Concept: Dietary mineral
Nutrition usually makes a small but potentially valuable contribution to successful performance in elite athletes, and dietary supplements can make a minor contribution to this nutrition programme. Nonetheless, supplement use is widespread at all levels of sport. Products described as supplements target different issues, including (1) the management of micronutrient deficiencies, (2) supply of convenient forms of energy and macronutrients, and (3) provision of direct benefits to performance or (4) indirect benefits such as supporting intense training regimens. The appropriate use of some supplements can benefit the athlete, but others may harm the athlete’s health, performance, and/or livelihood and reputation (if an antidoping rule violation results). A complete nutritional assessment should be undertaken before decisions regarding supplement use are made. Supplements claiming to directly or indirectly enhance performance are typically the largest group of products marketed to athletes, but only a few (including caffeine, creatine, specific buffering agents and nitrate) have good evidence of benefits. However, responses are affected by the scenario of use and may vary widely between individuals because of factors that include genetics, the microbiome and habitual diet. Supplements intended to enhance performance should be thoroughly trialled in training or simulated competition before being used in competition. Inadvertent ingestion of substances prohibited under the antidoping codes that govern elite sport is a known risk of taking some supplements. Protection of the athlete’s health and awareness of the potential for harm must be paramount; expert professional opinion and assistance is strongly advised before an athlete embarks on supplement use.
BACKGROUND: Vitamin K2 contributes to bone and cardiovascular health. Therefore, two vitamin K2 homologues, menaquinone-4 (MK-4) and menaquinone-7 (MK-7), have been used as nutrients by the food industry and as nutritional supplements to support bone and cardiovascular health. However, little is known about the bioavailability of nutritional MK-4. To investigate MK-4 and MK-7 bioavailability, nutritional doses were administered to healthy Japanese women. FINDINGS: Single dose administration of MK-4 (420 mug; 945 nmol) or MK-7 (420 mug; 647 nmol) was given in the morning together with standardized breakfast. MK-7 was well absorbed and reached maximal serum level at 6 h after intake and was detected up to 48 h after intake. MK-4 was not detectable in the serum of all subjects at any time point. Consecutive administration of MK-4 (60 mug; 135 nmol) or MK-7 (60 mug; 92 nmol) for 7 days demonstrated that MK-4 supplementation did not increase serum MK-4 levels. However, consecutive administration of MK-7 increased serum MK-7 levels significantly in all subjects. CONCLUSIONS: We conclude that MK-4 present in food does not contribute to the vitamin K status as measured by serum vitamin K levels. MK-7, however significantly increases serum MK-7 levels and therefore may be of particular importance for extrahepatic tissues.
Selenium (Se) is an essential human micronutrient with critical roles in immune functioning and antioxidant defence. Estimates of dietary Se intakes and status are scarce for Africa although crop surveys indicate deficiency is probably widespread in Malawi. Here we show that Se deficiency is likely endemic in Malawi based on the Se status of adults consuming food from contrasting soil types. These data are consistent with food balance sheets and composition tables revealing that >80% of the Malawi population is at risk of dietary Se inadequacy. Risk of dietary Se inadequacy is >60% in seven other countries in Southern Africa, and 22% across Africa as a whole. Given that most Malawi soils cannot supply sufficient Se to crops for adequate human nutrition, the cost and benefits of interventions to alleviate Se deficiency should be determined; for example, Se-enriched nitrogen fertilisers could be adopted as in Finland.
Vitamin D insufficiency in children may have long-term skeletal consequences as vitamin D affects calcium absorption, bone mineralization and bone mass attainment.
Weight-loss diets restrict intakes of energy and macronutrients but overlook micronutrient profiles. Commercial diet plans may provide insufficient micronutrients. We analyzed nutrient profiles of three plans and compared their micronutrient sufficiency to Dietary Reference Intakes (DRIs) for male U.S. adults. Hypocaloric vegan (Eat to Live-Vegan, Aggressive Weight Loss; ETL-VAWL), high-animal-protein low-carbohydrate (Fast Metabolism Diet; FMD) and weight maintenance (Eat, Drink and Be Healthy; EDH) diets were evaluated. Seven single-day menus were sampled per diet (n = 21 menus, 7 menus/diet) and analyzed for 20 micronutrients with the online nutrient tracker CRON-O-Meter. Without adjustment for energy intake, the ETL-VAWL diet failed to provide 90% of recommended amounts for B12, B₃, D, E, calcium, selenium and zinc. The FMD diet was low (<90% DRI) in B₁, D, E, calcium, magnesium and potassium. The EDH diet met >90% DRIs for all but vitamin D, calcium and potassium. Several micronutrients remained inadequate after adjustment to 2000 kcal/day: vitamin B12 in ETL-VAWL, calcium in FMD and EDH and vitamin D in all diets. Consistent with previous work, micronutrient deficits are prevalent in weight-loss diet plans. Special attention to micronutrient rich foods is required to reduce risk of micronutrient deficiency in design of commercial diets.
