Nutritional Supplements | Do They Help Prevent Disease & Slow Ageing?

Are Nutritional Supplements Necessary?

Nutritional supplements include vitamins, minerals and antioxidants.  There is much debate about the efficacy of nutritional supplements in improving health, especially if you’re already following a healthy diet. The latest research by Harvard Medical School, suggests that while there may be some benefit in taking certain supplements, there is no evidence from randomized controlled trials for the effectiveness of others. Infact, it could even be dangerous to overdose on certain nutritional supplements. Here we try to separate the truth from the hype and take a look at which supplements can help complement a healthy diet.

Meeting Your Nutritional Needs Through A Healthy Diet

The first thing to be aware of is that a diet based on the healthy food pyramid, should provide your nutritional needs, if you’re eating a wide variety of foods and including all food groups. However it is clear that many people today do not eat a well balanced diet, therefore may need to supplement with pills. In addition, some nutritional supplements can have a therapeutic effect and are used to manage specific health conditions. In either case, you should talk to your doctor and obtain advice on what nutritional supplements to take, and at what dosages. Especially considering that supplements can also have side effects and potential interactions with other medicines that you may be taking. A key point to remember is that supplements cannot replace food. Whole foods such as fruits, vegetables, nuts, seeds, legumes and wholegrains contain a variety of nutrients, fibre, vitamins, minerals and antioxidants. Eating a variety of these whole foods is the best way to obtain nutrients that your body needs.

Nutritional Supplements Facts

Recommendations for which nutritional supplements to take are constantly changing as scientific evidence from controlled trials slowly comes in. There is no absolute consensus on what the recommended daily allowance (RDA) should be, and this also varies depending on age and gender. However, the table below reflects current opinion on what upper limits are safe to take.

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Vitamin A

In nature Vitamin A comes from retinol (liver, dairy products and eggs) or beta-carotene in brightly coloured fruits and vegetables (carrots, tomatoes, spinach, sweet potato, leafy vegetables, mango, papaya and apricot). It is needed for tissue and bone growth, and immune function. Vitamin A protects eyes and skin from UV damage. 

As Vitamin A is stored in the body, consuming too much can be toxic. Get it from food instead of from nutritional supplements.


700 mcg RAE* 

*Retinol Activity Equivalents

Don’t Exceed:

3000 mcg RAE

Vitamin B

The B complex includes vitamins B1, B2, B3, B5, B6, B12, folic acid, biotin, choline, inositol and PABA. These vitamins are needed for the health of nerves, hair, skin, and eyes, as well as for combating stress.

Foods rich in vitamin B include cereals such as rice, wheat and barley, liver, dairy products, green leafy vegetables, peanuts, bananas, eggs, poultry and dried beans.

3 of the B vitamins (B6, B12 and folic acid were thought to lower high levels of homocysteine and lower risk of heart disease. However the results of clinical trials have not supported this claim. 

Having said this, it is still thought that older people and strict vegetarians who do not get sufficient B12 (which is only found in animal foods) may benefit from nutritional supplements. Additionally, the NIH recommends that pregnant women take 400 mg of folic acid daily, as it can reduce the risk of birth defects.



Don’t Exceed:

100mg for B6

Other’s are not confirmed.


Vitamin C

Vitamin C is an antioxidant and protects the body from harmful free radicals and chemicals. It is also needed for the formation of collagen for healthy gums, teeth and blood vessels. 

Foods high in Vitamin C are red bell peppers, mustard greens, watermelon, broccoli, strawberries, oranges, lemon juice, tomatoes, grapefruits, turnip, cabbage and cauliflower.

It was thought for decades that Vitamin C helps prevent the common cold. However, recent research shows that it has little to no effect.

The recommendation is to get Vitamin C from foods instead of pills.


75 mg

Don’t Exceed:

2000 mg

Vitamin D

Vitamin D is needed for healthy bone formation. It also helps to reduce risk of neuromuscular problems, certain cancers and autoimmune diseases.

