Vitamin Intake of Female College Students 

Prof. Kazuto YASUDA and Mami Hiraoka, Laboratory of Clinical Chemistry, the Graduate School of Nutrition Sciences 
[Abstract]
          Recently, physical activity in the daily lives of Japanese people has changed considerably and the number of low level of physically active people is on the rise. In a survey of female college students, the average energy intake showed a value similar to the recommended energy allowance for people whose physical activity is classified as level I (low). Although most of the subjects ingested sufficient vitamin B1 in proportion to their energy intake due to limited food intake, approximately 20% did not meet the recommended allowance in their vitamin B1 intake. In the case of vitamin A, for which the allowance is determined independently of energy intake, approximately 50% did not meet the allowance. However, few of the subjects showed decreased levels of these vitamins in the blood. It was also suggested that increased folate intake was necessary. 
       According to the National Survey on Nutrition conducted by the Ministry of Health and Welfare, Japanese people have consistently met the recommended allowance in their intake of vitamin A, B1, B2 and C since 1975. However, the results shown were for an average Japanese; there must be individuals who fail to meet the recommended allowance. This raises this question: what percent of Japanese people actually fail to meet the allowance? Most people do not eat ideal meals meeting the allowances of various vitamins, taking into account the loss of vitamins in the cooking process. What, then, is the influence of daily variation in vitamin intake? And what are the conditions concerning the intake of other vitamins, those not mentioned above? With respect to these points, we investigated the vitamin intake of young females who are likely to bear and raise children in the near future.
       The subjects were 193 female college students in the Faculty of Nutrition Sciences aged 21 to 22, with no abnormal results in routine biochemical blood tests and who do not take vitamin pills. Based on a survey of their meals conducted for three consecutive days, the average intakes of vitamin A, B1, B2, B6, niacin, vitamin B12, folate, and vitamin C and E were calculated, and the proportion of subjects who met the recommended allowance was determined for each of the vitamins. For vitamins for which the allowances are not set in the Fifth-Revised Recommended Dietary Allowances in Japan, the U. S. 10th Revision of the Recommended Dietary Allowances (USRDA) were applied. Blood vitamin levels were measured on the day following the 3-day survey to examine the relation to vitamin intake. Physically, the subjects were 158.5}5.1 cm in height, 52.4}6.1 kg in weight, and 20.8}2.1 in BMI, which was similar to the average values in 1996. In order to collect data on vitamin intake concerning individual and daily variation, the subjects were given no specific menu but were directed to maintain their usual eating habits during the survey. The subjects were students in a training course in nutriology and were directed to measure and record their meals as precisely as possible, with the understanding that their records would be graded as an assignment in the course. The survey period was determined through a preliminary survey, which confirmed that a minimum of three days was necessary before the coefficients of variation in vitamin intake dropped to an appropriate level and that the values rose again after a prolonged period.
       In the healthy female college students surveyed, vitamin B1 intake was 0.91}0.26 mg/day (the average of the 3 days}S.D.), the coefficient of variability (CV), an indicator of differences between individuals, was 28.6% (n=192), and the number of subjects who met the recommended allowance was 151 (78.6%)(Fig. 1). Assuming that 30% of vitamin B1 is lost in the cooking process, as is stated in the Standards for Enforcement of the School Lunch Law (Notification No.16 of the Ministry of Education, Science, Sports and Culture, 1986), the net vitamin B1 intake was 0.64}0.18 mg/day, in which case the number of subjects who met the recommended allowance decreases to 34.4%. However, since the energy intake of the subjects was 1,568}312 kcal, 92.3% of the subjects met the energy-based vitamin B1 allowance of 0.40 mg/1,000 kcal, on which the recommended daily allowance of the vitamin was based. This means that most of the subjects presumably had a sufficient vitamin B1 intake in proportion to their energy intake. The total vitamin B1 level in the blood of the subjects was 55.1}12.2 ng/mL, with only 2 subjects (1.0%) showing levels below the lower limit of the standard interval of 35|76 (54.6}10.1) ng/mL. It can be inferred from these results that while 21.4% of the subjects failed to meet the recommended vitamin B1 allowance specific to their sex, age, and physical activity, only a few subjects showed low vitamin B1 levels in the blood, i.e. marginal vitamin B1 deficiency, due to the fact that 20% of the allowance is actually an extra amount in consideration of individual variations in demand and that the subjects' demand for the vitamin was small        because of their relatively low energy intake and physical inactiveness.
