Start the day right

When do you take your supplements? With breakfast or your evening meal? Do you wash them down with water, juice or coffee? Does it matter? Dr Sarah Brewer explains how to take supplements for optimum health.

Although it may sound obvious, to get the most benefit from your supplements, they must first be absorbed from your intestines and presented to your cells in a form they can use or store. This is known as a substance’s ‘bioavailability’. Some substances are poorly absorbed, using passive processes such as diffusion, while others are rapidly absorbed using active transport that quickly grab the nutrient from your intestines when intakes are low - selenium take-up can be as high as 98%. The amount of each absorbed nutrient that remains bioavailable varies from person to person and also changes over time - especially for nutrients such as iron and zinc, whose uptake is regulated so you do not absorb too much. Absorption often depends on the level of acidity in your stomach. As the quality of the stomach lining reduces with age (a process known as atrophic gastritis), lack of stomach acid is relatively common in older people and can lead to nutritional deficiencies. Studies show, for example, that up to 60% of people aged over 75 are deficient in vitamin B12 and 30% are deficient in folate - mostly due to atrophic gastritis which reduces B vitamin absorption.

Health conditions that reduce or speed up the flow of intestinal contents through your gut also affect absorption, as can the types of food you eat. Bran and phytate (a substance found mainly in unleavened wheat bread and beans) can bind minerals so they remain unabsorbed, reducing uptake of iron, zinc, calcium and manganese. One study found that a three-fold difference in phytate content of food could reduce calcium absorption by as much as 25%. This problem does not occur with leavened (yeast-raised) bread, as yeast produces enzymes that break down phytate so mineral-binding does not occur.

Minerals can interfere with absorption of each other, too. Iron interferes with zinc absorption, while copper uptake is reduced by the presence of zinc, iron and molybdenum.

CALCIUM

Absorption of calcium usually depends on both the presence of vitamin D and the correct level of acidity to allow calcium salts to break up into their soluble free ions. Low molecular weight calcium salts such as calcium oxalate can be absorbed intact, however, possibly by passing between, rather than through, cells in the intestinal lining. Interestingly, scientists have found that the bioavailability of calcium in brassica vegetables is higher than for dairy products - 61% of calcium found in broccoli is absorbable, compared with only 32% of that in milk. The reason remains unknown.

TEA AND COFFEE

Polyphenols such as tannic acid (found in tea) bind iron and other minerals to reduce their absorption and another unidentified component of coffee inhibits the process. Coffee can reduce iron absorption by up to 80% if drunk within an hour of a meal. It also lowers uptake of zinc and, as it has a diuretic action, is associated with increased losses of magnesium, calcium and other minerals from the body. However, caffeine is an excellent stimulator of gastric acid which can help the absorption of other nutrients.

GRAPEFRUIT JUICE

Grapefruit juice interacts with a number of prescribed and over-the-counter drugs. This interaction was discovered by accident when researchers were looking at the effects of drinking alcohol with a particular blood pressure medicine. Grapefruit juice was used as a mixer and, while the alcohol did not affect the amount of drug circulating in the body, the juice greatly increased blood levels of the medication.This effect can be surprisingly large. For example, taking one particular statin drug (lovastatin) with a glass of grapefruit juice produces the same blood levels of the drug as taking 12 tablets with water. The interaction between grapefruit and food supplements has not been investigated and little information is known, but you may wish to avoid drinking juice with your supplements (especially herbs) just in case.

HOW TO TAKE SUPPLEMENTS

1. Despite the problems mentioned above, vitamin and mineral supplements are usually best taken immediately after food (just four bites or a glass of juice will do). If you have not eaten for more than 20 minutes, don’t take your supplements. Wait until you have a snack/juice and take them then. If taken on an empty stomach, some can make you feel sick or cause indigestion.
2. Wash supplements down with water or orange juice. Don’t take them with coffee or tea, as these may interfere with absorption.
3. Fat-soluble substances (e.g. co-enzyme Q10, evening primrose oil, fish oils and vitamins A, D, E, K) should ideally be taken with food containing some fat (eg. milk). If taking a fish oil supplement that produces fishy ‘burps’, try emulsifying the oil by shaking your dose with a little milk to increase absorption and reduce aftertaste.
4. If taking two or more capsules of the same preparation a day, spread these out over the day, if possible, to maximise absorption and obtain more-even blood levels.
5. If you take a one-a-day vitamin and mineral supplement, it is usually best after your evening meal rather than with breakfast. This is because repair processes and mineral movements in your body are greatest at night when growth hormone is secreted.
6. A day’s dose is better taken at the time you are most likely to remember, however. Don’t feel you have to follow any strict regime if you find difficulty remembering to take supplements at a certain time, or if they do not fit in with your particular lifestyle.
7. It’s easier to remember to take supplements if you get into a routine and take them at the same time each day. Keep them by your toothbrush, for example, or by your keyboard if this helps you remember.
8. If taking capsules, look down at the floor as you swallow to help them go down more easily. For heavier tablets, put your head back as you swallow to help the action of gravity.
9. Don’t swallow supplements in a hurry - if you take your time, your throat muscle will be more relaxed and tablets are less likely to lodge in the gullet.
10. If taking vitamin and mineral supplements makes you feel nauseated, here’s a possible solution: whizz up all the supplements you would normally take during the day in a food blender, or pulverize them in a pestle and mortar. Divide the powder into two to four equal portions. Take each portion (mixed with milk, soup or juice) at regular intervals during the day, part-way through each meal, when your stomach juices are in full flow.

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