"I mentioned... the food-essentials... needed during pregnancy; a well-balanced diet containing 7Og/day of protein, of which one-third must be derived from animal sources; an abundance of all vitamins, including vitamin D, which, however, should be provided in the form of cod liver oil so as to avoid the risk of over-dosage and as an additional source of iodine; 2g/day of calcium; 1.6g/day of phosphorus; 0.3g/day of magnesium; and 20g/day of iron. Personally I believe that the best diet for expectant mothers is one made up of whole cereal grains, milk, milk products and eggs and with fresh green vegetable foods and fruit in abundance." Sir Robert McCarrison, 3rd Cantor Lecture to the Royal Society of Arts, 1936¹ (1 page 77).

Why is there any need for a fertility diet? A fertility diet must not only be concerned with conception but must be a diet which will maximize the chance of a baby being born of satisfactory weight and will minimize the risk of disability.

That the outcome of pregnancy could be prejudiced by particular nutrient deficiencies was first demonstrated by Hale who reported experiments in 1933 showing th.at a vitamin A deficiency around the time of mating and the very beginning of pregnancy produced piglets without eyeballs.² Since the 1930s the effects of deficiencies of other essential nutrients around the beginning of pregnancy has been studied in Europe, America and Asia. During the same decades in parallel with the work on nutrients there has been a great development of work on the effect of toxic and xenobiotic substances on sperm and ovum and zygote and embryo. One conclusion of these studies is that all mammals are particularly susceptible to an inadequate diet or biochemically hostile environment at this time.

The development of embryo, fetus and child follow a genetic programme which begins to unfold during maturation of ovum and sperm. Damage to this programme setting development on a wrong path and, in particular, deletion of parts of the programme at an early stage, cannot be remedied subsequently in most cases. A fertility diet aims to reduce the risk of damage to this genetic programme. A key question may be asked: In preparation for pregnancy are some key nutrients more important than others? If some nutrients are more important then some foods must be more important.

FIFTEEN KEY NUTRIENTS FOR PREGNANCY

Previous papers in this journal reported the results of a study of the diet of 513 women in Hackney very early in pregnancy before nutritional advice had been given.^3,4 For one half of these mothers who had the larger babies with birthweights over the median of the 3,270g there were no significant correlations of diet with birthweight. It was a reasonable inference that birthweight of the larger babies was little affected by further increases in the maternal consumption of particular nutrients or by variations in maternal diet and, indeed, that saturation levels for the individual nutrients were achieved, and that the variations in birthweight of the larger babies above median birthweight had other causes. For these mothers more food did not mean bigger babies.

TABLE 1

15 key vitamins and minerals correlated with birthweight in the diet of 255 London mothers with babies weighing below 3,270g

nutrient	correlation coefficients with birthweight	significance
	r	p
magnesium	0.253	0.001
iron	0.247	0.001
phosphorus	0.243	0.001
zinc	0.238	0.001
potassium	0.208	0.001
thiamin Bi	0.200	0.001
niacin B3	0.198	0.001
copper	0.188	0.002
pantothenic acid B5	0.186	0.002
calcium	0.184	0.002
riboflavin B2	0.183	0.002
folic acid B9	0.173	0.003
pyridoxine B6	0.168	0.004
biotin	0.149	0.006

Source: See References 3, 4 and personal communication.

However, 255 women who had smaller babies below the median birthweight of 3 ,270g had significantly lower average intakes of energy, of protein and of 15 key nutrients. In Table 1 these key nutrients are ranked by their correlation coefficients with birthweight.⁴ which are all seen to be statistically significant and positive showing that the lower the nutrient intake the greater was the apparent risk of lower birthweight. The more these mothers ate the bigger were their babies up to the median. The larger the coefficient the greater was the number of women who had both a lower birthweight and a lower consumption of the particular nutrient. This suggests for example that magnesium and iron at the top of the table may have been more important in influencing birthweight in Hackney than pyridoxine and biotin at the bottom of the table. The ranking may be different for other populations with different diets. Is there other evidence supporting the hypothesis that these 15 key nutrients influence fertility and baby size?

