The study, published in the Medical Journal of Australia, was conducted by University of Auckland's Dr Mark Bolland and colleagues.
"All but one of the male authors have a full head of hair," the report disclosed.
Bald head offers no vitamin D advantage
Is this due to lack of vitamin D production in scalp or due to wearing hats to hid the loss of hair?