Vitamin survival guide to city life

No matter how healthy our diet and vitamin regime is, our everyday lives and particularly our bad habits sap much of the benefits we assume we've digested. Vitamins may not be able to cure serious disease, as last week's study showed, but they can combat our nutritional deficiencies.

"City life in particular can bring with it specific situations and stresses, some of which we may be aware of and some of which occur internally," points out nutrition consultant Ian Marber, aka the Food Doctor. "Bad habits - and even good ones - can drain your body's store of nutrients and vitamins." Here we list the worst culprits and explain what you can do to remedy their effects.

"A smoker is less efficient at absorbing and retaining nutrients," says Alison Wyndham, founder of The Wyndham Centre, a one-stop-shop for alternative health. "Smoking a single cigarette is thought to knock out 25mg of vitamin C from the body."

What to take

A smoker's requirement for vitamin C increases to about 2,000mg a day. "It is found in citrus fruits and vegetables such as broccoli and spinach, but it would be almost impossible to get this amount from food alone. You will also need to take a vitamin C supplement," says Wyndham. If you're a passive smoker, increase your intake of fruit and vegetables, supplements (vitamins A,C,E and selenium) and green tea.

"Leaches every known vitamin, mineral, essential fat and amino acid from your body," states Patrick Holford of the Institute of Optimum Nutrition. "The more you drink, the more help you need from nutrient-rich foods and supplements."

What to take

Wine, especially red, does have some health benefits (it contains antioxidants), but it also contains sugars that diminish magnesium and potassium levels. Magnesium plays an essential role in many processes, including transmission of nerve impulses and energy production. Potassium aids clear thinking by sending oxygen to the brain. "Alcohol also steals stores of water-soluble vitamins, such as C and folic acid," says Holford. Eating lean poultry and fruit and vegetables along with a standard multi-vitamin containing a full spectrum of B vitamins should cover your needs.

What it depletes

"When stressed, changes occur in the body as adrenaline is released," says Ian Marber. "The effects are a lowered immune system along with certain vitamins being wiped out of the body and used up more rapidly."

What to take

Pop a B-complex supplement, known as "morale" vitamins because of their beneficial effects on the nervous system and mental attitude. Supplement with the "anti-stress" mineral, magnesium. "It's essential for effective nerve functioning and important for converting blood sugar into energy," says Marber.

What it depletes

Regular exercise increases your need for antioxidants - the mainstay being the A,C and E group of vitamins. "You're making more oxidants from burning glucose with oxygen to make energy," explains Holford. "That's why you puff and pant: taking in oxygen and releasing carbon dioxide." Exercise also increases stress at a cellular level, creating minute muscle tears and forming free radicals - unstable molecules that upset normal cell activity.

What to take

Holford recommends a daily antioxidant supplement, not only to fight against free radicals, but to help with the process of converting oxygen into energy. Wyndham also suggests taking essential fatty acids. Found in vegetable, fish and nut oils or taken as a supplement, they're needed to form healthy cells and regulate many functions within the body.

What it depletes

"Coffee acts as an anti-nutrient thirst-quencher and cuts your absorption of iron and other minerals," warns Patrick Holford.

What to take

As well as inhibiting iron, the synergy of the B-complex vitamins are upset within the body, especially inositol. "It metabolises fat and cholesterol," says Wyndham, "and has been found to be important in nourishing brain cells." It is found in brewer's yeast, grapefruit, raisins and cabbage. Drinking large quantities of coffee may increase the risk of osteoporosis. Caffeine robs calcium from the bones. Adding two tablespoons of milk to each cup of coffee will supply enough calcium to counteract this effect. If you take your coffee black, pop a daily calcium supplement.

What it depletes

"Zinc deficiency is most common in women who have been taking the contraceptive pill," says Holford. "The Pill inhibits the absorption of zinc and causes the body to excrete more of it." Zinc is important as it acts as a body policeman: directing and overseeing the efficient flow of body processes.

What to take

Holford advocates that all Pill users take a high-strength multi-vitamin and mineral containing 10mg of zinc. You are also more likely to need increased amounts of B6 and folic acid.

"As well as killing off the bad bacteria, antibiotics can adversely affect the flora inside your gut and kill off beneficial bacteria," points out Marber. "Many people develop yeast and bacterial infections in the lower bowel, mouth or vagina when taking a prescribed course."

What it depletes

"When taking antibiotics, it's always advisable to eat a small pot of live yoghurt to keep gut flora healthy," says Marber, "but this alone is simply not enough. Probiotic supplementation is the key." Probiotics contain strains of Lactobacillus acidophilus and Bifidobacterium lactis that have been shown to survive a slow transit through the acidic contents of the stomach. This means a higher percentage of beneficial organisms are available to colonise the small and large intestines.

What it depletes

"Modern city toxins are a problem for the urban worker," says Marber, "There's greater exposure to traffic fumes containing lead and carbon monoxide which increases the incidence of free radicals and can lead to a whole host of diseases."

What to take

Antioxidant nutrients in the form of vitamins C, E and betacarotene are the antidote to mop up harmful free radicals. Taking a daily supplement containing these three nutrients or eating foods which contain sufficient levels - Marber suggests apples, pears, cashew nuts, citrus fruits and raw vegetables as good sources - are key to helping protect the body.

What it depletes

A survey by mynutrition.co.uk revealed that 76 per cent of people feel tired all the time and 86 per cent feel a definite improvement in energy after changing diet and taking supplementation.

What to take

"Maximising energy is a vital part of city life," says Marber. "The usual guidelines apply: avoid all high-sugar foods and drinks that provide short-term energy. The emphasis is on protein and complex carbohydrates with added vegetables and fruit." For physical energy, consider chromium, magnesium, manganese, copper and iron, all of which can be found in a good-quality multivitamin.

The Wyndham Centre: 020 7404 0023; Ian Marber at The Food Doctor: 020 7792 6700, www.thefooddoctor.com; Patrick Holford at the Institute of Optimum Nutrition: 020 8877 9993.