Vitamin D is synthesized from sunlight when our bare skin is exposed to it and can also be obtained from diet. However, obtaining a sufficient amount of vitamin D from diet and sunlight can be difficult as there are very few foods that contain vitamin D (fish, fish liver oils, beef liver, fortified dairy products, egg yolks). It is a good idea to see your doctor to asses if you have adequate Vitamin D.

There are two types of vitamin D supplements available on the market, vitamin D2 (ergocalciferol) and vitamin D3 (calciferol). Generally many nutritionists recommend vitamin D3 as humans synthesize this form of the vitamin in the presence of sunlight.

The recommendation is that Vitamin D supplementation is a good idea for most adults.


600-800 IU

Don’t Exceed:

4000 IU


Calcium is needed to build strong bones and teeth and for nerve function. It also should be noted that your body needs Vitamin D to absorb calcium. Research suggests that people who are deficient in calcium are more likely to be overweight. When calcium levels are low in the body, parathyroid hormone is released. This causes release of calcium from your bones into your blood to restore the blood calcium level. Parathyroid hormone also stimulates fat production and inhibits fat breakdown therefore the final effect is a decrease in fat breakdown and hence increased weight. A deficiency in magnesium can also lead to calcium depletion.

Calcium is mainly found in dairy products such as eggs, milk, yoghurt and cheese. It is also found in non-dairy products such as tofu, sardines, almonds, spinach, brocolli and fortified orange juice.

Two types of calcium supplements are calcium citrate and calcium carbonate. There are also some downsides associated with calcium supplementation such as potential increase of risk for prostrate cancer. Once again, speak to your doctor before supplementing.

The recommendation is that Calcium nutritional supplements are a good idea for people who don’t get enough calcium from their diet, women who are at high risk for osteoporosis  and elderly people.


1000-2000 mg

Don’t Exceed:

2000 mg

Vitamin E

Vitamin E is an antioxidant therefore plays a role in protecting the body from the effects of toxins. It was believed for many years that Vitamin E was of benefit against heart disease and cancer. However, clinical trials do not support this. Infact, recent studies have also shown an increased risk of hemorrhagic stroke with high vitamin E intake.

Vitamin E is found in whole grains, wheatgerm, brown rice, eggs, almonds, sunflower seeds, papaya, spinach, olives, avocado, carrot, peanuts and corn oil.

Vitamin E  nutritional supplements are therefore not recommended. You should get it from your food.


15 mg

Don’t Exceed:

1000 mg


Potassium is necessary to keep muscles, heart, nervous system and digestive system healthy. Low levels of potassium can increase the risk of certain diseases. Additionally, some people may have potassium deficiency, from use of medicines such as diuretics, or if they sweat excessively. However, as we age, and kidney function slows down, the level of potassium in our blood can rise to high levels. It is also important to note that if your sodium intake is high, your potassium will be low therefore it is important to limit your salt intake to a certain extent. Alcohol and caffeine also shift potassium balance in the body as more potassium is excreted in the urine. Hence it is a better to get your doctor to do a blood test before supplementing. 

Pottasium is found in spinach, avocado, soya flour, bran wheat, sultanas, figs, nuts, sweet potatoes and bananas.

The recommendation is that you should obtain potassium from food instead of pills, unless your doctor has prescribed it.


2000-3500 mg

Don’t Exceed:

Not known.


Magnesium is a vital mineral in the body, and is used in multiple processes including transmission of nerve impulses, enzyme reactions, binding  of hormone receptors, DNA synthesis and many more functions. Most people get sufficient magnesium from their foods, however some people are at risk of magnesium deficiency especially if they have illnesses such as diarrhoea, celiac disease, or are on certain medications. Magnesium supplements may also help people who suffer from cramps and those who at risk  of osteoporosis, as Magnesium is needed for calcium absorption in to the bones. In such cases, their doctor may prescribe magnesium nutritional supplements. 

Magnesium is found in green leafy vegetables like spinach, in nuts, potatoes, beans, brown rice, wholegrain cereals, and fish.

