Why Men Don’t Iron: The New Reality of Gender Differences. Anne Moir
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consumes less than 70% of the RDA there is cause for concern.49 Yet a survey of older Americans discovered that 40% of them, both men and women, were falling below this critical level for zinc ingestion. A high proportion of the men also failed to reach the critical level for consumption of Vitamin A.50 There is a common belief that Vitamin A can be obtained from dark-green leafy vegetables, but even spinach, comparatively high though it is in Vitamin A, still falls far below the levels available from foods of animal origin.51
Men need 45% more zinc in their diet than women (unless pregnant or breast-feeding). He needs more zinc because its essential for making androgens – the male hormones that he has ten times more of than her. But where is he going to find that zinc? The problem is compounded because the body’s store of zinc is negligible. We do store some, but most of it is in our bone and skeletal muscle and is difficult to release. Typically, only one-thousandth of our zinc is found circulating in the plasma (from where it can be taken up and put to use), so there is no ‘store’ of zinc in the conventional sense.52 Fortunately it usually takes many months for a diet low in zinc to result in any deficiency,53 but research presented to the Nordic Symposium on Trace Elements in Human Health and Disease in Norway, in 1994, warned that ‘subtle deleterious changes seem to occur at much lower zinc intakes than was previously thought.’
The USA’s officially recommended dietary intake for zinc is based on a semi-vegetarian diet. Yet if there is an adequate amount of meat in the diet, the level of zinc-rich foods you need to eat is far lower, because the zinc in meat is much more easily absorbed by the body than the zinc in unrefined cereals. There is a good reason. Unrefined cereals contain a substance called phytic acid.54 Wholemeal bread, an obvious example, is phytate rich. Phytates, or phytic acids, block the uptake of both iron and zinc. The speaker at the Nordic conference found that ‘from diets with a high content of phytate, less than 15% is typically absorbed while in refined animal protein-based diets up to 40% is absorbed.’55
‘What if some readers think that they haven’t enough of some mineral and go and buy iron pills or whatever to boost their intake?’ asks Bill
‘Too much zinc cuts iron in the blood,’ Anne replies, ‘causing an anaemia that won’t go away with iron supplements. But at least on a balanced diet you won’t overdose.’
‘And vegetarians?’
‘Better consult a sensible doctor.’
Male deficiencies, red meat and phytates
Back to the Arkansas study. If there were enough meat in the diet then men’s zinc deficiency would soon be solved, yet by adding more whole grains to the diet, which is what the nutritionists recommended, the overall availability of zinc might actually decrease owing to the action of the phytates in the unrefined cereals.
‘What’s going on?’ asks Bill. ‘Bran, oats, fibre-rich cereals … horse food.’
‘Health food,’ says Anne.
‘The phytates in them are zinc zappers. And they slurp up the iron the gut would otherwise take in.’
‘Unhealthy health food, then.’
Men need a ready, steady supply of zinc in their diet because a lack of it impairs the metabolism of androgens which are the essential male hormones.56 And where is zinc most readily found? In red meat. Not in white flesh. A lean piece of beef has six times as much zinc as chicken breast and ten times more than in fish.57 Wholemeal wheat may have almost as much zinc as the beef, but the phytates in the wholemeal block the zinc uptake. Phytates also bind with iron and calcium, two other essential micronutrients, and so prevent their absorption. Phytates are undesirable, but the protein in red meat acts as an anti-phytate agent.
This was well known by the mid-1980s,58 but somehow red meat has become demonized, even though research has shown that young males brought up on a diet low in meat and heavy on wholemeal bread and unrefined cereals, as is common in some poor countries, experience a high proportion of growth defects. An example is the epidemic of rickets that occurred among the children of Dublin in the 1940s. The Irish Republic, though neutral in the war against Hitler, had been forced to impose rationing and the main bread in Dublin was whole-grain. The combination of the phytates in the bran – which removed the calcium from the diet – and too little Vitamin D, resulted in an epidemic of rickets and after three years of rationing nearly half the children in the city were suffering.59
In Scotland the consumption of wholemeal bread has tripled since 1980. Women are mostly responsible for the increase and, unsurprisingly, a report on Scottish eating habits finds this trend ‘healthy’, while the males who continue to eat white bread are condemned as displaying a pattern of ‘unhealthy eating’. This judgement ignores the realities. Wholemeal bread does contain more vitamins and minerals than refined white bread, but much of that goodness is locked into the bran, which is indigestible. Unrefined flour also retains its outer aleurone layer which contains the undesirable phytates. Nutrients in white bread flour, though fewer because the germ and aleurone layers have been removed, are spared the effects of the phytates and so more of those nutrients are absorbed by the body. Additionally, because white bread is thought less wholesome, the nutrients are artificially added. Wholemeal flour, because it is deemed ‘natural’, is left unfortified.60 The Scottish men also ate a seventh more red meat than their womenfolk, and this too was deemed to be ‘unhealthy’, though the researchers made no effort to distinguish between lean or fat meats, just as they appeared ignorant of the deleterious effects of phytates in wholemeal bread.61 Such is the current health-food wisdom: red meat unhealthy, white bread unhealthy – men are unhealthy.
‘The label on my wholemeal bread tells me that it’s full of goodness,’ Anne says.
‘What it doesn’t say is how it’s full of phytates blocking out that goodness,’ says Bill, ‘nor how the fibre in the bran speeds food through the gut and so acts as a mild laxative.’
‘Truly,’ said Anne, ‘wholegrain bread is one of the original fast foods. The good news is that it shouldn’t harm you if the rest of your diet is healthy.’
But what is thought to be healthy might very well not be. Current dietary recommendations do not take into account the poor bioavailability of minerals in the high-fibre diet so often associated with health food which, in its composition, is very like a Third World diet. They also overestimate the amounts of protein and energy that are available in such diets because too much fibre is assumed to be digestible.62 In rural Mexico anaemia is found in a third of men and pregnant women and in over half of non-pregnant women. ‘Low meat intake and poor dietary iron bioavailability were associated with anaemia in women.’63
‘Health food …’ says Bill. ‘I guess by definition all else is unhealthy: get-sick-and-die-quick food.
‘Here’s the definition in my Collins Concise Dictionary,’ says Anne. “‘Health food n. vegetarian food organically grown and with no additives, eaten for its benefits to health”.’
‘Eaten with a cupboard full of artificial vitamin supplements from the health food store? Yet many a vegetarian lives long.’
‘Life outside the fast lane,’ said Anne. ‘Slow laps in the pool, aerobics and yoga: less risk and competition – more female than male. It’s not so much a lack of meat that makes for this long life, more a damped-down lifestyle. On the evidence to date, if the nice health-food people ate some nice red meat they’d live an even longer life. And be healthier too.’
Would nice-health food people be healthier if they overcame their repugnance for red meat? A diet containing varying amounts of lean ground beef was fed to young women by researchers in the Department of Home Economics at Illinois State University. For the first seven days all ate vegetarian. For the next three weeks they ate 3, 6, or 9 ounces of beef each day. Bodily iron increased the moment beef was introduced to the diet. Three ounces (85 grams) of beef a day was found to be the ideal amount, for there was no marked increase in the amount