CLASSIC ANIMAL EXPERIMENTS ON DIET, FERTILITY AND MALFORMATIONS

The Code of the World Medical Association requires all biomedical research involving human subjects to, "be based on adequately performed laboratory and animal experimentation". Animal experimentation proves nothing about humans but establishes hypotheses. Such experimentation is required by law in all developed countries as evidence of the toxicity of chemicals. The governmental Guidelines for the Testing of Chemicals for Toxicity say:⁵

"The results of studies in animals normally form the major part of the evaluation of the safety-in-use of a chemical, as generally only few data are available for man.. . . The use of animals for toxicity testing provides the best means currently available for assessing any potential hazard for chemicals in man."

The effects of nutrient deficiencies on pregnancy outcome have been accepted much more slowly than the effects of toxic chemicals, although deficiencies have been shown to be equally damaging. Research has also shown that the teratogenicity of many chemicals is increased by low intakes of particular minerals and vitamins.⁶

TABLE 2

Classic animal studies on results of deficiencies of some nutrients around mating

nutrient	results
	low birthweight	stillbirths	malformations	reference
magnesium	yes	yes	yes	7
iron	yes	yes	no	8
zinc	yes	yes	yes	9
potassium	yes	yes	no	10
copper	yes	yes	yes	11
thiamin Bi	yes	yes	no	12
niacin B2	yes	yes	yes	13
pantothenic acid	yes	yes	yes	14, 15
riboflavin B2	yes	yes	yes	16, 17
pyridoxine B6	yes	yes	yes	18, 19
biotin	yes	?	yes	20
folic acid B9	yes	yes	yes	21, 22
cobalamin B12	yes	yes	yes	23
manganese	yes	?	yes	24
iodine	yes	yes	yes	25

The effects on the outcome of pregnancy in animals of deficiencies of the key nutrients in Table 1 have been studied and the references to classic papers are listed in Table 2.^7-25 Systematic research at the University of California led by Marjorie Nelson and Herbert Evans was reported from 1946 to 1956 and research in Paris led by Antoinette Giroud and colleagues from 1947 to 1961. The research was continued at the University of California into the 1 990s by the late Lucille Hurley and colleagues. Cobalamin B 12, iodine and manganese, not in Table 1, have been added in Table 2, and no suitable references have however been found for the key nutrients phosphorus and calcium which appear in Table 1. It is seen in Table 2 that the animal experiments support the hypothesis that the correlation of birthweight with nutrient intake in Table 1 is a result of the variations in intake of one or more of the key nutrients in the diet of the Hackney women. The hypothesis is also supported by a substantial veterinary literature.

This hypothesis is supported by more recent animal studies on the causes of intrauterine growth retardation. For example a team at the US National Classic animal studies on results of deficiencies of some key nutrients around mating results nutrient low birthweight stillbirths malformations reference Institutes of Health's laboratory for Child Health and Human Development reported in 1985 on experimental production of low birthweight in animals by thiamin deficiency.²⁶ Thiamin is only one of the key nutrients essential for the transfer of energy.

ENERGY TRANSFER NUTRIENTS IN THE FERTILITY DIET

Energy in the right form and in adequate concentration is needed for cell replication and therefore at all stages of reproduction. Several of the key nutrients in Table 1, namely thiamin, riboflavin, niacin, magnesium, phosphorus and iron are mainly concerned with energy transfer and are therefore called the energy transfer nutrients. For most purposes the special carrier for free energy at the point of use is adenosine triphosphate (ATP). ATP has been called, "the main fuel of life" and the "universal currency of free energy in biological systems".²⁷ ATP is the immediate donor of free energy essential for biosynthesis, cell replication and growth, and is continually formed and consumed.