The vitamin B2 intake of the subjects determined in a similar manner was 1.20}0.31 mg/day (CV=25.8%, n=189) and 72.0% of the subjects met the recommended allowance. If one assumes that 25% of vitamin B2 is lost in the cooking process, net vitamin B2 intake decreases to 0.90}0.23 mg/day, in which case the number of subjects who met the allowance decreased to 30.2% However, 90.8% of the subjects met the energy-based vitamin B2 allowance of 0.55 mg/1,000 kcal. The total vitamin B2 level in the blood of the subjects was 85.9}17.1 ng/mL, with only 5 subjects (2.7%) showing levels below the lower limit of the standard interval of 58|110 (84.7}11.6) ng/mL. It can be inferred from these results that while 28.0% of the subjects failed to meet the vitamin B2 allowance, only a few showed marginal vitamin B2 deficiency, due to their low energy intake and physical inactiveness, as was inferred in        the case of vitamin B1.
As for niacin intake, the niacin equivalent intake including the portion converted from tryptophan was 24.0}5.9 mg/day (CV=24.6, n=189), in which 12.6}3.6 mg/day was directly ingested in the form of niacin, while 11.4}2.8 mg/day was ingested in the form of tryptophan, resulting in a ratio of 52.2 : 47.8%. The energy-based niacin equivalent intake of the subjects was 15.3 mg/1,000 kcal/day, without a single subject showing a level below the recommended allowance of 6.6 mg/1,000 kcal. The total niacin level in the blood measured by HPLC was 487.0}119.5 ƒΚg/dL (n=189), without a single subject showing a level below the standard interval of 285|710 (487.2}97.5) ƒΚg/dL (n=189), which means there was no subject with subclinical niacin deficiency. In addition, a correlation was found between the niacin equivalent and the energy intake (r=0.670, p < 0.0001).
       The vitamin B6 intake of the subjects was 1.35}0.53 mg/day (CV=39.3%, n=185). Since the recommended vitamin B6 allowance is not set in the Fifth-Revised Recommended Dietary Allowances in Japan, fundamental values set in the USRDA were partially applied. The protein-based vitamin B6 intake of the subjects was 0.023}0.010 mg/g protein. Setting a limit of 0.016 mg/g protein, 161 subjects (87.0%) met the recommended allowance. For the group of subjects as a whole, a correlation was found between the protein intake and vitamin B6 intake (r=0.393, p < 0.0001), as well as between the niacin equivalent intake and vitamin B6 intake (r=0.439, p < 0.0001). The total vitamin B6 level in the blood serum measured by HPLC was 11.4}7.7 ng/mL (n=185), with 6 subjects (3.2%) showing levels below the standard interval of 4.0|17.0 (9.1}2.7) ng/mL.
       Folate is not covered by the Fourth-Revised Standard Tables of Food Composition in Japan, and although it is covered by the Fifth-Revised Tables, only a new food section has been published of the fifth revision. Therefore, Bowes & Church's Food Values of Portions Commonly Used 16th Ed., developed in the U. S., was used for calculation. The folate intake of the subjects was 187.3}73.3 ƒΚg/day (CV=39.1%, n=157), with 70 subjects (44.6%) meeting the U. S. recommended allowance (180 ?g/day) (Fig. 2). The folate level in the blood serum was 8.05}2.49 ng/mL, with 10 subjects (6.4%) showing levels below the lower limit of the standard interval of 4.8|12.0 (8.3}1.8) ng/mL.
       The vitamin B12 intake of the subjects was 4.88}3.55 ƒΚg/day (CV=72.7%, n=162), with 137 subjects (84.6%) meeting the U. S. recommended allowance (2.0 ƒΚg/day). The vitamin B12 level in the blood serum was 615.1}215.1 pg/mL, with one subject (0.62%) showing a level below the lower limit of the standard interval of 260|1,050 (589}170) pg/mL. The vitamin C intake of the subjects was 119.8}79.5 mg/day (CV=66.4, n=299), with 265 subjects (88.6%) meeting the allowance set in the Fifth-Revised RDA. The total vitamin C level in the blood serum was 1.25}0.26 mg/dL, with 6 subjects (2.0%) showing levels below the lower limit of the standard interval. 
       As for the intake of fat soluble vitamins, the vitamin A intake of the subjects was 1,917.2}860.0 IU/day (CV=44.9%, n=284), with 139 subjects (48.9%) meeting the recommended allowance. The retinol level in the blood serum was 42.0}12.4 ƒΚg/dL (n=284), with 5 subjects (1.8%) showing levels below the lower limit of the standard interval of 20|72 (41.8}11.1) ƒΚg/dL. The vitamin E intake was 7.27}2.22 mg/day (CV=30.5%, n=299), with 158 subjects (52.8%) meeting the safe and adequate daily dietary intake set in the Fifth-Revised RDA. ƒΏ-tocopherol level in the blood serum was 1.27}0.43 mg/dL (n=299), with 9 subjects (3.0%) showing levels below the lower limit of the standard interval of 0.58|2.25 (1.24}0.35) mg/dL.
       It can be inferred from these results that approximately 10%|30% of current female college students do not meet the recommended allowances of vitamins set in the Fifth-Revised RDA with the exception of niacin, and as for vitamin A and folate, more than 50% failed to meet the allowances. However, only 0.6|3.2% of the subjects were shown to have marginal vitamin deficiency, which was represented by blood vitamin levels below the lower limit of the standard intervals (normal values), with the exception of folate. Therefore, it was suggested that increased intake of folate was necessary. 