The recommendation is that you should obtain magnesium from food instead of pills, unless your doctor has prescribed it.


300-400 mg

Don’t Exceed:

400 mg


Selenium is an mineral cofactor  that activates the antioxidant enzyme glutathione peroxidase. It was thought that selenium could reduce the risk of prostrate cancer and heart disease , but a trial conducted in 2009 proved otherwise. Infact, toxicity can occur with excessive selenium supplementation, and there is also concern that high levels of selenium may increase the risk of skin cancer and type 2 diabetes. Research is ongoing.

Selenium is found in fish, oysters, chicken, waffles, lobster, crab, flour, rice, spaghetti, macaroni, noodles, cheese, milk and brazil nuts. 

The recommendation is that you should obtain selenium from food only. 


55 mcg

Don’t Exceed:

400 mcg

Coenzyme Q

CoQ10, also known as ubiquinone is an antioxidant that is produced in the body and helps burn carbohydrates and fats, producing ATP, or energy, in simple terms. As we get older, CoQ10 production slows down, but most healthy people produce sufficient quantities of CoQ10. There is some evidence that nutritional supplements with CoQ10 may help lower blood pressure slightly, may help treat heart failure and improve symptoms such as muscle cramps, associated with taking statin drugs. However the evidence is controversial and more research is needed.

CoQ10 is found in many fruits and vegetables including spinach, broccoli, cauliflower, oranges and strawberries. In addition it is also present in meat, fish and legumes.

The recommendation is that you should obtain CoQ10 from food instead of pills, unless your doctor has prescribed it.


60-200 mg

Don’t Exceed:

Not known


L-Carnosine is a naturally occurring amino acid and has antioxidant properties. It prevents glycosylation and blocks beta amyloid buildup. As a result there have been many claims that it has anti-ageing effects. While the scientific evidence for this is scant, some researchers have found evidence that L-Carnosine improves insulin sensitivity in people who are at risk for Type 2 diabetes. Other studies also suggest that it may improve exercise performance, mood and cognition. However, much more research is required.

L-Carnosine is found in meat, poultry and fish.

The recommendation is that you should obtain Carnosine from food instead of pills, at least until more evidence is obtained from controlled trials.


Not established

Don’t Exceed:

Not known

Alpha Lipoic Acid

Alpha Lipoic Acid (ALA) is a naturally occuring fatty acid antioxidant. The body uses it to produce energy from glucose. ALA acid is made naturally in the body and healthy people produce as much ALA as their body requires. However there is evidence from reasearch studies that ALA may help reduce blood sugar levels in diabetics, and also with peripheral neuropathy which is a condition that affects the nerves and causes pain, numbing, tingling and weakness in the arms and legs. Having said that, much more research is required, and this supplement should only be taken if prescribed by your doctor.

ALA is also found in certain foods such as spinach, broccoli, potatoes, red meat, organ meats and yeast. However, ALA from foods does not appear to raise ALA levels in the body.

The recommendation is that you should not supplement with ALA unless advised by your doctor.


300-1800 mg for treating  type 2 diabetes or peripheral neuropathy.

Don’t Exceed:

Not known


 Melatonin is a natural light-sensitive hormone that is released by the pineal glands in response to the day-night cycle. The level of melatonin in the bloodstream is low during the daylight hours, and increases towards evening, reaching a peak at about midnight. As daylight begins to dim, the eyes send a signal to the brain to release natural melatonin which results in the feeling of sleepiness. Studies have shown that nutritional supplementation with Melatonin may help people who suffer from sleep disorders, sleep problems from shift work, insomnia and jet lag. It has no short-term sife effects, however it is not known haw safe it is to take Melatonin in the long term. Research is ongoing into the use of Melatonin for improving cancer care, Alzheimer’s disease and reduction of elevated night time blood pressure. At the moment there is no evidence to support the effectiveness of Melatonin for any of these conditions.