Carbohydrates and fats which are the main sources of energy in our diet must be oxidized to make the energy available and be transferred to ATP for local use, whether to provide muscular effort or build new tissue. The energy transfer from food to ATP requires several of the key nutrients in Table 1. Phosphorus, a major constituent of ATP, is seen to hold third place in Table with maternal intake highly correlated with birthweight. The active form of ATP is usually in a complex with magnesium ion; magnesium heads the key nutrients in Table 1. Thiamin B 1 is concerned with the oxidation of sugars and riboflavin B2 with oxidation of fats. A slow-down of ATP turnover slows down cell replication, growth and development. The hypothesis follows that low birthweight is partly caused by a deficiency of one or more of the energy transfer nutrients. The hypothesis is supported by the prominence of the energy transfer nutrients in Table 1 based on the Hackney studies.

Energy is required for the synthesis of all the large molecules needed in the construction of new cells at all stages of reproduction in all animals and plants. It is not therefore surprising to find the energy transfer nutrients concentrated in germinal tissue including eggs and sperm, seeds and nuts. Such reproductive tissue makes a major contribution to human diet as cereals and cereal products, cauliflower and broccoli, fruit and nuts. Animals contribute eggs and fish roe. Table 3 shows the concentration of nutrients in wheat germ and Table 4 the concentration of the same nutrients in egg yolk.²⁸

The energy transfer nutrients are not only concentrated in germ cells and in reproductive tissue but in other tissues with high energy demands which include the heart, brain, liver and kidneys with substantially higher concentrations than in muscle-meat. Tables 3 and 4 show also nutrients concentrated in reproductive tissue which are not energy transfer nutrients, notably folic acid and zinc, which are required in higher concentrations for the

TABLE 3

Breadmaking white flour and wheat germ; micronutrient/protein ratios compared

nutrient	white flour	wheat germ
	a	b	b/a
	mg/ 100g protein
biotin	0.009	0.094	10.4
riboflavin B2	0.26	2.7	10.4
pyridoxine B6	1.3	12.4	9.5
zinc	7.83	63.7	8.1
manganese	6.1	46.1	7.6
folic acid B9	0.27	1.24	4.6
phosphorus	1,043	3,933	3.8
magnesium	270	1,011	3.8
potassium	1,130	3,558	3.1
thiamin Bi	2.8	7.5	2.7
pantothenic acid B5	2.6	7.1	2.7
copper	1.57	3.37	2.1
iron	18.3	31.8	1.7
calcium	1,217	206.0	0.2

Source: See Reference 28.

TABLE 4

Chicken breast and egg yolk; micronutrient/protein ratios compared

nutrient	chicken breast	egg yolk
	a	b	b/a
	mg/100g protein
biotin	0.01	0.31	31.0
calcium	46.0	807.0	17.5
iron	2.3	38.0	16.5
folic acid B9	0.055	0.807	14.7
zinc	3.2	24.0	7.5
riboflavin B2	0.4	63.35	7.3
pantothenic acid B5	5.5	28.6	5.2
thiamin BI	0.46	1.86	4.1
phosphorus	963.0	3,110.0	3.2
copper	0.64	0.93	1.5
sulphur	962.00	1,055.0	1.1
pyridoxine B6	2.43	1.86	0.8
magnesium	123,0	93.0	0.8
potassium	1,510.0	751.0	0.5

Source: See Reference 28

synthesis of the DNA of the nucleus of new cells and are not, for example, similarly concentrated in the heart, which has a high demand for the energy transfer nutrients but not for folic acid and zinc. A fertility diet requires an adequate intake of magnesium, iron and phosphorus and the B vitamins, all concerned with energy transfer, but also of zinc and folic acid for which there are special requirements for reproduction. The reproductive tissues of plants and animals are rich sources of the key nutrients in Table 1.

THE STORY OF THE FERTILITY LOAF

Our understanding of the key role of ATP and DNA in the reproduction of all living things only dates f111rom the 1940s. That wheatgerm helped to promote the fertility of farm animals and horses had long been believed in farming communities and racing stables, and spread to a belief in the value for women. In the 1 930s married women in Holmes Chapel in Cheshire knew that their local baker could provide them with "fertility bread" in the form of a "fertility loaf".²⁹ This fertility bread had two main ingredients 65 per cent wholewheat and 35 per cent wheatgerm, sacked off the rollers in a Liverpool mill. The fertility loaf was popular with married women throughout Cheshire. Wartime regulations stopped production. The wholewheat loaf and the loaf enriched with wheatgerm must be part of our fertility diet.