 
 
 
The Role of Vitamins in Disease Prevention 
from Vitamin Nutrition Research newsletter Vol.5, No.3 

Coronary Heart Disease
[Vitamin B group]
Folic acid can help to prevent heart disease by keeping blood levels of homocysteine under control. Vitamin B6 and B12 are also important for homocysteine metabolism. Older people should strive to get the recommended amounts of these vitamins.
[Antioxidant vitamins]
Antioxidant nutrients such as vitamins C and E may also help to prevent heart disease. The evidence for a protective effect is particularly strong for vitamin E. Several epidemiological studies - including one that focused specifically on senior citizens - have indicated that people who take vitamin E supplements have lower rates of death from coronary heart disease than those who do not take supplements. Vitamin E is even helpful in slowing the progression of coronary disease in people who already have heart problems.(Fig.) 

Degenerative disease of the eye 
Two serious degenerative diseases of the eye - cataracts and macular degeneration - are common among older adults. Good nutrition, including ample intakes of vitamins and antioxidants, may help to prevent or delay the onset of these disorders.
Cataract is a disorder in which the lens of the eye becomes increasingly opaque, leading to impaired vision. Epidemiological studies have shown that the risk of developing cataracts may be lower among multivitamin supplement users, vitamin C or vitamin E supplement users, and people with high dietary intakes of vitamin C than among the general population. These epidemiological findings make biological sense, since oxidative processes are involved in the causation of cataracts, and antioxidants such as vitamins C and E inhibit oxidation. Macular degeneration is a progressive disorder affecting the retina of the eye. Unlike cataract, macular degeneration cannot be treated effectively, so the need for preventive measures is especially urgent. As with cataracts, oxidative processes are involved in the causation of macular degeneration, so antioxidants may be important in preventing this condition. 
A large study conducted in five areas of the U.S. has shown that people with high dietary intakes or blood levels of antioxidants - especially carotenoids - are less likely to develop macular degeneration than those with lower intakes of these nutrients. This relationship is strongest for lutein and zeaxanthin - two carotenoids found in leafy green vegetables. These carotenoids are also present in the retina of the eye, where they may act as protective antioxidants. Beta-carotene also appears to be protective against macular degeneration. 
Fatty acid metabolism in the atopic mother
from PUFA Newsletter Vol.3, No.1 

There is evidence that breast-feeding helps protect children against developing atopic conditions such as asthma, and eczema, which are some-times hereditary in nature. However, the extent of that protection has remained a matter for debate. Now two new studies, both by the same group of investigators, may help to resolve this controversy.
In the first of these studies, G Yu, K Duchen and B Bjorksten from Linkoping University, Sweden, found differences between atopic and non-atopic women in the composition of fatty acids in the colostrum and mature milk during the first six months they were breast-feeding their babies. In the second study, in a larger group of mothers, they were able to relate such differences to the development of atopy in the babies during their first year.