Melatonin is found in a wide variety of foods. The highest concentration is in eggs, fish, lentils, kidney beans, pistachios, almonds, coffee beans, grapes, tart cherries, tomatoes and peppers. Medical herbs such as St John’s Wort also contain high levels of Melatonin.

The recommendation is that you should obtain Melatonin from food instead of pills, as the bioavailability of oral Melatonin taken from supplements is poor compared to the level of circulating melatonin from food sources. However, it may be of use for sleep disorders, in which case you should obtain a prescription from your doctor for it.


For insomnia: 2- 3mg

For jet lag: 1 – 3mg  taken on the day of arrival and continued for up to 5 days.

Don’t Exceed:

Not known


Resveratrol is an antioxidant compund found in various plants that acts an antibiotic. There have been laboratory experiments done on mice and yeasts that have led to claims that Resveratrol may decrease the risk of heart disease, cancer and dementia and extend life span. However, the reality is that there have been only a few human studies, and little is understood about side effects. Therefore, there is a long way to go with regards to research into this nutritional supplement. Additionally grape seed extract is also sold as a supplement which contains resveratrol.

Resveratrol is found in red and purple grapes, mulberries, blueberries, cranberries, peanuts, and pistachios

The recommendation is that you should obtain Resveratrol from food instead of pills.


20-50 mg

Don’t Exceed:

Not known.

Side effects like over thinning of the blood, diarrhoea, headaches and anxiety have been observed in doses greater than 500 mg

Glucosamine & Chondroitin

Glucosamin and Chondroitin are natural components of joint cartilage. Supplements are commercially manufactured from shellfish, shark cartilage and also plant sources. Pills containing a combination of glucosamine and chondroitin are used to treat osteoarthritis. However, there is huge controversy in the scientific community as to the effectiveness of this treatment. The American College of Rheumatology as well as American Academy of Orthopaedic Surgeons recommend against the use of these supplements. Although initial clinical trials appeared provide evidence that these supplements relieved the symptoms of osteoarthritis, more recent research carried out in 2010 proved otherwise. As there are minimal side effects, some doctors may prescribe these supplements to their patients to try out for a few months for pain relief.

Glucosamin and Chondroitin are not found naturally in many foods, although cartilage in the bones of meat and poultry are a source. In addition, these compunds are found in shellfish. Shellfish and cartilage can be added into a broth, soups and stews.

The recommendation is that you should not supplement with glucosamin or chondroitin, unless your doctor suggests that you try it out for arthritis pain relief.


Up to 1500 mg for glucosamine and 1200 mg per day for chondroitin for  up to 90 days

Don’t Exceed:

Not known

Fish Oil

Fish Oil supplements contain essential fatty acids required by the body for certain processes. Omega 3 and Omega 6 are fatty acids need to be obtained from the diet. However Omega 6 fatty acids are present in our diets in large quantities, and we actually need to increase the level of Omega 3’s to normalize the ratio between the two.The majority of supplements in the market contain two out of eight Omega-3 elements, eicosapentonoeic acid (EPA) and docosahexenoic acid (DHA). Although nutritional supplementation with fish oil has been promoted as being beneficial for the heart, the latest research suggests otherwise. The American Heart Association has updated its recommendation for fish oil supplements to “fish oil supplements may slightly lower the risk of dying of heart failure or after a recent heart attack. But they do not prevent heart disease.” There may be modest benefits for people who have heart disease, however some fish oil supplements carry the risk of contamination of PCBs, and also some brands do not provide the amounts of DHA and EPA advertised on the label.

Omega-3 oils are naturally found in fish, flaxseed, canola oil, nuts and avocados as well as some fortified eggs and dairy products.

The recommendation is that you should obtain Omega 3s  from food such as oily fish instead of pills, as this is a less risky option. If you are going to take fish oil supplements, do so with the guidance of your doctor as it can increase bleeding risk in people taking anti-clotting medications.


1000 – 1600mg of  DHA/EPA for heart disease

Don’t Exceed:


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