A life without heart disease - fat chance

This is a detective story, as complicated and with as many twists and turns as an Agatha Christie whodunnit. The killer is the architect of the epidemic rise in heart disease over the past 100 years - 6 million a year at the last count and well on the way to becoming a 21st-century scourge of biblical proportions. The usual suspects are cholesterol, a diet high in animal fat, salt, obesity, a sedentary life, smoking and stress. But we have all been on the wrong trail, as David Barker demonstrates with elegant logic in this magnificent book.

To those of us who bought into the story of bad cholesterol/animal fat as a cause of heart disease, inconsistencies have always niggled; for instance, a direct link between how much fat a person eats and their risk of heart disease has proved difficult to establish, and altering people's diets only modestly reduces their cholesterol levels.

Instead, it turns out that the real villain is your mother! Your mother bequeaths to you the first external environment you have to grapple with - her womb - and, according to Barker's irresistible thesis, while the fine-tuning of metabolism made in utero to cope with adversity is appropriate for a developing foetus, it is dynamite once it has grown up.

The fuse lit by undernutrition in the womb explodes decades later as heart disease, high blood pressure, stroke and diabetes. It is not your genes.

There are no genes for heart disease. It is down to compromised food supply.

This twist - that heart disease starts in the womb - emerged when Barker was studying the demography of heart disease and struggling with the paradox that this disease of affluence sought out the poorest, worst-nourished communities - that also have to live with the worst death toll in newborns. In a leap of imagination, Barker overlaid a map of the heart-attack capitals of England and Wales with a map of the blackspots for low-birthweight babies. They matched. He concluded that people who were small at birth (under 6lbs) were candidates for heart disease and, as his determined sleuthing confirmed, much else besides.

It is well known that people who get heart disease have high blood pressure, too much cholesterol in their blood and are less able to store sugar in their muscles, which eventually leads to diabetes. What is less well known is that these people, by and large, have incubated these deficiencies since childhood.

How do some of us get stuck on that track? Let us return to that undernourished, low-weight baby. If mum herself is undernourished, working too hard, or the placenta is below par, the developing foetus makes the best of a bad job: it keeps its blood sugar high (the cardinal feature of diabetes) to nourish the brain and heart. The liver, meanwhile, concentrates on developing those parts that elevate blood sugar but, in a trade-off, sacrifices those parts that lower cholesterol. Aha!

The kidneys also take a hit to preserve the brain and at birth have three times fewer filtration units than a well-nourished baby. After a lifetime of wear and tear, there are too few kidney cells left to keep blood pressure normal. Similarly, the undernourished baby lacks muscle mass, the body's essential sugar reservoir, so is deaf to signals from insulin to lower its blood sugar. Bingo - it is a small step to diabetes, especially if you couple inactivity with eating high-calorie food.

Those set points acquired in the womb cannot be shifted by fattening up skinny babies. Uterine undernourishment hardwires the structure and function of body systems. They are preserved for a lifetime. Paradoxically, fattening the child is the worst thing you can do. Barker's denouement is that the costs are attached to an initial phase of slow growth followed by rapid weight gain, some of which are immediate (disturbed bone growth) and some deferred (heart disease and diabetes).

The "adiposity rebound", if it happens between three and six years of age, is a prognosticator of poor health later. These children go on to become the fattest by about the age of eight and are on the slippery slope to adult obesity.

Fortunately, Barker explains the paradigms for maternal and infant nutrition to avoid these pitfalls. Women wanting to bear healthy children have to start eating a varied, balanced diet long before they conceive. And for infants, Barker has a few golden rules: do not introduce solids before six months; do not give pureed fruit and vegetables as the only first weaning food - too few calories and too little fat; after six months give follow-on formula and iron-rich foods. The blurb says all prospective parents must read this book. I only hope they will.

Miriam Stoppard is a writer and broadcaster.