Dietary supplements, such as herbal or complementary nutritional products and micronutrients (vitamins and minerals), are commonly used in the United States, yet national data on adverse effects are limited.
Iron, potassium, zinc, and other minerals might impact the development of premenstrual syndrome (PMS) through multiple mechanisms, but few studies have evaluated these relations. We conducted a case-control study nested within the prospective Nurses' Health Study II (1991-2001). Participants were free from PMS at baseline. After 10 years, 1,057 women were confirmed as PMS cases and 1,968 as controls. Mineral intake was assessed using food frequency questionnaires completed in 1991, 1995, and 1999. After adjustment for calcium intake and other factors, women in the highest quintile of nonheme iron intake had a relative risk of PMS of 0.64 (95% confidence interval (CI): 0.44, 0.92; P for trend = 0.04) compared with women in the lowest quintile. Women in the highest quintile of potassium intake had a relative risk of 1.46 (95% CI: 0.99, 2.15; P for trend = 0.04) compared with women in the lowest quintile. High intake of zinc from supplements was marginally associated with PMS (for intake of ≥25 mg/day vs. none, relative risk = 0.69, 95% CI: 0.46, 1.02; P for trend = 0.05). Intakes of sodium, magnesium, and manganese were unrelated to PMS risk. These findings suggest that dietary minerals may be useful in preventing PMS. Additional studies are needed to confirm these relations.
Although breakfast consumption is widely considered to be an important component of a healthy lifestyle, few UK studies have examined differences in nutrient intakes between breakfast consumers and breakfast skippers among children and adolescents. We investigated associations between breakfast skipping in 4-18-year-olds and their nutrient intakes using data from the UK’s National Diet and Nutrition Survey Rolling Programme. Dietary data were derived from 4-d estimated food diaries of 802 children aged 4-10 years and 884 children aged 11-18 years (1686 in total). Daily nutrient intakes of children with different breakfast habits were compared by one-way ANCOVA adjusting for relevant covariates (sex, age, ethnicity, equivalised household income and BMI). Within-person analysis was carried out on children with an irregular breakfast habit (n 879) comparing nutrient intakes on breakfast days with those on non-breakfast days using repeated measures ANCOVA. We observed that the overall nutritional profile of the children in terms of fibre and micronutrient intake was superior in frequent breakfast consumers (micronutrients: folate, Ca, Fe and I (P<0·01)) and, for the 4-10 years age group, on breakfast days (micronutrients: folate, vitamin C, Ca and I (P<0·01)). Also, significantly higher proportions of breakfast-consuming children met their reference nutrient intakes of folate, vitamin C, Ca, Fe and I compared with breakfast skippers (χ 2 analysis, P<0·001). Our study adds to the body of data linking breakfast consumption with higher quality dietary intake in school-age children, supporting the promotion of breakfast as an important element of a healthy dietary pattern in children.
Certain population sub-groups in the United States are vulnerable to micronutrient malnutrition. Nationally representative data from the National Health and Nutrition Examination Survey (NHANES) describing the biochemical status of vitamins A, B6, B12, C, D, E, folate, and anemia, were aggregated to determine the overall risk of multiple concurrent deficiencies in U.S. children and adults (n = 15,030) aged >9 years. The prevalence of deficiency risk according to socio-demographic, life-stage, dietary supplement use, and dietary adequacy categories was investigated. Thirty-one percent of the U.S. population was at risk of at least one vitamin deficiency or anemia, with 23%, 6.3%, and 1.7% of the U.S. population at risk of deficiency in 1, 2, or 3-5 vitamins or anemia, respectively. A significantly higher deficiency risk was seen in women (37%), non-Hispanic blacks (55%), individuals from low income households (40%), or without a high school diploma (42%), and underweight (42%) or obese individuals (39%). A deficiency risk was most common in women 19-50 years (41%), and pregnant or breastfeeding women (47%). Dietary supplement non-users had the highest risk of any deficiency (40%), compared to users of full-spectrum multivitamin-multimineral supplements (14%) and other dietary supplement users (28%). Individuals consuming an adequate diet based on the Estimated Average Requirement had a lower risk of any deficiency (16%) than those with an inadequate diet (57%). Nearly one-third of the U.S. population is at risk of deficiency in at least one vitamin, or has anemia.
Ensuring that a woman is well-nourished, both before and during pregnancy, is crucial for the health of the woman and that of the unborn child.(1) Maternal deficiency in key nutrients has been linked to pre-eclampsia, restricted fetal growth, neural tube defects, skeletal deformity and low birth weight.(1,2) Many nutritional supplements containing vitamins, minerals and other micronutrients are heavily marketed to women for all stages of pregnancy. However, much of the evidence for vitamin supplementation in pregnancy comes from studies carried out in low-income countries,(3) where women are more likely to be undernourished or malnourished than within the UK population. The challenges lie in knowing which supplements are beneficial and in improving uptake among those at most need. Here we summarise current UK guidance for vitamin supplementation in pregnancy and review the evidence behind it.