Nature takes its courses

As our biological clock counts down, it's difficult for even the most fearless junk food eater to ignore how his or her body reacts with time. The process of ageing can demand more than just changing your wardrobe and investing in expensive creams to hide inevitable wrinkles. What you put in your mouth can effect your health.

Ruth Chan, research associate from the department of medicine and therapeutics at Chinese University, suggests that apart from adopting a balanced lifestyle and maintaining high activity levels, regular meal times, eating at home and following a diet low in fat, sugar and salt can also help make for a smoother transition with age. 'Almost 85 per cent of all diseases are caused by lifestyle choices,' she says.

Candy Wong Sze-man, an accredited practising dietitian and executive committee member of the Hong Kong Dietitians Association, adds: 'Only 5 per cent to 10 per cent of cancer cases are inherited; eight out of 10 cancers are closely linked to diet, smoking and lifestyle. A study headed by the World Cancer Research Fund shows that about one-third of cancers can be prevented by maintaining a healthy weight, eating healthily and staying physically active.'

Doris Lau, an accredited dietitian with the United Christian Nethersole Community Health Service, recommends feeding the body with good nutrients and vitamins as early as during adolescence. 'Ageing is a natural process, yet, with good nutrition, ageing can be delayed,' she says.

Different stages in life, however, require specific nutrients as the body changes. Here's what you should be focusing on, depending on your age.

In your 20s
Key nutrients: calcium and vitamin D

With the body's metabolism at its peak, this decade is the best time to eat what you want, when you want - but it's easy to become slightly complacent and forget about the dangers of a poor diet. The importance of eating healthily is often overlooked in the busy transition from carefree adolescence to the rigours of adult life - work, socialising, dating, getting married, or even starting a family. For the busy and stressed, takeaway food becomes an easy and efficient option, though not the most nutritious one.

Carmen Lo, a registered dietitian and Health Post advisory panel member, stresses the importance of a well-balanced diet from early on. 'I have seen children with early diabetes and those in their 20s with heart failure because of their unhealthy and sedentary lifestyle,' she says.

A healthy diet at this stage will ensure minimal problems for the later phases of life, where diseases are more prevalent. Lo says dietary supplements are not necessary; balanced meals, maintaining healthy weight and limiting alcohol consumption are good enough.

In particular, it's an important time to build stronger bones and muscle by consuming more calcium. 'In our 30s, bone loss begins, which can be slowed down if calcium supplies are met,' Lo says. Have more leafy greens and dairy products, such as milk and cheese. According to the International Osteoporosis Foundation, many Hongkongers take only 450mg of calcium daily, far lower than the recommended 1,000mg. The foundation notes that a lack of calcium, coupled with inadequate levels of vitamin D (which helps with calcium absorption), is associated with low bone mass, whereas consuming fruit and vegetables with high calcium has been shown to help with good bone health.

'If sufficient calcium levels are not met, the body pulls nutrients from the bones, which diminishes bone mass more greatly,' says Dr Edith Lau, Asia-Pacific director of the Centre for Clinical and Basic Research. She stresses that calcium alone is not enough to prevent disease. 'The body requires vitamin D and protein combined with weight bearing exercise.'

With men, especially, muscle building hormones such as testosterone are at their highest in their 20s. The foundation states that trying to replenish these lost calcium sources in your 30s will be too late.

It's not difficult to get your fill: just two 240ml glasses of vitamin D-fortified low-fat milk daily will give you 581mg of calcium and five micrograms (mcg) of vitamin D. Then top it up by including tofu, broccoli or salmon in your meals, and snacking on almonds, yogurt or dried figs.

In your 30s
Key nutrients: folate, iron and phytonutrients

Trying to juggle the demands of a career and children can make this decade of life extremely overwhelming.

For those planning to have children, every nutrient is important, but folate is vital during early pregnancy, Chan says. 'Malformations during childbirth can be minimised with enough folate in the diet,' she says. The nutrient supports a healthy pregnancy, prevents neural tube defects and helps the body make new cells. Those who don't want children should still invest in folate-rich foods - high intake of the nutrient may reduce colorectal cancer risk, according to a recent study published in Gastroenterology. To get your 400mcg daily need, try fortified breakfast cereals, baked beans (60 mcg per cup) or asparagus (85mcg per four spears).

The effects of daily stress are probably starting to show up through fine lines on the face and a suppressed immune system. Loading up on antioxidant-rich phytonutrients can help slow the ageing process and ward off heart disease. Chan adds: 'There's a wealth of evidence that shows a diet rich in phytonutrients, can prevent, or at least delay, the onset of cancers and other diseases. Your diet should have a variety of coloured vegetables, since each vegetable and fruit offers a different phytonutrient to fight specific diseases.' Chocolate is another option - recent research published in the Chemistry Central Journal found that the sweet treat is a rich source of antioxidants and contains more polyphenols and flavanols than fruit juice.

Lastly, if you're feeling physically and mentally drained, try topping up your intake of omega-3s - excellent sources include salmon, flax seeds and walnuts. A recent study on healthy young people found that consuming more fish oil, which is rich in omega-3, can reduce both anxiety and inflammation.

In your 40s (and beyond)
Key nutrients: fibre and protein

In this decade, the average person loses 250g of muscle mass and gains 500g of fat each year. Every kilogram of muscle uses about 12 calories a day just to sustain itself, while each kilogram of fat burns only four calories daily, metabolism goes down and weight typically goes up.

'As we age, muscle mass decreases and so does our motivation to exercise. Despite this, we keep eating the same amount of food we consumed [in our younger years],' says Bernice Cheung Ho-ki, registered dietitian of the Centre for Nutritional Studies at the Chinese University's faculty of medicine. The best way to beat this trend, says Cheung, is to start healthy habits from a young age. But if you didn't, there's still hope.

Fill up on protein, fruit and vegetables; and fibre can help, according to Leslie Bonci, a registered dietitian and author of the new book The Active Calorie Diet. She writes that protein (one quarter of your plate) can boost post-meal calorie burn by 25 to 30 per cent; fruit and vegetables (one half of your plate) by 20 per cent; and fibre (one quarter of your plate) by 10 per cent. Protein also helps in building muscle, while fibre makes you feel fuller for longer and also helps decrease cholesterol and risk of heart disease.

Try eating 'energising' foods. According to Bonci, green tea contains caffeine (a known metabolism booster) and catechins, an antioxidant that raises resting metabolism by 4 per cent. Dark chocolate contains both substances, but stick to a small serving each day to limit your fat and calories.

Remember to keep getting your daily need of calcium and vitamin D, especially women. With the onset of menopause and declining oestrogen levels, the body absorbs less calcium from the diet and loses more bone mass, which could lead to osteoporosis-related fractures.

Overall, the World Cancer Research Fund suggests a lower intake of salty, fatty and sugary foods to stay healthy well into your 50s. Says Chan: 'The most important thing is to adopt a healthy lifestyle and not get obese, since this is an underpinning factor to all diseases.'