Question

5. According to your experimental results, how much vitamin C would you get from a 4 oz. (120 mL) serving of fresh orange juice?

a. Less than the RDA.

b. More than the RDA.

c. Almost exactly the RDA.

Explain your answer:

Answer 1

Ans- (b) obtion is correct.

reason-

Generally far more important than ripening and storage effects, is the effect of the variety of fruit. In some fruits, the amount of
vitamin C varies between different varieties of the same species. The tropical guava, Psidium guajava, is regarded as an excellent source of vitamin C, but there is great variation in vitamin C levels amongst the various cultivated varieties. For example, the variety 'Donaldson' has 372 mg/100 grams of flesh, but the variety 'Supreme' has only 44 mg/100 gms (some South African pink guava cultivars grown for the canning industry are said to have an astonishing 400 mg/100 gms!). Again, for mangoes, the varieties 'Pirie' and 'Haden' are only 'fair' sources, where other varieties are 'excellent' sources.The current (1989) recommended daily allowance (RDA) for an adult is 60 milligrams per day (this is based on the amount of vitamin C needed to prevent clinical scurvy and provide body stores sufficient to prevent scurvy for around 30 days, plus "a margin of safety"). Pregnant and lactating women are regarded as needing more than this. Some people claim that the optimum intake is 500 mg per day. Recent test on healthy males clearly show 200mg per day is required to maintain tissues at full saturation, but without excreting vitamin C. Women have not been tested. At April 1999, it is being 'officially' recommended, based on new information, that the RDA ought to be changed to 120 milligrams per day. The daily intake for a gatherer hunter would depend on the season, the particular ecosystem the tribe was living in, and the size of the family unit that shared whatever resource was available. The daily intake would probably have been well in excess of the RDA at times of year when fruit and greens were relatively abundant, and at other times may well have been much less. Either way, it is unlikely we took in 500 mg per day every day. The 500 mg so called 'optimum' probably reflects the need for a city living human to protect against stressful living, and the now wide exposure to damaging environmental chemicals. Such a level can only realistically be obtained by taking supplemental vitamin C.

Nutritionists generally regard any 'serving' of food that provides 10% to 25% of the daily vitamin C need in a relatively low calorie package as a 'good' source. The serving size most of us choose is pretty uniform - most of us would eat one apple, half an avocado in a salad, half a medium sized tomato as part of a salad, one banana, a slice of melon, and so on. On this basis, some fruits, such as kiwifruit, are quite outstanding, in that they provide more than the RDA in one relatively small fruit. Other fruits, such as oranges, are both very good sources and are also cheap, and pack in a lunch without crushing or leaking. So their importance is much greater than their vitamin C contentalone would suggest.Vitamin C is an important anti-oxidant, helps protect against cancers, heart disease, stress, it is part of the cellular chemistry that provides energy, it is essential for sperm production, and for making the collagen protein involved in the building and health of cartilage, joints, skin, and blood vessels. Vitamin C helps in maintaining a healthy immune system, it aids in neutralizing pollutants, is needed for antibody production, acts to increase the absorption of nutrients (including iron) in the gut, and thins the blood. Just to mention its most important functions.