Flatulence can cause discomfort and distress but there are few published data of normal patterns and volumes. Twenty four hour collections were made using a rectal catheter in 10 normal volunteers taking their normal diet plus 200 g baked beans. Total daily volume ranged from 476 to 1491 ml (median 705 ml). Women and men (both n=5) expelled equivalent amounts. The median daily flatus hydrogen volume was 361 ml/24 h (range 42-1060) and the carbon dioxide volume 68 ml/24 h (range 25-116), three volunteers produced methane (3, 26, and 120 ml/24 h), and the remaining unidentified gas (presumably nitrogen) or gases contributed a median 213 ml/24 h (range 61-476). Larger volumes of flatus were produced after meals than at other times. Flatus produced at a faster rate tended to contain more fermentation gases. Flatus was produced during the sleeping period, but the rate was significantly lower than the daytime rate

Cow’s milk is the most important dietary source of iodine in the UK and Ireland, and also contributes to dietary selenium intakes. The aim of this study was to investigate the effect of season, milk fat class (whole; semi-skimmed; skimmed) and pasteurisation on iodine and selenium concentrations in Northern Ireland (NI) milk, and to estimate the contribution of this milk to consumer iodine and selenium intakes. Milk samples (unpasteurised, whole, semi-skimmed and skimmed) were collected weekly from two large NI creameries between May 2013 and April 2014 and were analysed by inductively coupled plasma-mass spectrometry (ICP-MS). Using milk consumption data from the National Diet and Nutrition Survey (NDNS) Rolling Programme, the contribution of milk (at iodine and selenium concentrations measured in the present study) to UK dietary intakes was estimated. The mean ± standard deviation (SD) iodine concentration of milk was 475.9 ± 63.5 µg/kg and the mean selenium concentration of milk was 17.8 ± 2.7 µg/kg. Season had an important determining effect on the iodine, but not the selenium, content of cow’s milk, where iodine concentrations were highest in milk produced in spring compared to autumn months (534.3 ± 53.7 vs. 433.6 ± 57.8 µg/kg, respectively; p = 0.001). The measured iodine and selenium concentrations of NI milk were higher than those listed in current UK Food Composition Databases (Food Standards Agency (FSA) (2002); FSA (2015)). The dietary modelling analysis confirmed that milk makes an important contribution to iodine and selenium intakes. This contribution may be higher than previously estimated if iodine and selenium (+25.0 and +1.1 µg/day respectively) concentrations measured in the present study were replicable across the UK at the current level of milk consumption. Iodine intakes were theoretically shown to vary by season concurrent with the seasonal variation in NI milk iodine concentrations. Routine monitoring of milk iodine concentrations is required and efforts should be made to understand reasons for fluctuations in milk iodine concentrations, in order to realise the nutritional impact to consumers.

Cows' milk is a relatively poor source of vitamin D but figures listed in UK food composition tables may be outdated. Samples of milk were collected for 1-year and vitamin D3 concentrations analysed using HPLC. Milk consumption data were obtained from the National Diet and Nutrition Survey (Years 1-4). A theoretical model applied vitamin D3 fortifications of 1μg, 1.5μg and 2μg/100g to simulate improvements in vitamin D intakes. Mean±SD vitamin D3 in whole milk was 0.06±0.02μg/100g. No seasonal differences were apparent. Fortification of cows' milks with 1μg, 1.5μg and 2.0μg/100g, theoretically increased median vitamin D intakes from 2.0μg/day to 4.2μg, 5.1μg and 5.9μg/day, respectively. Higher vitamin D3 in milk from this study than that currently in food composition tables, suggests further analysis is warranted. This model suggests vitamin D fortification of cows' milk is an effective strategy to help more of the population achieve recently revised RNIs for vitamin D.

Vitamin D is obtained by cattle from the diet and from skin production via UVB exposure from sunlight. The vitamin D status of the cow impacts the vitamin D content of the milk produced, much like human breast milk, with seasonal variation in the vitamin D content of milk well documented. Factors such as changes in husbandry practices therefore have the potential to impact the vitamin D content of milk. For example, a shift to year-round housing from traditional practices of cattle being out to graze during the summer months and housed during the winter only, minimises exposure to the sun and has been shown to negatively influence the vitamin D content of the milk produced. Other practices such as changing dietary sources of vitamin D may also influence the vitamin D content of milk, and evidence exists to suggest genetic factors such as breed can cause variation in the concentrations of vitamin D in the milk produced. The present review aims to provide an overview of the current understanding of how genetic and environmental factors influence the vitamin D content of the milk produced by dairy cattle. A number of environmental and genetic factors have previously been identified as having influence on the nutritional content of the milk produced. The present review highlights a need for further research to fully elucidate how farmers could manipulate the factors identified to their advantage with respect to increasing the vitamin D content of milk and standardising it across the year.

The majority of vitamin D required by humans is derived by ultraviolet (UV) radiation of the 7-dehydrocholesterol in the skin (1) . Vitamin D can also be obtained from the diet, and these sources of vitamin D are of particular importance here in the UK and Ireland as a number of factors, including age, skin pigmentation, clothing and the use of sun protection, and geographical location, negatively influence the skin's ability to synthesise the vitamin (2) . Milk is a source of naturally occurring vitamin D (albeit providing a small contribution); the vitamin D content of whole, semi-skimmed and skimmed milk is currently listed as 0.03 μg, 0.01 μg and trace per 100 g, respectively (1) . Numerous studies have reported the effectiveness of dairy fortification as a strategy to increase dietary vitamin D intakes at the population level (3,4) . The aim of this study was to use population level dietary data to simulate how fortified cow's milk could contribute to total dietary vitamin D intake using a dietary modelling approach.Data from the National Diet and Nutrition Survey (NDNS) rolling programme (2008)(2009)(2010)(2011) were obtained from the UK Data Service (5) . A total of 12,239 recorded diary days (n3,073) were available for analysis. The vitamin D content of whole, semi-skimmed, skimmed and 1% fat milk was then manipulated to apply three incremental levels of fortification (1 μg, 1.5 μg and 2 μg per 100 ml), and the effect on total vitamin D intake was investigated in all milk consumers.A total of 82.5% diary days reported an intake of cow's milk, with intakes of consumption ranging from 2-1,764 ml with a mean intake of 202 (SD 180) ml/d. While semi-skimmed milk proved the most popular type of milk among consumers (51% of diary days), the mean volume of whole milk consumed was higher, compared to that of semi-skimmed milk (249.7(SD 207) vs.187(SD 162.1 ml/d; P < 0.001). As a result, the simulated fortification of whole milk showed the greatest increase in total vitamin D intake.Results show that fortification of UK cow's milk with vitamin D, at concentrations similar to that applied in the US/Canada (approximately 1 μg/100 ml), would significantly increase consumer's vitamin D intake. Such fortification would therefore be an effective strategy to increase vitamin D intakes, and subsequently improve the vitamin D status at the population level. While this study has focused solely on the effect of vitamin D fortification of cow's milk, more research is needed to investigate the impact of such fortification on the vitamin D content of other dairy products and their contributions to consumer's dietary vitamin D intakes.