Differences between atopic and non-atopic women
in the composition of fatty acids
Fist, the investigators examined 34 breast-feeding women: 17 with and 17 without atopy. Milk samples were taken 2-4 days after their babies' delivery and again after 1 and 3 months of lactation. The levels of linoleic acid [LA], alpha-linolenic acid [LNA] and their metabolites were similar in colostrum in both groups of women. Total levels of the omega-3 LC-PUFA dropped more rapidly in the atopic mothers during the first month of lactation but were restored thereafter. (Fig.1) The milk from the latter also showed a lower level of the omega-6 LC-PUFA dihomo-gamma-linolenic acid [DGLA] at one month, as well as of total omega-3 LC-PUFA, and of the individual omega-3 LC-PUFA EPA, DHA and docosapentaenoic acid [DPA]. (Fig.2) 
Differences to the development of atopy 
in the babies during their first year
This study followed 58 new mothers, of whom half were atopic and half non-atopic, until their babies were one year old. Twenty-four of the babies developed atopy. Non-atopic mothers of atopic babies were found to have higher levels of the omega-6 fatty acids gamma-linolenic acid [GLA] and DGLA when compared with the other mothers. GLA tended to increase during lactation in mothers of non-atopic babies but remained constant in those of atopic babies. There was also a trend for a more marked decrease in total omega-3 LC-PUFA acid levels [p<0.07] with time in the milk consumed by the babies who developed atopy. An increase in LNA levels in mature milk compared with colostrum was seen only in non-atopic mothers with non-atopic babies; in all other mothers, LNA levels declined, especially in atopic women with atopic babies. In addition, the levels of omega-3 LC-PUFA were lower and the ratios of omega-6/omega-3 LC-PUFA higher in the mature milk of mothers whose babies developed atopy.
AA and EPA are precursors of, respectively, more and less inflammatory eicosanoids mediators and compete with each other. The authors suggest that the lower ratios of AA/EPA in non-atopic women could mean that their breast milk would contain greater anti-inflammatory products than that of the atopic women. A similar argument might hold for the low AA/DGLA ratio, they speculate, although the metabolites of DGLA are as yet unknown. The LC-PUFA content of breast milk also affects that of the baby's serum and cell membranes, another mechanism by which it could influence the development of atopy in early childhood.
Some work has suggested that supplementation with LC-PUFA might be of benefit in atopic disease. It has been unclear, however, why babies fed breast-milk which has a higher LC-PUFA content than infant formula, are not consistently protected. The present findings provide a possible explanation. 

 
 
Topical melatonin in combination with vitamins E and C protects skin from ultraviolet-induced erythema: a hmuman study in vivo 
from British Journal of Dermatology 1998, 139 

In this randomized double-blind human study the short-term photoprotective effects of different antioxidants and their combinations were evaluated in vivo.
Subject: 
12 healthy caucasian volunteers (six men and six women: age 40}7 years (mean}SD), range 29-49) participated after providing informed consent. They were of Fitzpatrick skin type ‡Uor‡V and free from active skin diseases.
Methods:
Vitamin C (ascorbic acid), Vitamin E (ƒΏ-tocopherol) and melatonin (N-acetyl-5-methoxytryptamine) were topically applied alone or in combination (Table.1) 30 minutes before ultraviolet-irradiation of the skin. The erythemal reaction was evaluated visually and non-invasively using different bioengineering methods (6, 24, 48 hours later).
Results:
The results clearly demonstrated the efficacy of the tested antioxidants under the experimental conditions particularly of combinations thereof. Topical application of the pineal hormone melatonin resulted in a dose-dependent inhibition of the erythema formation confirming the results obtained by Bangha et al. The application of vitamin C or E alone, however, showed no or only modest effect. A much more pronounced effect was obtained by combining these two vitamins. The most dramatic improvement resulted from the coformulation of melatonin together with vitamin E and vitamin C as judged by a significantly reduced erythemal reaction.
Discussion:
UV exposure leads to depletion of the enzymic and non-enzymic skin antioxidants. Consequently, the skin antioxidant capacity is decreased and the skin becomes more susceptible to the deleterious effects of ROS. Topical application of antioxidants, such as vitamin E, provides an efficient means of replenishing the tissue in these protective compounds. The supplementation may result in a sustained antioxidant capacity of the skin particularly of the stratum corneum, which is the most susceptible skin layer for UV-induced depletion of the lipophilic antioxidant vitamin E. The cutaneous antioxidant system is complex and incompletely understood. The system is interlinked in skin, for example, ascorbate can regenerate ƒΏ-tocopherol from theƒΏ-tocopheroxyl radical. Thus, the enhanced photoprotective effect obtained after applying vitmain E combined with vitamin C, as demonstrated in this study, might be attributed to the regeneration of vitamin E by vitamin C. This hypothesis is underlined by studies using disperse systems showing a synergistic antioxidant action of these vitamins in vitro.
Vitamin C and a combination of both vitamins resulted in no significant sunscreening effect. Hence as already stated the remarkable photoprotection of the formulation containing both vitamins is mainly a consequence of the potent antioxidant properties of such a combination. On the other hand, the use of a non-solar-simulated UV source during this study emitting significant amounts of UVC influencing the development of the skin erythemal reaction may have led to an overstimation of the photoprotection by the tested compounds. Therefore, the strong UVC absorption of vitamin C as well as of malatonin should be considered when interpreting the results. Given that the skin layer most susceptible to UV-induced depletion of antioxidants is the stratum corneum and that this is also the site where UVC will act preferentially, replenishing this skin layer with exogenous antioxidants might lead to higher degree of photoprotection using a non-solar-simulated compared with a solar-simulated UV source. Therefore, further studies are necessary to confirm the obtained results using a solar-simulated source of UV radiation.
One of possible mechanism in preventing photodamage by melatonin might be through the interference of melatonin with arachidonic acid matabolism, leading to lower concentrations of prostaglandins and leukotrienes; a possible role of these metabolites in UV-induced skin erythema formation has long been recognized. Thus, diminishing their local concentration by melatonin may result in a suppressed erythema formation. Finally, an additional possible explanation for the observed enhancement of the photoprotective effect could reside in a reciprocal influence on the bioavailability in the upper skin layers of the different substances of the tested antioxidant formulations. This hypothesis is currently under investigation in our laboratories. 
Although the exact mechanisms remain to be clarified and the results obtained need to be confirmed using a solar-simulated UV source, efficient photoprotection could be obtained by appropriate mixtures of compounds having sunscreening and antioxidant properties. Combinations of melatonin with vitamins E and C seem to be such mixtures and might be used as additional ingredients in formulations intended for outdoor use and /or in sunscreens. 