A STORY OF FISH AND FERTILITY

Fish eggs as a food have a long history of association with the fertility of men and women. In his study of the diets of the indigenous peoples of South America Weston Price reported that natives of Peru30 (pages 265, 40 1973):

"Used fish eggs liberally during the developmental period of girls in order that they might perfect their physical preparation for the later responsibility of motherhood. These fish eggs were an important part of nutrition of the women during their reproductive period. They were available both at the coast markets of Peru and as dried fish eggs in the highland markets, whence they were obtained by the women in the high sierras to reinforce their fertility and efficiency of childbearing."

The energy transfer nutrients are even more concentrated in fish eggs than in the yolk of a hen's egg. 28 Thus cod's roe is reported to have 5.6 times as much thiamin as cod fillets, 4.5 times as much iron, and so on for other nutrients concentrated in germinal tissue. Iodine is another nutrient essential for reproduction, and Weston Price thought that part of the value of the fish eggs was in the iodine they contained.

THE RNIs DO NOT DESCRIBE A FERTILITY DIET

The New York Academy of Sciences called a conference in 1992 entitled, "Maternal Nutrition and Pregnancy Outcome". The editorial summary on the implications of the conference for public policy began³¹ (page 284):

"A major area of consensus of this conference was that prepregnancy nutritional status significantly affects pregnancy outcome."

The Reference Nutrient Intakes (RNIs) of the British Departments of Health do not recognize any special nutritional needs of women planning pregnancy and only some very small additions to the RNIs for women who are pregnant³² The RNIs for minerals and B vitamins are compared in Table 5 with the median intake of women aged 25 to 34, from The Dietary and Nutritional Survey of British Adults showing that there is an implied recommendation that women should eat less of the key nutrients.³³ It is also seen that the intakes of mothers who had babies of optimum birthweight were similar to the intake of non-pregnant women but higher for iron, zinc, phosphorus and copper. Even the mothers of low birthweight babies had nutrient intakes higher than the RNIs which do not take the measure of the needs of pregnancy. The RNIs recommend additions for pregnancy of only 3 of the key nutrients in Table 1.

TABLE 5

Mothers' intake of nutrients by baby weight compared to intake of non-pregnant women and to RNIs

nutrient	baby weight*		RNI	adult survey
	optimum	low	women 19-50	women 25-34
protein g/day	73.2	64.5	45	57.8
	median mg/day
mg/day thiamin	1.20	0.94	0.8	1,57
riboflavin B2	1.86	1.41	1.1	1.95
niacin B3	31.3	26.1	13.0	27.3
pantothenic acid B5	4.25	3.64	na	4.5
pyridoxine B6	1.45	1.19	1.2	1.53
magnesium	260	203	270	225
iron	11.8	9.82	14.8	9.6
zinc	9.93	8.45	7.0	7.8
phosphorus	1,286	1,055	550	1,017
copper	1.53	1.17	1.2	1.08

*optimum weight 3,500-4,500g; low weight 2,500g or less

Sources: See References 4, 32, 33.

WOMEN EAT MORE IN PREGNANCY

Appetite in pregnancy increases under hormonal influence notably of progesterone. Women's appetite begins to increase already during the latter half of the menstrual cycle, the luteal phase, under hormonal influence and continues to increase in the event of fertilization.^34,35

Table 6 compares nutrient intakes of American women neither pregnant nor lactating with intakes of pregnant women. It is likely that some of the women in the first column were amenorrhoeic, or not well enough fed to be fertile³⁶ (pages 371-408). The actual nutritional costs of pregnancy are higher than often accepted and are underestimated in social security benefits.

WHAT SHOULD BE THE DAILY PROTEIN INTAKE IN A FERTILITY DIET?

Maternal protein intake at the beginning of pregnancy is found in nutrition surveys to be an important correlate of subsequent baby length and weight. The recorded protein intake of the mothers who had babies of satisfactory size is a logical basis of recommendation.

