Читать книгу Eating for Sport - Shelly Meltzer - Страница 36

Recommendations for nutrition in ageing athletes should focus on both the nutritional requirements of the ageing process and the nutrient needs for exercising.

An older athlete has a lower daily energy requirement due to decreases in muscle mass, aerobic capacity and the decreased capacity to store muscle glycogen (due to reduced muscle mass). For protein, carbohydrate and fat, requirements are given as ranges because the specific amount will vary depending on the individual’s health status and goals. For example, older athletes with raised blood cholesterol levels may need to keep their fat intake to the lower end of the range, whereas someone needing to lose weight may respond to a higher protein diet.

There is an increased need for calcium and vitamin D to reduce the rate at which bone density is lost. Vitamins B₆ and E and zinc are important for immune function. The recommendations given for the B vitamins folate, pyridoxine and B₁₂ are based on their ability to lower homocysteine levels, a known risk factor for the development of coronary heart disease. Note, however, that there are upper limits of safety and that excessive dosages are unsafe. Zinc and iron intakes are often low in older people, especially if they are vegetarian. Master athletes should therefore always aim to achieve the RDAs/DRVs for these nutrients (see pp82, 89). Calcium requirements for men and women increase from 1000 to 1200mg/day over the age of 51 years with an upper limit of safety of 2500mg/day. DRVs in the United Kingdom differ (see p10). Dietary sources of vitamin C will enhance the absorption of all of these minerals.

NUTRIENT	DAILY REQUIREMENT
MACRONUTRIENTS
Energy	Basal requirements decrease, although extra is needed to cover training
Protein	1.2–1.7g per kg body weight
Carbohydrate	50–60%
Fat	20–30%
MICRONUTRIENTS
Vitamin B6	2mg
Vitamin B12	3.6µg
Folate	400µg
Vitamin D	51–70 years: 10µg; >70years >15µg/day
Calcium	1200mg (>65 years)

Some suggested intakes for master athletes, taking physical activity into account.

Vitamin C-rich foods, like citrus, enhance the absorption of iron, calcium and zinc.