 
 
 
Vitamin Nutrition for Physically Active People No.3
From VNIS BACK-GROUNDER Vol.6, No.1 

Complementary Roles of Nutrition and Physical Activity

Reducing Cardiovascular Disease Risk 
Regular exercise even at relatively moderate levels will decrease the risk of coronary heart disease, hypertension and stroke and is a recommended part of a healthy lifestyle. The cardioprotective effects of exercise could be the result of better weight control; improved glucose tolerance and insulin metabolism; reduced blood pressure; better clearance of circulating triglycerides; improved lipid and lipoprotein metabolism; improvements in coagulation and hemostatic factors; and better cardiac performance due to an enhanced ability to increase stroke volume. Ensuring adequate dietary intake of vitamins that have been shown to reduce the risk of CVD can augment and complement these beneficial effects of exercise. Just as oxidative stress can play a role in muscle injury, oxidative stress also is a critical part of the etiology of atherosclerosis. Oxidation of low density lipoprotein (LDL) is thought to be a critical step in the development of atherosclerosis, the basis for CVD. Vitamin E is effective in preventing this oxidation.
In the last few years a great deal of epidemiological evidence has suggested that intakes of vitamin E over 100 IU per day reduce the risk of coronary heart disease. This effect is seen primarily from supplement use, although in one recent study the association between vitamin E and reduced risk of death from coronary heart disease was most striking in the subgroup of women who did not take supplements, but who had high dietary intakes of vitamin E. A recent clinical trial showed that supplementation with 800 IU vitamin E for approximately 18 months reduced the risk of non-fatal myocardial infarction by 77% in patients with atherosclerosis of the coronary arteries. There are also some reports suggesting that higher intakes of vitamin C are associated with a lower risk of CVD.
Relatively new research has related intakes of folate, vitamin B6 and vitamin B12 to risk of CVD. Scientists have found that the risk of CVD is directly related to the level of homocysteine, an amino acid, in the plasma and that higher levels of these three vitamins will lower the level of homocysteine. Elevated homocysteine is a risk factor completely independent of cholesterol levels and most other accepted risk factors. Most Americans are not consuming these vitamins at levels considered desirable to limit homocysteine, which potentially may offset the benefits of other lifestyle changes they are making.

Effects on Immune Function
Frequent reports of increased susceptibility to infectious diseases among highly trained competitive athletes suggest that high intensity exercise may suppress the immune system. The levels of cortisol and catecholamines are increased during exercise. These hormones are immune-suppressive and could partially account for the decreased immunity. Specific aspects of the immune system are affected by a single session of intense exercise: for example, natural killer cell activity is reduced, and the number of specialized immune cells called CD4+ cells decreases. On the other hand, studies in mice suggest that moderate exercise may enhance the immune system, and the effect of moderate exercise on human immune function has yet to be elucidated.

Maintaining Bone Health
One of the benefits of weight-bearing exercise is a reduced risk of osteoporosis, a chronic loss of bone which can lead to life-threatening bone fractures. Nutrition also is an important factor in slowing the progression of this disease. It is generally agreed that preventive measures should start as early as possible since after menopause bone loss is more difficult to reverse. In addition to calcium, the nutrients that play an essential role in the growth and maintenance of bones are vitamins D, C, and K. Therefore, a diet that provides recommended levels of these vitamins and minerals can complement the benefits of exercise in promoting bone health.