The average daily protein intake of women during pregnancy recorded in 15 different surveys is shown in Figure 1.³⁷ Point no [1] on Figure 1 is for the 165 Hackney women who had babies in the 3,500 to 4,500g birthweight bracket.4 Their daily protein intake had a mean value of 73g and a mean energy intake of 1,983 kcal. Only point no [12] for Navajo Indians is seen to show a percentage of energy from protein below 14. Point no [7] with the highest protein intake of 110g/day was American adolescents of mixed ethnic background and high energy consumption. Point no [5] with the lowest energy consumption was for American women all over 35 of mixed ethnic background.

Protein intake is in practice much influenced by energy intake and Figure 1 suggests that any recommendation is best expressed as a percentage of energy derived from protein rather than in terms of daily protein intake. The British Hackney survey recorded a percentage of 14.7 and the American survey suggest that 15 per cent of energy from protein is a sensible recommendation for pregnancy. It is seen at the foot of Figure 1, that the RNI for protein and the resulting percentage of energy from protein are much lower than found in any of these surveys.

TABLE 6

Nutrient intakes of non-pregnant and pregnant women: mean of intakes, American women aged 19 to 39

nutrient	neither pregnant nor lactating	pregnant
	intake per day		%
	a	b	b/a
energy kcal	1,629	1,947	120
protein g	64	76	120
vitamin C mg	83	102	123
thiamin Bi mg	1.12	1.35	121
riboflavin B2 mg	1.40	1.94	139
pyridoxine B6 mg	1.25	1.60	128
folic acid B9 mcg	209	263	126
cobalamin B12 mcg	4.5	6.2	138
calcium mg	637	963	151
phosphorus mg	1,023	1,330	130
magnesium mg	217	263	121
zinc mg	9.2	11.0	120
iron mg	10.9	12.9	118

Source: See Reference 36

Table 6 shows that women during pregnancy consumed 76g/day protein, 12g/day more than women who were not pregnant. The RNI for pregnancy is 51g/day which is 6g/day higher than for women not pregnant. The Department of Health's book on Dietary Reference Values says that the extra protein allowance recommended for pregnancy of 6g/day was calculated to allow for protein retention in the products of conception and in the maternal tissues associated with the birth of a 3.3kg infant.32 Hytten and Leitch's book on the physiology of pregnancy shows the protein added in a normal pregnancy of 40 weeks' gestation as 925g for a 3.4kg infant.³⁸ Using this figure the 6g/day extra protein would have to be utilized throughout pregnancy at an efficiency of 55 per cent beginning immediately after conception in order to produce 925 g. Fifty-five per cent is much higher than the average efficiency of dietary protein utilization. Figure 2 shows the results of a study by Professor Galloway and colleagues of the University of California of the nitrogen intake and nitrogen balance of pregnant women. The slope of the regression line gives the efficiency of nitrogen utilization which was 26 per cent in this study not 55 per cent.³⁹

At the RNI of 51g/day for women during pregnancy the regression line is close to zero nitrogen balance, suggesting that in the average case the RNI of 51g/day would not support a pregnancy at all. Gontzea's textbook on nutrition in pregnancy advised that averaging the results of studies of pregnant women showed that a daily protein intake below 56g produced a slightly negative nitrogen balance, the result of 52 per cent of days in which the balance was negative and 48 days with a positive balance.40 The percentage of days with a negative nitrogen balance was found to decline steeply as daily protein intake increased up to 85g. Average nitrogen retention is seen also in Figure 2 to increase with nitrogen intake to protein intakes above 85g/day.

The efficiency of protein utilization in practice varies over a wide range from negative to positive values and depends upon the intake of other nutrients essential for protein utilization. Deficiencies of magnesium or thiamin, for example, can cause nitrogen balance to be negative as can also a deficiency of energy intake. The efficiency of protein utilization and an adequate nitrogen balance depend, indeed, absolutely on an adequate intake of our key nutrients in Table 1.

