User's comments:
"In order to increase my antioxidant intake, everyday, I drink a blend (not juice) of the following vegetables: broccoli, cauliflower, kale, parsley, tomato. Twice per week, I include cabbage.
I was concerned that perhaps one or two of these vegetables might interfere with the body's ability to absorb all of the nutrients. In other words, should I be mixing these vegetables together?
I also eat a single serving of the following fruits every day: cranberries, strawberries, blueberries, and a kiwi and have the same question about the mixing of these.
If you think I might be missing out on a great fruit or vegetable that I might add, please let me know."
Expert's comments:
"Antioxidant" is the name used to describe vitamins such as C, E and A, beta-carotene and other carotenoids, certain enzyme systems, e.g. glutathione, ubiquinones, bioflavanoids and lycopene and some minerals such as selenium.
An antioxidant is a substance which protects cells from the damaging effects of highly reactive oxygen molecules, called free radicals, which can contribute to cancers, inflammation, arterial damage and ageing. Some are made by the body, while others such as vitamin C, E, A and beta-carotene are obtained through diet or supplements.
Looking at your daily intake, you seem to be covering all the bases in terms of providing your body with the necessary ammunition to strengthen its defence mechanisms. Natural dietary sources and consumption of antioxidant-rich, whole foods is always preferred and recommended instead of taking potentially mega doses through supplementation.
The “5-A-DAY” goal for fruit and vegetable consumption is an easy way to meet at least the minimum requirements of the essential nutrients and fibre obtained from this food group. You are eating well over this recommendation.
The combination of vegetables or fruits together will not inhibit vitamin or mineral absorption. In fact, ensuring that a variety of different fruits and vegetables are consumed daily will enable you to obtain the full complement of beneficial vitamins, minerals and antioxidants provided by the different sources.
Here are just a few reminders regarding the main antioxidants obtained from dietary sources:
Vitamin C
Vitamin C is abundant in vegetables and fruits eaten raw. Frozen vegetables tend to have well preserved levels of vitamin C. Vitamin C is very easily lost in processing and cooking, because it is highly soluble (particularly in water) and is often discarded in cooking water.
It is easily destroyed by air, especially in the presence of heat and an alkaline solution. Cooking vegetables in very little water, or steaming them, help to preserve more of this water-soluble vitamin.
Food group
Good sources
Fruit
Citrus fruit, guava, pineapple, strawberries, berries, kiwi
fruit
Vegetables
Tomatoes, potatoes, cauliflower, green vegetables (e.g.
broccoli)
Vitamin E
Cooking, storing and processing reduce the vitamin E content of food. Vitamin E is insoluble in water and is thus not lost when cooking in water, but can be lost by deep-fat frying – another good reason to prepare food healthily and to avoid or limit deep-fat frying.
For your age, your recommended daily intake of these antioxidants is the following:
Vitamin C: 90 mg/day
Vitamin A: 900 ug/ day
Vitamin E: 15 mg/ day
What about antioxidant supplementation?
Supplementation may not be as advisable as previously thought. Recent research indicates that uncontrolled supplementation of antioxidants could in fact be detrimental and even increase the risk of death.
A recent meta-analysis of data from 68 well-conducted trials with 232 606 participants in Europe, the Americas, Asia and Australia, including lower- and higher-income countries, indicate that antioxidant supplements, singly or in combination with other nutrients, given at different doses and duration increase all-cause mortality.
The following were key findings:
Singly or in combination with other supplements, supplementation with beta carotene increased mortality significantly
Vitamin A supplementation in combination with other supplements, increased mortality significantly
Vitamin E given on it's own or in combination significantly increased mortality
Vitamin C supplementation was not found to increase mortality or longevity
Selenium given in combination or as a single supplement was found to have no significant effect on mortality; it tended to have a protective effect, but more research is necessary to confirm this effect
Beta carotene, vitamin A and vitamin E in single preparations or in different combinations significantly increased mortality
This data is not relevant in populations with specific needs and confirmed deficiencies of antioxidants or other nutrients.
A better and urgent understanding of the mechanisms and actions of antioxidants in relation to disease and disease progression is needed.
So before just popping a pill, please consider the following:
Make sure you are consuming an adequate diet which includes a variety of foods including sufficient fruits and vegetables. Consult an expert on the adequacy of your diet if unsure.
Avoid supplements with glamorous multi-claims which cannot be substantiated when scrutinised. Avoid single nutrient supplements.
Check the composition of the supplement you plan to take or you are taking. Choose a multi-vitamin, multi-mineral supplement that contains up to 2-3 times the recommended intake for your age.
Reassess your need to take such supplements regularly particularly for prolonged periods.
Should you experience any adverse effects possibly linked to the supplements, consult your doctor.
Helpful source of information: NICUS (Nutrition Information Centre, University of Stellenbosch) - www.sun.ac.za/nicus.
I presume that in combination with your fruit and vegetable regime, you eat an otherwise balanced diet, including fibre-rich carbohydrates, a moderate intake of protein and a low intake of healthy fats.
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