Effects of maternal dietary egg intake during early lactation on human milk ovalbumin concentration: a randomized controlled trial

BACKGROUND

There is limited understanding of how maternal diet affects breastmilk food allergen concentrations, and whether exposure to allergens through this route influences the development of infant oral tolerance or sensitization.

OBJECTIVE

To investigate how maternal dietary egg ingestion during early lactation influences egg protein (ovalbumin) levels detected in human breastmilk.

METHODS

In a randomized controlled trial, women were allocated to a dietary group for the first six weeks of lactation: high-egg diet (> 4 eggs per week), low-egg diet (one-three eggs per week) or an egg-free diet. Breastmilk samples were collected at 2, 4 and 6 weeks of lactation for the measurement of ovalbumin. The permeability of the mammary epithelium was assessed by measuring the breastmilk sodium : potassium ratio. Egg-specific IgE and IgG4 were measured in infant plasma at 6 weeks, and prior to the introduction of egg in solids at 16 weeks.

RESULTS

Average maternal egg ingestion was associated with breastmilk ovalbumin concentration. Specifically, for each additional egg ingested per week, there was an average 25% increase in ovalbumin concentration (95% CI: 5-48%, P = 0.01). Breastmilk ovalbumin concentrations were significantly higher in the 'high-egg' group (> 4 eggs per week) compared with the 'egg-free' group (P = 0.04). However, one-third of women had no breastmilk ovalbumin detected. No detectable associations were found between mammary epithelium permeability and breastmilk ovalbumin concentrations. Infant plasma egg-specific IgG4 levels were also positively associated with maternal egg ingestion, with an average 22% (95% CI: 3-45%) increase in infant egg-specific IgG4 levels per additional egg consumed per week (P = 0.02).

CONCLUSIONS AND CLINICAL RELEVANCE

Increased maternal egg ingestion is associated with increased breastmilk ovalbumin, and markers of immune tolerance in infants. These results highlight the potential for maternal diet to benefit infant oral tolerance development during lactation.

Observations on the ecology of Saccharosydne saccharivora (Westw.) (Hom., Delphacidae) in Jamaican sugar-cane fields

Between 1961 and 1967 intensive and extensive field studies on the sugar-cane pestSaccharosydne saccharivora(Westw.) were carried out in Jamaica (with supplementary observations from British Honduras). Egg populations were scored for size, and egg mortality and nymph-adult parasitism were estimated directly. In epidemic, but not endemic, populations, successive generations of the pest were segregated and their development was synchronised over areas of up to 80 miles2despite its 6½—7-week life-cycle and potential for continuous breeding. Segregation was due to the sterilising action of the parasiteStenocranophilus quadratus Pierce (Halictophagidae); in the drier months this spread so rapidly through the nymph and adult population that oviposition ceased until the first adults of the next generation reached maturity. In the wet season this effect was complemented by the entomogenous fungusMetarrhizium anisopliae. Synchronisation was ensured by the dispersal of parasitised adultSaccharosydne saccharivorabefore oviposition. In ratoon cane there were six or seven generations between successive annual harvests; egg populations were highest in generations 1–3 (up to 1·0×106/chain-row (≡2O·2-m row-length)), and declined in old cane irrespective of season. In plant cane, egg populations did not show a decline with age and sometimes increased. In epidemic areas a factor associated with older cane sometimes caused over 90% egg mortality; elsewhereTetrastichussp. (Eulophidae) was the leading cause of egg mortality (ca30%). Data from extensive surveys showed that the early stages of outbreaks were invariably associated with plant cane; heavy infestations rarely occurred on cane subjected to adverse growing conditions; and populations were smaller on the variety B42231 than on B4362 and B41227. Outbreak periods since the 18th century have been associated with periods of prosperity within the sugar industry, when presumably more attention was paid to improving production. Rainfall, in that it improves cane growth, is beneficial toS. saccharivora, whereas drought is detrimental; published records of outbreaks in dry periods are due to the preference of migrating adults for young cane which is most prevalent in the dry season. It is concluded that the essential prerequisite for an outbreak is plant cane growing under favourable climatic and agricultural conditions; present conditions, namely the long harvest period, high standards of cultivation, irrigation and fertiliser practice, and favourable cane varieties together offer the minimum chance for a natural end to outbreaks.

Studies on the effect of the nutrient status of sugar-cane on the fecundity of Saccharosydne saccharivora (Westw.) (Hom., Delphacidae)

An account is given of glasshouse experiments in Jamaica to determine the effects of agronomic practice on the fecundity of the sugar-cane pest Saccharosydne saccharivora (Westw.). Eggs (up to one egg per ovariole per day) develop throughout adult life. On young vigorous plant cane the pre-oviposition period was 5·3 days; egg production was highest during the first six days of the oviposition period and declined markedly after 12 days. Mean daily egg production per female over 12 days was taken as an index of fecundity.

The effects of fertiliser application (ammonium sulphate and potassium chloride), wet and dry water regimes, variety (B41227, B42231 and B4362) and crop cycle (plant and ratoon cane), all at different stages of crop development, were observed in four series of experiments involving 1 000 female S. saccharivora. Potassium (K2O) and phosphorus (P2O5) per cent lamina dry matter varied comparatively little, but nitrogen content declined with the age of the plant, increased with application of ammonium sulphate, and was unaffected by crop cycle or variety. Egg production was highest on young cane (up to a mean of 12·0 eggs per female per day), but declined on older cane; it increased with the application of ammonium sulphate but was unaffected by potassium chloride. A direct linear correlation between egg production and the nitrogen content of the leaf (r2 = 0·69, 0·81, 0·52 and 0·69 in series I–IV, respectively) suggested a causal relationship. The pre-oviposition period lengthened and the proportion of females failing to lay any eggs increased in the absence of fertiliser and with increasing plant age. Variation in leaf nitrogen under field conditions could affect egg production.