PROTEIN'S FELLOW TRAVELLERS

As shown, for example, in Tables 3 and 4 the key nutrients are always found in reproductive tissue in association with protein which facilitates subsequent growth. The correlates of protein with the key nutrients from the Hackney survey are shown in Table 7. Protein is always found in foods in association with other nutrients which have been called "protein's fellow travellers". These fellow travellers are the same as the key nutrients for reproduction in Table I. It is difficult in practice to reduce protein consumption without reducing the intake of the key nutrients, protein's fellow travellers, at the same time. Observance of the current RNI for pregnancy of 51g/day, a fignre much below women s current average consumption, would inevitably involve in practice a reduction in the intake of fellow travellers or key nutrients too. Protein is not an independent dietary variable that can be easily manipulated independently of the key nutrients.

TABLE 7

Protein's fellow travellers; correlates of protein with vitamins and minerals in diet of 513 London women

nutrient	correlation coefficient
sulphur	0.918
phosphorus	0.864
zinc	0.836
pantothenic acid B5	0.792
potassium	0.741
thiamin Bl	0.731
niacin B3	0.718
riboflavin B2	0.700
calcium	0.698
pyridoxine B6	0.649
magnesium	0.646
biotin	0.622
folic acid B9	0.547
copper	0.486
iron	0.484

Source: See Reference 3 and personal communication.

The Department of Health's book says that all its recommendations for particular components of diet presuppose that, "requirements for energy and all other nutrients are met³² (page 9). This implies in the case of protein in pregnancy that protein intake is assumed to be the only factor limiting growth in the calculations underlying the RNI for protein. The scatter of the points in Fignre 2 shows that protein intake by pregnant women can hardly ever be the only factor limiting nitrogen balance in practice. Nitrogen balance and growth are seen in Figure 2 to increase as protein intake increases far beyond the RNI. This has substantial practical importance. The RNI is misleading because the improvement of nitrogen balance with growth may not be caused by the protein alone but by protein's correlates, the key nutrients or fellow travellers, for which the "requirements" were not met at the lower protein intake. These doubts about the methodology underlying the RNI for protein extend to the RNIs for all other nutrients.

FOOD CHOICE FOR A FERTILITY DIET

There is a minority of mothers whose intake of the key nutrients in Table 1 are too low. What is it, then, that these mothers eat too little or too much of? Answers to this question are available for the Hackney women by comparing the diets of the mothers of low birthweight babies with the diets of mothers who had babies in the optimum birthweight bracket of 3,500g to 4,500g. whom we call the reference mothers.

The comparative importance of different foods may be conveniently expressed as a percentage of the total energy intake difference between the two groups of mothers. The reference mothers generally had the higher intake of most foods so that the average daily differences per mother was positive at 284 kilocalories.

Dairy produce was responsible for 26 per cent of the difference in diet. The value of milk as a source of many key nutrients or fellow travellers is shown in Table 8. Cheese is an equally good source of the key minerals, but a substantial part of the B group of vitamins is lost in cheese making. McCarrison listed the "food essentials of the prospective mother in order of precedence" and gave first place to:⁴¹

"(1) Milk and the products of milk (butter, cheese, skimmed milk, buttermilk)."

A further 25 per cent of the difference in diet between the reference mothers and the mothers of low birthweight babies was attributable to breakfast cereals, which included packaged cereals, oats, muesli, nuts and seeds. Many packaged cereals are reinforced with B vitamins and iron, which will have contributed to the diet of the Hackney women. The high key nutrient content of seeds and grains was illustrated in Table 3. McCarrison gave second place in his order of precedence for the prospective mother to, "Whole or lightly milled cereal grains, in particular a good wholemeal bread and oatmeal". Wholemeal bread accounted for 7 per cent of the difference in diet between the mothers of low birthweight babies and the reference mothers in Hackney the reference mothers also ate less white bread.

Twenty one per cent of the difference in diet between the two groups of mothers was attributable to vegetables including potatoes. This 21 per cent would have been 28 per cent if it had not been for the chipped potatoes eaten in substantially larger quantity by the mothers of low birthweight babies and contributing minus 7 per cent. Retail fried chips are an impoverished food containing only 20 per cent of the thiamin found in baked potatoes including skins, and only half the minerals of baked potatoes. McCarrison gave third place to, "Green and leafy vegetables", and fourth place to, "Root vegetables, particularly potatoes, carrots and onions".

