Higher fat and lower fiber associated with improved calcium absorption in women.

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Higher fat and lower fiber associated with improved calcium absorption

in women.

 

Anthony Colpo,

November 30, 2004.

 

A few weeks back I told readers about a recently published study that

showed women who ate the most saturated fat had far less narrowing of

their arteries than women who ate the least saturated fat. This was

despite the fact that women eating the most saturated fat were more

likely to smoke!

 

In light of this 'revelation', I figured it would be fitting to

revisit another politically incorrect study indicating important

benefits of dietary fat in women. The study in question, published

four years ago, examined factors that could influence the rate of

calcium absorption in women.

 

As part of the Women's Healthy Lifestyle Project (WHLP), researchers

estimated calcium absorption in 142 healthy pre- and perimenopausal

women. Dietary habits, lifestyle factors, calciotropic hormones, and

vitamin D receptor gene polymorphisms were also assessed.

 

Calcium absorption values averaged 35% among the women and ranged from

17% to 58%. Increased calcium absorption was associated with higher

dietary fat intake, body mass index, serum vitamin D concentrations,

and parathyroid hormone concentrations. Decreased calcium absorption

was associated with total calcium intake, dietary fiber intake,

alcohol consumption, physical activity, and symptoms of constipation.

 

Fat, fiber and bones

 

After adjusting for various confounders, dietary fat, dietary fiber,

serum vitamin D, and alcohol consumption emerged as independent

predictors of calcium absorption.

 

The women were divided into three groups, those in the group with the

lowest ratio of dietary fat to fiber had 19% lower fractional calcium

absorption values than did women with the highest ratio of dietary fat

to fiber(1).

 

It's what you absorb that counts

 

Women are constantly told to ingest more calcium, but are given little

information on the factors that may improve or impair calcium

absorption. This is important, because research shows that calcium

absorption in women can range from 7%-68%(2). Obviously, there's

little to be gained from shoveling calcium down one's gullet if most

of it will simply be excreted…

 

Don't let the results of this study deter you from eating fiber-rich

fruits, nuts, and vegetables--the calcium antagonizing effect of fiber

in this study is most likely explained by cereal fiber. It is

well-known that cereal fiber and legumes contain anti-nutrients such

as phytate, which binds to minerals such as calcium and increases

their excretion from the body.

 

While researchers have observed the fiber in wheat bran to impair

calcium absorption, they have found no detrimental effect from the

fiber in green leafy vegetables such as kale, broccoli, and bok

choy(3-5).

 

As for fats, animal and human studies show that saturated fats improve

mineral absorption, while omega-6-rich polyunsaturated oils decrease

mineral absorption(6-10).

 

Pass the lamb chops, please…

 

References

 

1. Wolf RL, et al. Factors associated with calcium absorption

efficiency in pre- and perimenopausal women. Am. J. Clinical

Nutrition, Aug 2000; 72: 466 - 471.

 

2. Heaney RP, Recker RR. Distribution of calcium absorption in

middle-aged women. American Journal of Clinical Nutrition, 1986; 43:

299-305.

 

3. Weaver CM, et al. Human calcium absorption from whole-wheat

products. J Nutr 1991;121: 1769-75.

 

4. Weaver CM, et al. Wheat bran abolishes the inverse relationship

between calcium load size and absorption fraction in women. J Nutr

1995;126:303-7.

 

5. Heaney RP, et al. Absorbability of calcium from brassica

vegetables: broccoli, bok choy, and kale. J Food Sci 1993;58:1378-80.

 

6. Mahoney AW, et al. Effects of level and source of dietary fat on

the bioavailability of iron from turkey meat for the anemic rat.

Journal of Nutrition, 1980: 110 (8): 1703-1708.

 

7. Johnson PE, et al. The effects of stearic acid and beef tallow on

iron utilization by the rat. Proc Soc Exp Biol Med, 1992; 200 (4):

480-486.

 

8. Koo SI, Ramlet JS. Effect of dietary linoleic acid on the tissue

levels of zinc and copper, and serum high-density lipoprotein

cholesterol. Atherosclerosis, 1984; 50 (2): 123-132.

 

9. Van Dokkum W, et al. Effect of variations in fat and linoleic acid

intake on the calcium, magnesium and iron balance of young men. Ann

Nutr Metab, 1983; 27 (5): 361-369.

 

10. Lukaski HC, et al. Interactions among dietary fat, mineral status,

and performance of endurance athletes: a case study. Int J Sport Nutr

Exerc Metab, Jun 2001; 11 (2): 186-198.