McCarrison's first 4 priorities covered 79 per cent of the actual difference in the diets between the Hackney reference mothers and the mothers of the low birthweight babies. "Fruit, including the tomato" was McCarrison's pnonty number 5 bringing the correspondence to 85 per cent. "Eggs" were McCarrison's priority number 7 increasing the correspondence to 91 per cent. Of the many other foods fish had a positive value contributing 4 per cent.

The categories of food with a negative value, showing a higher consumption by the mothers of low birthweight babies, included soft drinks, potato chips, white bread, other breads taken together e.g. malt, rye, currant, crumpets, muffins, naan, chapattis.

The consumption of meat by the mothers of the low birthweight babies was virtually the same as the consumption of the reference mothers. McCarrison gave meat his lowest priority. Meat is, of course, an excellent source of protein, zinc, iron and vitamin B12 as shown in Table 8. The absence of any significant correlation of maternal meat consumption and birthweight suggests

TABLE 8

Lean meat and milk as sources of protein's fellow travellers

nutrient	lean raw beef	whole milk
	a	b	b/a
	per 100g protein
magnesium mg	99	344	3.5
iron mg	10.3	1.88	0.18
zinc mg	21.2	12.5	0.58
phosphorus mg	887	2,875	3.2
potassium mg	1,724	4,375	2.5
thiamin Bi mg	0.34	0.94	2.8
calcium mg	34.5	3,594	104
niacin B3 mg	25.6	3.125	0.12
pantothenic acid BS mg	3.4	10.9	3.2
riboflavin B2 mg	1.2	5.3	4.4
pyridoxine B6 mg	1.6	1.88	1.2
biotin mcg	trace	59	00
folic acid mcg	49	188	3.8

Source: See Reference 28.

that the Hackney mothers had an adequate meat intake and that the mothers of the low birthweight babies were short of key nutrients, which includes protein's fellow travellers, but not pure protein. The dairy products, the breakfast cereals, the vegetables, wholemeal bread, eggs and fish provide key nutrients not available in adequate amount from muscle meat alone.

The Hackney study did not show any significant correlation of birthweight with maternal intake of vitamins A, C, D or E or with the intake of particular fatty acids. This could be explained by the adequate intake of these nutrients, as of pure protein, by Hackney women. Birthweight is also not the only measure of nutrient adequacy as discussed further below. Manganese, iodine and selenium were not recorded.

There are detailed difficulties in choosing the right food for a fertility diet to ensure an adequate intake of the key nutrients. Emphasis has been placed on the contribution of breakfast cereals, which vary however, widely, in key nutrient content and when packaged the information on the package should be read. Thus Puffed Wheat, for example, contains only very low concentrations of the B vitamins destroyed in its manufacture. However, Puffed Wheat has pride of place at the top of a coloured picture of a Plate of Good Food published by the Health Education Council in the National Food Guide.⁴²

TABLE 9

Vitamin and mineral content of some foods on the HEA Good Health Plate

nutrient	wholemeal bread	white bread	white rice	white pasta	sweetcorn in can	peaches in can
	per 1,000 kilocalories
magnesium mg	353	102	84	152	188	91
zinc mg	8.4	2.6	4.7	4.3	4.1	trace
iron mg	12.5	6.8	1.3	6.0	4.1	3.6
manganese	8.8	2.1	3.1	2.6	0.8	trace
thiamin Bl mg	1.58	0.89	1.07	0.52	0.33	0.18
riboflavin B2 mg	0.42	0.26	0.05	0.14	0.49	0.18
niacin B3 mg	19.1	7.2	11.0	8.3	12.3	10.9
pyridoxine B6 mg	0.56	0.36	0.81	0.29	1.07	0.36
folic acid B9 mcg	181	123	52	66	66	127

Source: See References 28, 42.

The mineral and vitamin B content of foods in the National Food Guide's Plate of the allegedly desirable national diet are compared in Table 9 with the composition of wholemeal bread. The white bread, white rice, macaroni, corn and fruit in cans, occupying one third of the Plate, are all foods with low key nutrient contents. In the accompanying text the desirability of wholemeal products is expressed in the small print but likely to be overlooked compared with the preference for the white flour products in the coloured illustration. The low key nutrient intake of the mothers of low birthweight babies in Table 1, is only explicable by mothers consuming too much of these foods from which the key nutrients have been removed or destroyed. The National Food Guide's Plate is misleading for women planning pregnancy. There is an implied recommendation in both the RMs and the National Food Guide that lower intakes of the key nutrients in Table 1 are desirable. The special interest of women planning pregnancy or pregnant are not recognized in either of these Government recommendations.

The National Food Guide is also short on guidance about the cost of nutrition and indeed misleading. Canned peach slices and sweetcorn are not economic sources of any nutrients, and French artichokes and asparagus are luxuries for the well-to-do.

THE CONTEXT OF A FERTILITY DIET

The fertility diet is only one important component of care before pregnancy. The importance of planning pregnancy received professional recognition in Britain in the 1970s. Geoffrey Chamberlain published an article in the British Medical Journal describing the work of his prepregnancy clinic in 1980, and a book on prepregnancy care in 1986.^43,44 A leading article in the British Medical Journal in 1981 concluded:⁴⁵

"If obstetric care is to reduce further fetal wastage and the incidence of malformation, a better understanding of the first trimester of pregnancy is vital. Only by encouraging women to attend preconception clinics.. . can we hope to improve our knowledge of and clinical management of this vital, and as yet largely ignored, period of human development."

The Health Committee of the House of Commons called for evidence on preconception services in the Session 1990-91, and produced a report and recommendations in 1991⁴⁶ In its reply the Government stated that:

"To devise specific programmes for those planning pregnancy would divert efforts and resources from the 'whole population' approach without corresponding benefits."

The report entitled, The Health of the Nation published in 1992 did not discuss prepregnancy care except for a brief mention in a chapter on HIV/ AIDS and other sexually transmitted diseases.⁴⁷ Research supported by the American Government has led to a selective approach to prepregnancy care because of the high susceptibility of women around the time of conception not only to faulty nutrition but to toxic drugs and chemicals. A paper in 1992 from the United States Environmental Protection Agency said about xenobiotics:⁴⁸

"The greatest risk to the oocyte occurs on the days just prior to ovulation."

Xenobiotics and malnutrition at this time damage the genome and interfere with genetic programming. Research centred at the Oak Ridge National Laboratory in the USA by W.M. Generoso and colleagues has shown in a series of papers since 1987 that the zygote, that is the ovum immediately after fertilization until the end of first cleavage, is highly susceptible to some mutagenic agents⁴⁹ (pages 15-16). This is not surprising considering the extraordinary complexity and speed of the events during the integration of male and female gametes. One paper refers to the exposed geometry or loose packaging of the genome at this time as conferring a unique vulnerability.⁵⁰

It is increasingly recognized that there is a comparatively short period in the whole human life cycle of greatest susceptibility to damage. It is a period entered and left before women know they are pregnant. The editorial summary of the conference of the New York Academy of Sciences in 1992 put the need for a fertility diet in its social, epidemiological and medical context³¹ (pages 285-6, our italics):

"Women at a particularly high risk for adverse pregnancy outcomes include the poor, adolescents, diabetics, substance abusers, and those with a history of previous adverse pregnancy. In each case, prepregnancy attention to nutritional issues has been shown to decrease risk of maternal and infant mortality and morbidity.On the basis of data presented at this meeting, it is clear that a critical public health policy change that should be instituted immediately is the inclusion of prepregnancy examinations as a standard medical practice for women planning pregnancy. A major component of the examination should be a nutritional evaluation.."

"Improved prepregnancy medical care, with a strong emphasis on the nutritional needs of the embryo, fetus, neonate and mother is clearly warranted. Such a public health policy would prevent a significant proportion of adverse pregnancy outcomes; the consequences include the obvious reduction in human misery as well as a significant decrease in medical expenses."

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